Heterozygous loss-of-function variants in DOCK4 cause neurodevelopmental delay and microcephaly

Neurons form the basic anatomical and functional structure of the nervous system, and defects in neuronal differentiation or formation of neurites are associated with various psychiatric and neurodevelopmental disorders. Dynamic changes in the cytoskeleton are essential for this process, which is, inter alia, controlled by the dedicator of cytokinesis 4 (DOCK4) through the activation of RAC1. Here, we clinically describe 7 individuals (6 males and one female) with variants in DOCK4 and overlapping phenotype of mild to severe global developmental delay. Additional symptoms include coordination or gait abnormalities, microcephaly, nonspecific brain malformations, hypotonia and seizures. Four individuals carry missense variants (three of them detected de novo) and three individuals carry null variants (two of them maternally inherited). Molecular modeling of the heterozygous missense variants suggests that the majority of them affect the globular structure of DOCK4. In vitro functional expression studies in transfected Neuro-2A cells showed that all missense variants impaired neurite outgrowth. Furthermore, Dock4 knockout Neuro-2A cells also exhibited defects in promoting neurite outgrowth. Our results, including clinical, molecular and functional data, suggest that loss-of-function variants in DOCK4 probable cause a variable spectrum of a novel neurodevelopmental disorder with microcephaly.

Biallelic ATP2B1 variants as a likely cause of a novel neurodevelopmental malformation syndrome with primary hypoparathyroidism

ATP2B1 encodes plasma membrane calcium-transporting-ATPase1 and plays an essential role in maintaining intracellular calcium homeostasis that regulates diverse signaling pathways. Heterozygous de novo missense and truncating ATP2B1 variants are associated with a neurodevelopmental phenotype of variable expressivity. We describe a proband with distinctive craniofacial gestalt, Pierre-Robin sequence, neurodevelopmental and growth deficit, periventricular heterotopia, brachymesophalangy, cutaneous syndactyly, and persistent hypocalcemia from primary hypoparathyroidism. Proband-parent trio exome sequencing identified compound heterozygous ATP2B1 variants: a maternally inherited splice-site (c.3060+2 T > G) and paternally inherited missense c.2938 G > T; p.(Val980Leu). Reverse-transcription-PCR on the proband's fibroblast-derived mRNA showed aberrantly spliced ATP2B1 transcripts targeted for nonsense-mediated decay. All correctly-spliced ATP2B1 mRNA encoding p.(Val980Leu) functionally causes decreased cellular Ca2+ extrusion. Immunoblotting showed reduced fibroblast ATP2B1. We conclude that biallelic ATP2B1 variants are the likely cause of the proband's phenotype, strengthening the association of ATP2B1 as a neurodevelopmental gene and expanding the phenotypic characterization of a biallelic loss-of-function genotype.

CUX1-related neurodevelopmental disorder: deep insights into phenotype-genotype spectrum and underlying pathology

Heterozygous, pathogenic CUX1 variants are associated with global developmental delay or intellectual disability. This study delineates the clinical presentation in an extended cohort and investigates the molecular mechanism underlying the disorder in a Cux1+/- mouse model. Through international collaboration, we assembled the phenotypic and molecular information for 34 individuals (23 unpublished individuals). We analyze brain CUX1 expression and susceptibility to epilepsy in Cux1+/- mice. We describe 34 individuals, from which 30 were unrelated, with 26 different null and four missense variants. The leading symptoms were mild to moderate delayed speech and motor development and borderline to moderate intellectual disability. Additional symptoms were muscular hypotonia, seizures, joint laxity, and abnormalities of the forehead. In Cux1+/- mice, we found delayed growth, histologically normal brains, and increased susceptibility to seizures. In Cux1+/- brains, the expression of Cux1 transcripts was half of WT animals. Expression of CUX1 proteins was reduced, although in early postnatal animals significantly more than in adults. In summary, disease-causing CUX1 variants result in a non-syndromic phenotype of developmental delay and intellectual disability. In some individuals, this phenotype ameliorates with age, resulting in a clinical catch-up and normal IQ in adulthood. The post-transcriptional balance of CUX1 expression in the heterozygous brain at late developmental stages appears important for this favorable clinical course.

De Novo Variants in RAB11B Cause Various Degrees of Global Developmental Delay and Intellectual Disability in Children

BACKGROUND

RAB11B was described previously once with a severe form of intellectual disability. We aim at validation and delineation of the role of RAB11B in neurodevelopmental disorders.

METHODS

We present seven novel individuals with disease-associated variants in RAB11B when compared with the six cases described in the literature. We performed a cross-sectional analysis to identify the clinical spectrum and the core phenotype. Additionally, structural effects of the variants were assessed by molecular modeling.

RESULTS

Seven distinct de novo missense variants were identified, three of them recurrent (p.(Gly21Arg), p.(Val22Met), and p.(Ala68Thr)). Molecular modeling suggests that those variants either affect the nucleotide binding (at amino acid positions 21, 22, 33, 68) or the interaction with effector molecules (at positions 72 and 75). Our data confirmed the main manifestations as neurodevelopmental disorder with intellectual disability (85%), muscular hypotonia (83%), structural brain anomalies (77%), and visual impairment (70%). Combined analysis indicates a genotype-phenotype correlation; variants impacting the nucleotide binding cause a severe phenotype with intellectual disability, and variants outside the binding pocket lead to a milder phenotype with epilepsy.

CONCLUSIONS

We confirm that disease-associated missense variants in RAB11B cause a neurodevelopmental disorder and suggest a genotype-phenotype correlation based on the impact on nucleotide binding functionality of RAB11B.

POU3F3-related disorder: Defining the phenotype and expanding the molecular spectrum

POU3F3 variants cause developmental delay, behavioral problems, hypotonia and dysmorphic features. We investigated the phenotypic and genetic landscape, and genotype-phenotype correlations in individuals with POU3F3-related disorders. We recruited unpublished individuals with POU3F3 variants through international collaborations and obtained updated clinical data on previously published individuals. Trio exome sequencing or single exome sequencing followed by segregation analysis were performed in the novel cohort. Functional effects of missense variants were investigated with 3D protein modeling. We included 28 individuals (5 previously published) from 26 families carrying POU3F3 variants; 23 de novo and one inherited from an affected parent. Median age at study inclusion was 7.4 years. All had developmental delay mainly affecting speech, behavioral difficulties, psychiatric comorbidities and dysmorphisms. Additional features included gastrointestinal comorbidities, hearing loss, ophthalmological anomalies, epilepsy, sleep disturbances and joint hypermobility. Autism, hearing and eye comorbidities, dysmorphisms were more common in individuals with truncating variants, whereas epilepsy was only associated with missense variants. In silico structural modeling predicted that all (likely) pathogenic variants destabilize the DNA-binding region of POU3F3. Our study refined the phenotypic and genetic landscape of POU3F3-related disorders, it reports the functional properties of the identified pathogenic variants, and delineates some genotype-phenotype correlations.

The clinical and genetic spectrum of autosomal-recessive TOR1A-related disorders

In the field of rare diseases, progress in molecular diagnostics led to the recognition that variants linked to autosomal-dominant neurodegenerative diseases of later onset can, in the context of biallelic inheritance, cause devastating neurodevelopmental disorders and infantile or childhood-onset neurodegeneration. TOR1A-associated arthrogryposis multiplex congenita 5 (AMC5) is a rare neurodevelopmental disorder arising from biallelic variants in TOR1A, a gene that in the heterozygous state is associated with torsion dystonia-1 (DYT1 or DYT-TOR1A), an early-onset dystonia with reduced penetrance. While 15 individuals with AMC5-TOR1A have been reported (less than 10 in detail), a systematic investigation of the full disease-associated spectrum has not been conducted. Here, we assess the clinical, radiological and molecular characteristics of 57 individuals from 40 families with biallelic variants in TOR1A. Median age at last follow-up was 3 years (0-24 years). Most individuals presented with severe congenital flexion contractures (95%) and variable developmental delay (79%). Motor symptoms were reported in 79% and included lower limb spasticity and pyramidal signs, as well as gait disturbances. Facial dysmorphism was an integral part of the phenotype, with key features being a broad/full nasal tip, narrowing of the forehead and full cheeks. Analysis of disease-associated manifestations delineated a phenotypic spectrum ranging from normal cognition and mild gait disturbance to congenital arthrogryposis, global developmental delay, intellectual disability, absent speech and inability to walk. In a subset, the presentation was consistent with foetal akinesia deformation sequence with severe intrauterine abnormalities. Survival was 71%, with higher mortality in males. Death occurred at a median age of 1.2 months (1 week-9 years), due to respiratory failure, cardiac arrest or sepsis. Analysis of brain MRI studies identified non-specific neuroimaging features, including a hypoplastic corpus callosum (72%), foci of signal abnormality in the subcortical and periventricular white matter (55%), diffuse white matter volume loss (45%), mega cisterna magna (36%) and arachnoid cysts (27%). The molecular spectrum included 22 distinct variants, defining a mutational hotspot in the C-terminal domain of the Torsin-1A protein. Genotype-phenotype analysis revealed an association of missense variants in the 3-helix bundle domain to an attenuated phenotype, while missense variants near the Walker A/B motif as well as biallelic truncating variants were linked to early death. In summary, this systematic cross-sectional analysis of a large cohort of individuals with biallelic TOR1A variants across a wide age-range delineates the clinical and genetic spectrum of TOR1A-related autosomal-recessive disease and highlights potential predictors for disease severity and survival.

Broadening the phenotypic and molecular spectrum of FINCA syndrome: Biallelic NHLRC2 variants in 15 novel individuals

FINCA syndrome [MIM: 618278] is an autosomal recessive multisystem disorder characterized by fibrosis, neurodegeneration and cerebral angiomatosis. To date, 13 patients from nine families with biallelic NHLRC2 variants have been published. In all of them, the recurrent missense variant p.(Asp148Tyr) was detected on at least one allele. Common manifestations included lung or muscle fibrosis, respiratory distress, developmental delay, neuromuscular symptoms and seizures often followed by early death due to rapid disease progression.Here, we present 15 individuals from 12 families with an overlapping phenotype associated with nine novel NHLRC2 variants identified by exome analysis. All patients described here presented with moderate to severe global developmental delay and variable disease progression. Seizures, truncal hypotonia and movement disorders were frequently observed. Notably, we also present the first eight cases in which the recurrent p.(Asp148Tyr) variant was not detected in either homozygous or compound heterozygous state.We cloned and expressed all novel and most previously published non-truncating variants in HEK293-cells. From the results of these functional studies, we propose a potential genotype-phenotype correlation, with a greater reduction in protein expression being associated with a more severe phenotype.Taken together, our findings broaden the known phenotypic and molecular spectrum and emphasize that NHLRC2-related disease should be considered in patients presenting with intellectual disability, movement disorders, neuroregression and epilepsy with or without pulmonary involvement.

De novo variants in CNOT9 cause a neurodevelopmental disorder with or without epilepsy

PURPOSE

The study aimed to clinically and molecularly characterize the neurodevelopmental disorder associated with heterozygous de novo variants in CNOT9.

METHODS

Individuals were clinically examined. Variants were identified using exome or genome sequencing. These variants were evaluated using in silico predictions and their functional relevance was further assessed by molecular models and research in the literature. The variants have been classified according to the criteria of the American College of Medical Genetics (ACMG).

RESULTS

We report on seven individuals carrying de novo missense variants in CNOT9; p.(Arg46Gly), p.(Pro131Leu), p.(Arg227His) and, recurrent in four unrelated individuals, p.(Arg292Trp). All affected persons have DD/ID, with five of them showing seizures. Other symptoms include muscular hypotonia, facial dysmorphism, and behavioral abnormalities. Molecular modeling predicted that the variants are damaging and would lead to reduced protein stability or impaired recognition of interaction partners. Functional analyses in previous studies showed a pathogenic effect of p.(Pro131Leu) and p.(Arg227His).

CONCLUSION

We propose CNOT9 as a novel gene for neurodevelopmental disorder and epilepsy.

De novo variants in ATP2B1 lead to neurodevelopmental delay

Calcium (Ca²⁺) is a universal second messenger involved in synaptogenesis and cell survival; consequently, its regulation is important for neurons. ATPase plasma membrane Ca²⁺ transporting 1 (ATP2B1) belongs to the family of ATP-driven calmodulin-dependent Ca²⁺ pumps that participate in the regulation of intracellular free Ca²⁺. Here, we clinically describe a cohort of 12 unrelated individuals with variants in ATP2B1 and an overlapping phenotype of mild to moderate global development delay. Additional common symptoms include autism, seizures, and distal limb abnormalities. Nine probands harbor missense variants, seven of which were in specific functional domains, and three individuals have nonsense variants. 3D structural protein modeling suggested that the variants have a destabilizing effect on the protein. We performed Ca²⁺ imaging after introducing all nine missense variants in transfected HEK293 cells and showed that all variants lead to a significant decrease in Ca²⁺ export capacity compared with the wild-type construct, thus proving their pathogenicity. Furthermore, we observed for the same variant set an incorrect intracellular localization of ATP2B1. The genetic findings and the overlapping phenotype of the probands as well as the functional analyses imply that de novo variants in ATP2B1 lead to a monogenic form of neurodevelopmental disorder.

The Relation of Surgical Procedures and Diagnosis Groups to Unplanned Readmission in Spinal Neurosurgery: A Retrospective Single Center Study

Background: Unplanned readmission has gained increasing interest as a quality marker for inpatient care, as it is associated with patient mortality and higher economic costs. Spinal neurosurgery is characterized by a lack of epidemiologic readmission data. The aim of this study was to identify causes and predictors for unplanned readmissions related to index diagnoses and surgical procedures. Methods: In this study, from 2015 to 2017, spinal neurosurgical procedures were recorded for surgical and non-surgical treated patients. The main reasons for an unplanned readmission within 30 days following discharge were identified. Multivariate logarithmic regression revealed predictors of unplanned readmission. Results: A total of 1172 patient records were examined, of which 4.27% disclosed unplanned readmissions. Among the surgical patients, the readmission rate was 4.06%, mainly attributable to surgical site infections, while it was 5.06% for the non-surgical patients, attributable to uncontrolled pain. A night-time surgery presented as the independent predictive factor. Conclusion: In the heterogeneous group of spinal neurosurgical patients, stratification into diagnostic groups is necessary for statistical analysis. Degenerative lumbar spinal stenosis and spinal abscesses are mainly affected by unplanned readmission. The surgical procedure dorsal root ganglion stimulation is an independent predictor of unplanned re-hospitalizations, as is the timing of surgery.

The clinical and molecular spectrum of QRICH1 associated neurodevelopmental disorder

De novo variants in QRICH1 (Glutamine-rich protein 1) has recently been reported in 11 individuals with intellectual disability (ID). The function of QRICH1 is largely unknown but it is likely to play a key role in the unfolded response of endoplasmic reticulum stress through transcriptional control of proteostasis. In this study, we present 27 additional individuals and delineate the clinical and molecular spectrum of the individuals (n = 38) with QRICH1 variants. The main clinical features were mild to moderate developmental delay/ID (71%), nonspecific facial dysmorphism (92%) and hypotonia (39%). Additional findings included poor weight gain (29%), short stature (29%), autism spectrum disorder (29%), seizures (24%) and scoliosis (18%). Minor structural brain abnormalities were reported in 52% of the individuals with brain imaging. Truncating or splice variants were found in 28 individuals and 10 had missense variants. Four variants were inherited from mildly affected parents. This study confirms that heterozygous QRICH1 variants cause a neurodevelopmental disorder including short stature and expands the phenotypic spectrum to include poor weight gain, scoliosis, hypotonia, minor structural brain anomalies, and seizures. Inherited variants from mildly affected parents are reported for the first time, suggesting variable expressivity.

Exome first approach to reduce diagnostic costs and time - retrospective analysis of 111 individuals with rare neurodevelopmental disorders

This single-center study aims to determine the time, diagnostic procedure, and cost saving potential of early exome sequencing in a cohort of 111 individuals with genetically confirmed neurodevelopmental disorders. We retrospectively collected data regarding diagnostic time points and procedures from the individuals' medical histories and developed criteria for classifying diagnostic procedures in terms of requirement, followed by a cost allocation. All genetic variants were re-evaluated according to ACMG recommendations and considering the individuals' phenotype. Individuals who developed first symptoms of their underlying genetic disorder when Next Generation Sequencing (NGS) diagnostics were already available received a diagnosis significantly faster than individuals with first symptoms before this cutoff. The largest amount of potentially dispensable diagnostics was found in genetic, metabolic, and cranial magnetic resonance imaging examinations. Out of 407 performed genetic examinations, 296 (72.7%) were classified as potentially dispensable. The same applied to 36 (27.9%) of 129 cranial magnetic resonance imaging and 111 (31.8%) of 349 metabolic examinations. Dispensable genetic examinations accounted 302,947.07€ (90.2%) of the total 335,837.49€ in potentially savable costs in this cohort. The remaining 32,890.42€ (9.8%) are related to non-required metabolic and cranial magnetic resonance imaging diagnostics. On average, the total potentially savable costs in our study amount to €3,025.56 per individual. Cost savings by first tier exome sequencing lie primarily in genetic, metabolic, and cMRI testing in this German cohort, underscoring the utility of performing exome sequencing at the beginning of the diagnostic pathway and the potential for saving diagnostic costs and time.

Causes and Predictors of Unplanned Readmission in Cranial Neurosurgery

OBJECTIVE

A better understanding of the risks and reasons for unplanned readmission is an essential component in reducing costs in the health care system and in optimizing patient safety and satisfaction. The reasons for unplanned readmission vary between different disciplines and procedures. The aim of this study was to identify reasons for readmission in view of different diagnoses in cranial neurosurgery.

METHODS

In this single-center retrospective study, adult patients after neurosurgical treatment were analyzed and grouped according to the indication based on International Classification of Diseases and Related Health Problems, Tenth Revision, German Modification diagnosis codes. The main outcome measure was unplanned readmission within 30 days of discharge. Further logistic regression models were performed to identify factors associated with unplanned rehospitalization.

RESULTS

Of the 2474 patients analyzed, 183 underwent unplanned rehospitalization. Readmission rates differed between the diagnosis groups, with 9.19% in neoplasm, 8.26% in hydrocephalus, 5.76% in vascular, 6.13% after trauma, and 8.05% in the functional group. Several causes were considered to be preventable, such as wound healing disorders, seizures, or social reasons. Younger age, length of first stay, surgical treatment, and side diagnoses were predictors for unplanned readmission. Diagnoses with an increased risk of readmission were glioblastoma, traumatic subdural hematoma, or chronic subdural hematoma.

CONCLUSIONS

Reasons and predictors for an unplanned readmission differ considerably among the index diagnosis groups. In addition to well-known reasons for readmission, we identified social indication, meaning a lack of home care, which is particularly prevalent in oncologic and elderly patients. A transitional care program could benefit these vulnerable patients.

Non-enzymatic reaction of carnosine and glyceraldehyde-3-phosphate accompanies metabolic changes of the pentose phosphate pathway

OBJECTIVES

Carnosine (β-alanyl-l-histidine) is a naturally occurring dipeptide that selectively inhibits cancer cell growth, possibly by influencing glucose metabolism. As its precise mode of action and its primary targets are unknown, we analysed carnosine's effect on metabolites and pathways in glioblastoma cells.

MATERIALS AND METHODS

Glioblastoma cells, U87, T98G and LN229, were treated with carnosine, and metabolites were analysed by gas chromatography coupled with mass spectrometry. Furthermore, mitochondrial ATP production was determined by extracellular flux analysis and reaction products of carnosine were investigated using mass spectrometry.

RESULTS

Carnosine decreased the intracellular abundance of several metabolites indicating a reduced activity of the pentose phosphate pathway, the malate-aspartate shuttle and the glycerol phosphate shuttle. Mitochondrial respiration was reduced in U87 and T98G but not in LN229 cells, independent of whether glucose or pyruvate was used as substrate. Finally, we demonstrate non-enzymatic reaction of carnosine with dihydroxyacetone phosphate and glyceraldehyde-3-phosphate. However, glycolytic flux from glucose to l-lactate appeared not to be affected by the reaction of carnosine with the metabolites.

CONCLUSIONS

Carnosine reacts non-enzymatically with glycolytic intermediates reducing the activity of the pentose phosphate pathway which is required for cell proliferation. Although the activity of the malate-aspartate and the glycerol phosphate shuttle appear to be affected, reduced mitochondrial ATP production under the influence of the dipeptide is cell-specific and appears to be independent of the effect on the shuttles.

Carnosine increases efficiency of temozolomide and irradiation treatment of isocitrate dehydrogenase-wildtype glioblastoma cells in culture

Aim: The naturally occurring dipeptide carnosine (CAR) has been considered for glioblastoma therapy. As CAR also protects against ionizing irradiation (IR), we investigated whether it may counteract standard therapy consisting of postsurgery IR and treatment with temozolomide (TMZ). Materials & methods: Four isocitrate dehydrogenase-wildtype primary cell cultures were exposed to different doses of IR and different concentrations of TMZ and CAR. After exposure, viability under the different conditions and combinations of them was determined. Results: All cultures responded to treatment with TMZ and IR with reduced viability. CAR further decreased viability when TMZ and IR were combined. Conclusion: Treatment with CAR does not counteract glioblastoma standard therapy. As the dipeptide also protects nontumor cells from IR, it may reduce deleterious side effects of treatment.

The Chk1 inhibitor SAR-020106 sensitizes human glioblastoma cells to irradiation, to temozolomide, and to decitabine treatment

Background

Glioblastoma is the most common and aggressive brain tumour in adults with a median overall survival of only 14 months after standard therapy with radiation therapy (IR) and temozolomide (TMZ). In a novel multimodal treatment approach we combined the checkpoint kinase 1 (Chk1) inhibitor SAR-020106 (SAR), disrupting homologue recombination, with standard DNA damage inducers (IR, TMZ) and the epigenetic/cytotoxic drug decitabine (5-aza-2′-deoxycitidine, 5-aza-dC). Different in vitro glioblastoma models are monitored to evaluate if the impaired DNA damage repair may chemo/radiosensitize the tumour cells.

Methods

Human p53-mutated (p53-mut) and -wildtype (p53-wt) glioblastoma cell lines (p53-mut: LN405, T98G; p53-wt: A172, DBTRG) and primary glioblastoma cells (p53-mut: P0297; p53-wt: P0306) were treated with SAR combined with TMZ, 5-aza-dC, and/or IR and analysed for induction of apoptosis (AnnexinV and sub-G1 assay), cell cycle distribution (nuclear PI staining), DNA damage (alkaline comet or gH2A.X assay), proliferation inhibition (BrdU assay), reproductive survival (clonogenic assay), and potential tumour stem cells (nestin^pos/GFAP^neg fluorescence staining). Potential treatment-induced neurotoxicity was evaluated on nestin-positive neural progenitor cells in a murine entorhinal-hippocampal slice culture model.

Results

SAR showed radiosensitizing effects on the induction of apoptosis and on the reduction of long-term survival in p53-mut and p53-wt glioblastoma cell lines and primary cells. In p53-mut cells, this effect was accompanied by an abrogation of the IR-induced G2/M arrest and an enhancement of IR-induced DNA damage by SAR treatment. Also TMZ and 5-aza-dC acted radioadditively albeit to a lesser extent. The multimodal treatment achieved the most effective reduction of clonogenicity in all tested cell lines and did not affect the ratio of nestin^pos/GFAP^neg cells. No neurotoxic effects were detected when the number of nestin-positive neural progenitor cells remained unchanged after multimodal treatment.

Conclusion

The Chk1 inhibitor SAR-020106 is a potent sensitizer for DNA damage-induced cell death in glioblastoma therapy strongly reducing clonogenicity of tumour cells. Selectively enhanced p53-mut cell death may provide stronger responses in tumours defective of non-homologous end joining (NHEJ). Our results suggest that a multimodal therapy involving DNA damage inducers and DNA repair inhibitors might be an effective anti-tumour strategy with a low risk of neurotoxicity.

Carnosine inhibits glioblastoma growth independent from PI3K/Akt/mTOR signaling

Glioblastoma is a high-grade glioma with poor prognosis even after surgery and standard therapy. Here, we asked whether carnosine (β-alanyl-L-histidine), a naturally occurring dipeptide, exert its anti-neoplastic effect on glioblastoma cells via PI3K/Akt/mTOR signaling. Therefore, glioblastoma cells from the lines U87 and T98G were exposed to carnosine, to the mTOR inhibitor rapamycin and to the PI3K inhibitor Ly-294,002. Pyruvate dehydrogenase kinase (PDK4) expression, known to be a target of PI3K/Akt/mTOR, and which is also affected by carnosine, was analyzed by RT-qPCR, and reporter gene assays with the human PDK4 promoter were performed. Cell viability was assessed by cell-based assays and mTOR and Akt phosphorylation by Western blotting. Rapamycin and Ly-294,002 increased PDK4 mRNA expression in both cell lines but significance was only reached in U87. Carnosine significantly increased expression in both lines. A significant combinatorial effect of carnosine was only detected in U87 when the dipeptide was combined with Ly-294,002. Reporter gene assays revealed no specific effect of carnosine on the human PDK4 promoter, whereas both inhibitors increased reporter gene expression. Rapamycin reduced phosphorylation of mTOR, and Ly-294,002 that of Akt. A significant reduction of Akt phosphorylation was observed in the presence of carnosine in U87 but not in T98G, and carnosine had no effect on mTOR phosphorylation. Cell viability as determined by ATP in cell lysates was reduced only in the presence of carnosine. We conclude that carnosine’s anti-neoplastic effect is independent from PI3K/Akt/mTOR signaling. As the dipeptide reduced viability in tumor cells that do not respond to PI3K or mTOR inhibitors, it appears to be worth to further investigate the mechanisms by which carnosine exerts its anti-tumor effect and to consider it for therapy, especially as it is a naturally occurring compound that has already been used for the treatment of other diseases without indication of side-effects.

The proton-coupled oligopeptide transporters PEPT2, PHT1 and PHT2 mediate the uptake of carnosine in glioblastoma cells

The previous studies demonstrated that carnosine (β-alanyl-L-histidine) inhibits the growth of tumor cells in vitro and in vivo. Considering carnosine for the treatment of glioblastoma, we investigated which proton-coupled oligopeptide transporters (POTs) are present in glioblastoma cells and how they contribute to the uptake of carnosine. Therefore, mRNA expression of the four known POTs (PEPT1, PEPT2, PHT1, and PHT2) was examined in three glioblastoma cell lines, ten primary tumor cell cultures, in freshly isolated tumor tissue and in healthy brain. Using high-performance liquid chromatography coupled to mass spectrometry, the uptake of carnosine was investigated in the presence of competitive inhibitors and after siRNA-mediated knockdown of POTs. Whereas PEPT1 mRNA was not detected in any sample, expression of the three other transporters was significantly increased in tumor tissue compared to healthy brain. In cell culture, PHT1 expression was comparable to expression in tumor tissue, PHT2 exhibited a slightly reduced expression, and PEPT2 expression was reduced to normal brain tissue levels. In the cell line LN405, the competitive inhibitors β-alanyl-L-alanine (inhibits all transporters) and L-histidine (inhibitor of PHT1/2) both inhibited the uptake of carnosine. SiRNA-mediated knockdown of PHT1 and PHT2 revealed a significantly reduced uptake of carnosine. Interestingly, despite its low expression at the level of mRNA, knockdown of PEPT2 also resulted in decreased uptake. In conclusion, our results demonstrate that the transporters PEPT2, PHT1, and PHT2 are responsible for the uptake of carnosine into glioblastoma cells and full function of all three transporters is required for maximum uptake.

Assessment of ApoC1, LuzP6, C12orf75 and OCC-1 in cystic glioblastoma using MALDI-TOF mass spectrometry, immunohistochemistry and qRT-PCR

Mass spectrometric analysis of glioblastoma cyst fluids has disclosed a protein peak with m/z 6424–6433. Among the proteins, potentially generating this peak are ApoC1 and LuzP6. To further elucidate protein expression of glioblastoma cells, we analyzed MALDI–TOF results of cyst fluid, performed immunohistochemistry and mRNA analysis. MALDI–TOF protein extraction from 24 glioblastoma cyst fluids was performed with a weak cation exchange. 50 glioblastoma samples were stained with two custom-made antibodies against LuzP6 and commercial antibodies against ApoC1, C12orf75 and OCC-1 and analyzed. For mRNA detection, 16 tissue samples were stored in RNAlater, extracted using the miRNeasy kit and reversely transcribed. For 12 patients, synopsis of results from all three examinations was possible. MALDI–TOF confirmed the peak at 6433 Da in 75% of samples. Immunohistochemically, LuzP6 was detected in 92% (LuzP6_1–29) and 96% (LuzP6_30–58) of samples and ApoC1 in 66%. Mean mRNA levels were highest for ApoC1, followed by LuzP6. No correlation between mRNA expression, immunohistochemical staining and intensity of the MALDI–TOF peaks was found. An unequivocal identification of one protein as the source for the 6433 peak is not possible, but our results point to ApoC1 and LuzP6 as the underlying proteins.

Carnosine selectively inhibits migration of IDH-wildtype glioblastoma cells in a co-culture model with fibroblasts

Background

Glioblastoma (GBM) is a tumor of the central nervous system. After surgical removal and standard therapy, recurrence of tumors is observed within 6–9 months because of the high migratory behavior and the infiltrative growth of cells. Here, we investigated whether carnosine (β-alanine-l-histidine), which has an inhibitory effect on glioblastoma proliferation, may on the opposite promote invasion as proposed by the so-called “go-or-grow concept”.

Methods

Cell viability of nine patient derived primary (isocitrate dehydrogenase wildtype; IDH1R132H non mutant) glioblastoma cell cultures and of eleven patient derived fibroblast cultures was determined by measuring ATP in cell lysates and dehydrogenase activity after incubation with 0, 50 or 75 mM carnosine for 48 h. Using the glioblastoma cell line T98G, patient derived glioblastoma cells and fibroblasts, a co-culture model was developed using 12 well plates and cloning rings, placing glioblastoma cells inside and fibroblasts outside the ring. After cultivation in the presence of carnosine, the number of colonies and the size of the tumor cell occupied area were determined.

Results

In 48 h single cultures of fibroblasts and tumor cells, 50 and 75 mM carnosine reduced ATP in cell lysates and dehydrogenase activity when compared to the corresponding untreated control cells. Co-culture experiments revealed that after 4 week exposure to carnosine the number of T98G tumor cell colonies within the fibroblast layer and the area occupied by tumor cells was reduced with increasing concentrations of carnosine. Although primary cultured tumor cells did not form colonies in the absence of carnosine, they were eliminated from the co-culture by cell death and did not build colonies under the influence of carnosine, whereas fibroblasts survived and were healthy.

Conclusions

Our results demonstrate that the anti-proliferative effect of carnosine is not accompanied by an induction of cell migration. Instead, the dipeptide is able to prevent colony formation and selectively eliminates tumor cells in a co-culture with fibroblasts.

Electronic supplementary material

The online version of this article (10.1186/s12935-018-0611-2) contains supplementary material, which is available to authorized users.

Pyruvate attenuates the anti-neoplastic effect of carnosine independently from oxidative phosphorylation

Here we analyzed whether the anti-neoplastic effect of carnosine, which inhibits glycolytic ATP production, can be antagonized by ATP production via oxidative phosphorylation fueled by pyruvate. Therefore, glioblastoma cells were cultivated in medium supplemented with glucose, galactose or pyruvate and in the presence or absence of carnosine. CPI-613 was employed to inhibit the entry of pyruvate into the tricarboxylic acid cycle and 2,4-dinitrophenol to inhibit oxidative phosphorylation. Energy metabolism and viability were assessed by cell based assays and histochemistry.ATP in cell lysates and dehydrogenase activity in living cells revealed a strong reduction of viability under the influence of carnosine when cells received glucose or galactose but not in the presence of pyruvate. CPI-613 and 2,4-dinitrophenol reduced viability of cells cultivated in pyruvate, but no effect was seen in the presence of glucose. No effect of carnosine on viability was observed in the presence of glucose and pyruvate even in the presence of 2,4-dinitrophenol or CPI-613.In conclusion, glioblastoma cells produce ATP from pyruvate via the tricarboxylic acid cycle and oxidative phosphorylation in the absence of a glycolytic substrate. In addition, pyruvate attenuates the anti-neoplastic effect of carnosine, even when ATP production via tricarboxylic acid cycle and oxidative phosphorylation is blocked. We also observed an inhibitory effect of carnosine on the tricarboxylic acid cycle and a stimulating effect of 2,4-dinitrophenol on glycolytic ATP production.

Metabolic response of glioblastoma cells associated with glucose withdrawal and pyruvate substitution as revealed by GC-MS

BACKGROUND

Tumor cells are highly dependent on glucose even in the presence of oxygen. This concept called the Warburg effect is a hallmark of cancer and strategies are considered to therapeutically exploit the phenomenon such as ketogenic diets. The success of such strategies is dependent on a profound understanding of tumor cell metabolism. With new techniques it is now possible to thoroughly analyze the metabolic responses to the withdrawal of substrates and their substitution by others. In the present study we used gas chromatography coupled to mass spectrometry (GC-MS) to analyze how glioblastoma brain tumor cells respond metabolically when glucose is withdrawn and substituted by pyruvate.

METHODS

Glioblastoma brain tumor cells were cultivated in medium with high (25 mM), medium (11 mM) or low (5.5 mM) glucose concentration or with pyruvate (5 mM). After 24 h GC-MS metabolite profiling was performed.

RESULTS

The abundances of most metabolites were dependent on the supply of glucose in tendency but not in a linear manner indicating saturation at high glucose. Noteworthy, a high level of sorbitol production and release was observed at high concentrations of glucose and high release of alanine, aspartate and citrate were observed when glucose was substituted by pyruvate. Intermediates of the TCA cycle were present under all nutritional conditions and evidence was found that cells may perform gluconeogenesis from pyruvate.

CONCLUSIONS

Our experiments reveal a high plasticity of glioblastoma cells to changes in nutritional supply which has to be taken into account in clinical trials in which specific diets are considered for therapy.

Specific inhibition by synthetic analogs of pyruvate reveals that the pyruvate dehydrogenase reaction is essential for metabolism and viability of glioblastoma cells

The pyruvate dehydrogenase complex (PDHC) and its phosphorylation are considered essential for oncotransformation, but it is unclear whether cancer cells require PDHC to be functional or silenced. We used specific inhibition of PDHC by synthetic structural analogs of pyruvate to resolve this question. With isolated and intramitochondrial PDHC, acetyl phosphinate (AcPH, K_i^AcPH = 0.1 μM) was a much more potent competitive inhibitor than the methyl ester of acetyl phosphonate (AcPMe, K_i^AcPMe = 40 μM). When preincubated with the complex, AcPH also irreversibly inactivated PDHC. Pyruvate prevented, but did not reverse the inactivation. The pyruvate analogs did not significantly inhibit other 2-oxo acid dehydrogenases. Different cell lines were exposed to the inhibitors and a membrane-permeable precursor of AcPMe, dimethyl acetyl phosphonate, which did not inhibit isolated PDHC. Using an ATP-based assay, dependence of cellular viability on the concentration of the pyruvate analogs was followed. The highest toxicity of the membrane-permeable precursor suggested that the cellular action of charged AcPH and AcPMe requires monocarboxylate transporters. The relevant cell-specific transcripts extracted from Gene Expression Omnibus database indicated that cell lines with higher expression of monocarboxylate transporters and PDHC components were more sensitive to the PDHC inhibitors. Prior to a detectable antiproliferative action, AcPH significantly changed metabolic profiles of the investigated glioblastoma cell lines. We conclude that catalytic transformation of pyruvate by pyruvate dehydrogenase is essential for the metabolism and viability of glioblastoma cell lines, although metabolic heterogeneity causes different cellular sensitivities and/or abilities to cope with PDHC inhibition.

4.3 μm quantum cascade detector in pixel configuration

We present the design simulation and characterization of a quantum cascade detector operating at 4.3μm wavelength. Array integration and packaging processes were investigated. The device operates in the 4.3μm CO₂ absorption region and consists of 64 pixels. The detector is designed fully compatible to standard processing and material growth methods for scalability to large pixel counts. The detector design is optimized for a high device resistance at elevated temperatures. A QCD simulation model was enhanced for resistance and responsivity optimization. The substrate illuminated pixels utilize a two dimensional Au diffraction grating to couple the light to the active region. A single pixel responsivity of 16mA/W at room temperature with a specific detectivity D^* of 5⋅10⁷ cmHz/W was measured.

[Participation in Preventive Medical Examinations for Children in Saxony-Anhalt (Germany) at the Time of School Entry Medical Examination]

OBJECTIVE

The aim of this study is to present data concerning children's participation in the German preventive medical examinations for children ("U2" to "U8") in accordance with sections 26 and 92 of the German Social Code (Book V) as retrospectively recorded by the Public Health Service ("Öffentlicher Gesundheitsdienst") of the German Province of Saxony-Anhalt during school entry medical examinations. Also we wanted to analyse the additional variables recorded per child in the areas of social factors, diagnostic findings and levels of therapeutic care in connection with their degree of participation in the preventive medical examinations.

METHODOLOGY

The statistical analysis of 73 628 anonymised data sets from the health monitoring system of the German Province of Saxony-Anhalt that were collected by the 14 health authorities in Saxony-Anhalt during school entry medical examinations between 2008 and 2012. An analysis of the data for 20 variables per child was performed with regard to the influence of their degree of participation in the U2 to U8 medical examinations using differences in frequency in the examination groups and checking the significance of these differences by means of the chi-squared test.

RESULTS

99-96% of children in Saxony-Anhalt underwent the 5 preventive medical examinations U2-U6. As the children get older, the participation rates decrease (U2=98.7% down to U8=88.5%). By the time the school entry medical examinations are carried out (at an average age of 63 months), 83% of the children have -undergone all 7 preventive medical examinations for children, while 0.4% have not -undergone one single "U" examination. A child's gender has no influence on its parents' decision as to whether or not it should undergo the examinations. The results also reveal that children who attend day care -facilities are significantly more likely to have undergone all of the U examinations (84.8%) than children who are cared for at home (55.1%).

CONCLUSION

The retrospective comprehensive collection of data concerning the children's degree of participation in preventive medical examinations using the school entry medical examination is suitable for identifying connections between participation rates and the social factors, diagnostic findings and levels of therapeutic care of the children in question.

Zum System Bi2O3 /Bi2Se3/BiCl3,I. Das Zustandsdiagramm Bi2O3/Bi2Se3/BiCl3/On the System Bi2O3/Bi2Se3/BiCl3, I. The Phase Diagram Bi2O3/Bi2Se3/BiCl3

The phase relations in the quaternary system Bi/Se/O/Cl have been studied and the existence of several new compounds in the pseudotemary area Bi2O3/Bi2Se3/BiCl3 has been established by solid state and chemical vapour transport reactions. The phase diagram is derived from X-ray powder diffraction and thermal analysisdata, and from measurements of the decomposition pressure behaviour. Three new quaternary phases with different compositions exist in the system: Bi4O4SeCl2, Bi10O12SeCl4 and Bi22O28SeCl8.

By estimation of the thermodynamic data of the quaternary phases it is possible to calculate complex heterogeneous chemical equilibria between all the binary, ternary and quaternary compounds of the phase diagram. As a result, we can describe thermodynamically the observed phase relations and the direction of thermal decomposition of the respective compounds.

Zum Chemischen Transport von Rhenium und Rheniumoxiden/On the Chemical Transport of Rhenium and Rhenium Oxides

Synthesis and single crystal growth by chemical transport reactions of rhenium and rhenium oxides is reported. Several transport agents like the mercury halides HgCl2, HgBr2, HgI2, tellurium tetrachloride and iodine have been employed the transport of the rhenium compounds. Mass spectrometric experiments gave informations about the composition of the gas phase. The transport reactions were traced by calculations based on the knowledge of the gas phase species and their thermodynamical data.

Thermische Zersetzung und Lösungskalorimetrie von Ammoniumneodymchloriden/Thermal Decomposition and Solution Calorimetry of Ammonium Neodymium Chlorides

The thermodynamical data of ammonium neodymium chlorides (NH4)2NdCl5 and NH4Nd2Cl7 were derived by the determination of their decomposition equilibria by total pres­sure measurements. Moreover, solution calorimetry was applied. The enthalpies of formation of these phases were calculated from their heats of solution and from the enthalpies of formation and the heats of solution of NdCl3 and NH4Cl.

Data by total pressure measurement:

ΔH°B((NH4)2NdCl5,f,298) = - 412,5 ± 3,6 kcal/mol;

S°((NH4)2NdCl5 f 298) = 80,1 ± 5,8 cal/K · mol;

ΔH°B(NH4Nd2Cl7,f,298) = -579,5 ± 3,5 kcal/mol;

S°(NH4Nd2Cl7,f,298) 101,8 ± 5,6 cal/K mol.

Data by solution calorimetry:

ΔH°B(NdCl3,f,298) = -251,2 ± 0,7 kcal/mol;

ΔH°B((NH4)2NdCl5,f,298) = -405,5 ± 1,0 kcal/mol;

ΔH°B(NH4Nd2Cl7,f, 298) = -576,8 ± 1,7 kcal/mol.

Thermochemisches und kalorisches Verhalten von NdAl3Cl12 / Thermochemical and Calorical Behaviour of NdAl3Cl12

The thermodynamical data of solid and gaseous aluminium neodymium chloride have been obtained by determination of the decomposition equilibria (of solid) from total pressure measurements and chemical transport reactions (gaseous). The melting diagram was determined by DTA. The enthalpy of formation of the solid phase was calculated from their heats of solution and from the enthalpies of formation and the heats of solution of NdCl3 and AlCl3.

Data by total pressure measurement:

ΔH°B |(NdAl3Cl12,f,298) = -749,6 ± 2,5 kcal/mol; S°(NdAl3Cl12,f,298) = 118,2 ± 3,0 cal/K·mol.

Data by solution calorimetry: ΔH°B(NdAl3Cl12,f,298) = -748,6 ± 1,3 kcal/mol.

Data by chemical transport:

ΔH°B(NdAl3Cl12,g,298) = -701,5 ± 3,0 kcal/mol; S°(NdAl3Cl12,g,298) = 215,0 ± 4,0 cal/K-mol.

Thermische Zersetzung und Lösungskalorimetrie von Ammoniumneodymbromiden / Thermal Decomposition and Solution Calorimetry of Ammonium Neodymium Bromides

The thermal decomposition equilibria of ammonium neodymium bromides (NH4)3NdBr6, (NH4)2NdBr5 and NH4Nd2Br7 have been investigated by total pressure measurements. The thermodynamical data of these solid phase complexes have been derived from the decomposition functions. The standard enthalpies of solution in 4N HBr (aq.) of (NH4)3NdBr6, (NH4)2NdBr5, NH4Nd2Br7, NdBr3 and Nd2O3 were measured. On the basis of these values and tabulated data, the standard enthalpies at 298 K of the ammonium neodymium bromides were derived and compared with the results obtained from the total pressure measurements.

Data by total pressure measurement: ΔH°B((NH4)3 NdBr6,f,298) = -399,1 ± 4,9 kcal/mol; S°((NH4)3NdBr6,f,298) = 153,4 ± 7,4 cal/K.mol; ΔH°B((NH4)2NdBr5,f,298) = -343,0 ± 4,4 kcal/mol; S°((NH4)2,NdBr5,f,298) = 109,9 ± 6,8 cal/K.mol; ΔH°B(NH4Nd2Br7,f,298) = -484,0 ± 5,1 kcal/mol; S°(NH4Nd2Br7,f,298) = 127,9 ± 6,6 cal/K.mol.

Data by solution calorimetry: ΔH°B(NdBr3,f,298) = -208,7 ± 1,6 kcal/mol; ΔH°B((NH4)3- NdBr6,f,298) = -404,8 ± 2,7 kcal/mol; ΔH°B((NH4)2NdBr5,f,298) = -344,2 ± 2,4 kcal/mol; ΔH°B(NH4Nd2Br7,f,298) = -482,7 ± 3,7 kcal/mol.

Thermochemische Untersuchungen zu den Systemen SE2O3-SeO2. II. Samariumselenoxide auf dem Schnitt Sm2O3-SeO2 / Thermochemical Investigations of Systems SE2O3-SeO2. II. Samarium Selenium Oxides on the Line Sm2O3-SeO2

The pure ternary phases on the line Sm2O3-SeO2: Sm2SexO3+2x in thermodynamical equilibri­um have been synthesizied by solid state reactions and characterized by X-ray powder diffrac­tion, IR spectroscopy and DSC measurements. The existence of two new phases Sm2Se1,5O6 and Sm2Se4O11 was demonstrated besides the known phases Sm2Se3,5O10, Sm2Se3O9 and Sm2SeO5. The thermal decomposition properties of all compounds have been determined by total pressure measurements and the thermodynamical data of the compounds have been derived from their decomposition function and Cp-values. The phase diagram and the phase barogram have been estabilished using the results of DSC and total pressure measurements.

Phasenbeziehungen und Chemischer Transport der Verbindungen im ternären System Re/Mo/O / Phase Relations and Chemical Transport of the Compounds in the Ternary System Re/Mo/O

In the ternary system Re/Mo/O four series of mixed oxides have been prepared by heating of powder samples and by transport reactions. The series are derived from the oxides ReO2, MoO2, γ-Mo4O11 und η-Mo4-O11 and have compositions Re1-xMoxO2 (0 < x < 0.37), Mo1-yReyO2 (0 < y < 0.42),γ -Mo4-z1Rez1O11 (0 < z1 < 1), and η-Mo4-z2Rez2O11 (0 < z2 < 1). Contributions to the understanding of the transport mechanism were obtained from thermodynamic calculations. The composition of the mixed crystals obtained have been determined by EPMA and ICP-AES.

Zur Chemie von Mischphasen in komplexen Zustandsdiagrammen Das System Bi2O3/Bi2Se3/Bi2Te3/Chemistry of Mixed Crystals in Complex Phase Diagrams The System Bi2O3/Bi2Se3/Bi2Te3

Pseudoternary System Bi2O3/Bi2Se3/Bi2Te3, Phase Diagram, Thermodynamic Data The phase diagram of the pseudoternary system Bi2O3/Bi2Se3/Bi2Te3 is found to include a quaternary solid solution Bi2O2 (TexSe1-x) and ternary, intermetallic mixed crystals Bi2(TexSe1-x)3. Using thermodynamic modeling of the solid solutions it is possible to calcu­ late complex heterogeneous equilibria between all phases of this phase diagram. As a result we can thermodynamically describe the observed phase relations:

Bi2(TexSe1-x)3 ⊿H°m(298) = 0; ⊿S°m(298) = R[xlnx + (1-x)ln(1-x)]

Bi2O2(TexSe1-x) ⊿H°m(298) = Ω · x(1-x); O⊿S°m(298) = R/4 [xlnx + (1-x)ln(1-x)]

Ω = 0,6 kcal/mol

Verdampfungsverhalten von Lanthantrihalogeniden / Evaporation Behaviour of Lanthanum Trihalides

The evaporation of LaCl3, LaBr3 and Lal3 was investigated in closed tubes under argon atmosphere and correlated with data in the literature. The enthalpies and entropies of evaporation were derived from the temperature functions of pressure:

ΔH°(v, LaCl3, T) = 48,5 ± 2 kcal/mol, ΔS°(v, LaCl3, T) = 22,0 ± 3 cal/K-mol

ΔH°(v, LaBr3, T) = 48,0 ± 2 kcal/mol, ΔS°(v, LaBr3, T) = 24,0 ± 2 cal/K-mol

ΔH° (v , Lal3, T) = 49,5 ± 2 kcal/mol, ΔS°(v, Lal3,T) = 29,0 ± 2 cal/K-mol

Thermisches Verhalten von festem LaAlCl6 und chemischer Transport von LaCl3 mit AlCl3/Thermical Behaviour of Solid LaAlCl6 and Chemical Transport of LaCl3 with AlCl3

The thermodynamical data of solid aluminium lanthanum chloride LaAlCl6 have been obtained by determination of the decomposition equilibria from total pressure measurements. The melting diagram was determined by DTA. The chemical transport of LaCl3 with AlCl3 is suggesting the existence of the gaseous complex LaAl3Cl12. The data are:

ΔH(LaAlCl6 f,298) =-427,1 ±2,5 kcal/mol, S°(LaAlCl6,f,298) = 61 ±2,5 cal/K-mol,

Δ(LaAl3Cl12,g ,298) =-712 ± 7 kcal/mol, S°(LaAl3Cl12,g,298) = 205 ± 3 cal/K-mol.

Thermische Zersetzung und Lösungskalorimetrie von Ammoniumeuropiumchloriden / Thermal Decomposition and Solution Calorimetry of Ammonium Europium Chlorides

The thermal decomposition equilibria of ammonium europium chlorides (NH4)3EuCl6, (NH4)2EuCl5 and NH4Eu2Cl7 have been investigated by total pressure measurements in a membrane zero manometer. The thermodynamic data of these solid phases have been derived from the decomposition functions. The standard enthalpies of solution in 4n HCl (aq.) of (NH4)3EuCl6, (NH4)2EuCl5, NH4Eu2Cl7, EuCl3 and Eu2O3 were measured. On the basis of these values and tabulated data, the standard enthalpies at 298 K of the ammonium europium chlorides were derived and compared with the obtained results from the total pressure measurements.

Thermochemische Untersuchungen zu den Systemen SE2O3-SeO2. V. Ytterbiumselenoxide auf dem Schnitt Yb2O3-SeO2/Thermochemical Investigations of Systems RE2O3-SeO2. V. Ytterbium Selenium Oxides on the Line Yb2O3-SeO2

The pure ternary phases on the line Yb2O3-SeO2 in thermodynamical equilibrium have been synthesized by solid state reaction and characterized using X-ray powder diffraction and IR-spectroscopy. There exist three phases: Yb2SeO5, Yb2Se3O9 and Yb2Se4O11, the last one with a homogeneiety range extending a higher SeO2-content. The thermal decompositions have been determined by total pressure measurements, and the thermodynamical data of the compounds have been derived. The phase diagram and the phase barogram have been established using the results of thermal analysis and total pressure measurements.

Chemischer Transport intermetallischer Phasen III: Das System Co-Si / Chemical Vapour Transport of Intermetallic Phases III: The System Co -Si

Five phases exist in the system Co-Si: Co3Si, α- and β-Co2Si, CoSi and CoSi2. The phases α-Co2Si and CoSi could be prepared by chemical transport with iodine as transport agent in the temperature range between T1 (700 °C) and T2 (900 °C). In a attempted systematic clarification of the chemical transport reactions of all phases in the system, the effective transport equilibria were determined. Thermodynamic data show satisfactory agreement between calculation and experiment.

Calorimetrie an Yttriumtrihalogeniden und Yttriumoxidhalogemden / Calorimetry of Yttrium Trihalides and Yttrium Oxyhalides

The heats of solution of Yttrium, YOCL, YOBr, YOI, YCl3, YBr3, YI3 and Y2O3 were determined in 4n HX. From those the enthalpies of formation of Yttrium Trihalides YX3 and Yttrium Oxyhalides YOX at 298 K were derived:

ΔHB 0(YCl3,f,298) = -240.4 ± 0.6 kcal/mol, ΔHB 0(YBr3,f,298) = -202.1 ± 1.5 kcal/mol,

ΔHB 0(YI3,f ,298) = -147.0 ± 1.7 kcal/mol, ΔHB 0(YOClf,298) = -240.2 ± 1.0 kcal/mol,

ΔHB 0(YOBrf,298) = -229.7 ± 2.0 kcal/mol, ΔHB 0(YOIf ,298) = -208.8 ± 2.0 kcal/mol.

Thermische Zersetzung und Lösungskalorimetrie von Ammoniumsamariumchloriden/Thermal Decomposition and Solution Calorimetry of Ammonium Samarium Chlorides

We determined the decomposition equilibria of ammonium samarium chlorides (NH4)2SmCl5 and NH4Sm2Cl7 by total pressure measurements and derived their thermody­ namical data from the decomposition functions. The enthalpies of formation were compared with the results of the solution calorimetry. The heats of solution of all solid phases in the system SmCl3-NH4Cl and of Sm2O3 were measured in 4n HCl. The enthalpies of formation of ammonium samarium chlorides were derived from the enthalpies of formation of SmCl3 and of NH4Cl and their heats of solution.

Data by total pressure measurement

ΔH°B((NH4)2SmCl5,f,298) =-407,7 ± 2,9 kcal/mol;

S0((NH4)2SmCl5,f,298) = 84,0 ± 4,5 cal/K-mol;

ΔH°B((NH4)Sm2Cl7,f,298) = -576,8 ± 3,4 kcal/mol;

S°(NH4Sm2Cl7,f,298) = 98,1 ± 5,5 cal/K-mol.

Data by solution calorimetry

ΔH°B(SmCl3,f,298) = -248,1 ± 0,8 kcal/mol;

ΔH°B((NH4),SmCl5,f,298) = -404 ,3 ± 1,1 kcal/mol;

ΔH°B(NH4Sm9Cl7,f,298)= -572,3 ± 1,8 kcal/mol.

Untersuchungen zum ternären System Bi/Te/O, II. Thermisches Verhalten und Koexistenzbeziehungen von Bi2O2Te/Investigations of the Ternary System Bi/Te/O, II. The Thermal Behaviour and the Relations of Phase Coexistences of Bi2O2Te

The phase Bi2O2Te exists in the pseudobinary system Bi2O3/Bi2Te3. The thermal behaviour of Bi2O2Te was determined by DTA and X-ray analysis: The phase exists up to 620 °C and decomposes into the solid phases Bi12TeO20, Bi10Te2O19 [1] and liquid BiTe. The relations of the phase coexistences in the pseudobinary system and in the ternary area Bi2O3/TeO2/Bi2Te3/Te were investigated by solid state reactions, chemical transport reactions, and by total pressure measurements.

Thermochemische Untersuchungen zu den Systemen SE2O3-SeO2 IV. Lösungskalorimetrie der SE2SexO3+2x-Phasen (SE = Nd, Sm, Y) / Thermochemical Investigations on the Systems RE2O3-SeO2 IV. Solution Calorimetry of the Phases RE2SexO3+2x(RE =Nd, Sm, Y)

The solution enthalpies have been determined for the ternary phases RE2SexO3+2x existing on the pseudo-binary section RE2O3-SeO2 and for RE2O3 and SeO2 in 4n HCl (RE =Nd, Sm, Y). From these date the enthalpies of formation of the ternary phases have been derived via suitable solution schemes on the basis of the known enthalpies of formation of RE2O3 and SeO2.

Untersuchungen zum ternären System Bi/Te/O, III. Bestimmung thermodynamischer Daten der ternären Verbindungen/Investigations on the Ternary System Bi/Te/O,III. Determination of Thermodynamic Data of Ternary Compounds

The phase relations in the ternary system Bi/Te/O have been determined in previous studies by solid state reactions. Thermodynamical data have now been obtained for the pertinent equilibria. The heats of solution of Bi2O3, Bi12TeO20, Bi10Te2O19, Bi16Te5O34, Bi2TeO5, Bi2Te2O7, Bi2Te4O11 and TeCl4 were determined in 4N HCl. From these the enthalpies of formation of bismuth tellurites at 298 K have been derived:

⊿H°b (Bi12TeO20, f, 298) = -901,6 ± 8 kcal/mol,

⊿H°b (Bi10Te2O19, f, 298) = -856,1 ± 9 kcal/mol,

⊿H°b (Bi16Te5O34, f, 298) = -1519,5 ± 17 kcal/mol,

⊿H°b (Bi2TeO5, f, 298)= -222,8 ± 3 kcal/mol,

⊿H°b (Bi2Te2O7, f, 298)= -299,4 ± 4 kcal/mol,

⊿H°b (Bi2Te4O11, f, 298)= -448,2 ± 7 kcal/mol.

Calorimetrie an Ammoniumyttriumhalogeniden / Calorimetry of Ammonium Yttrium Halides

The heat of solution of all solid phases in the system YX3-NH4X with X = Cl, Br, I in 4n HX was investigated. The enthalpies of formation of the ammonium yttrium halides are derived from the enthalpies of formation of Y X3 and of NH4X and their heats of solution in An HX:

ΔHB 0(NH4Y2Cl7,f,298) = -561,5 ± 1,7 kcal/mol, ΔHB 0((NH4)3 YCl6,f,298) = -474,5 ± 1,3 kcal/mol,

ΔHB 0((NH4)3YBr6,f,298) = -400,8 ± 2,6 kcal/mol, ΔHB 0((NH4)3YI6,f,298) = -291,9 ± 3,0 kcal/mol.

Untersuchungen zum chemischen Transport von YX3 mit AlX3 und zur Existenz von gasförmigen und festen Komplexen YAl3 X12 (X = Br, I) / Investigations on the Chemical Transport Reaction of YX3 with AlX3 and on the Existence of Gaseous and Solid Complexes YAl3 X12 (X = Br, I) H

The dominant gaseous complexes YAl3Br12 and YAl3I12 were generated in the chemical trans­port reactions of YBr3 with AlBr3 and YI3 with AlI3. The enthalpy of formation

ΔH0 B(YAl3Br12,g,298) = -484,5 ± 6 kcal/mol

and the standard entropy

S°(YA13B12,g,298) = 290,0 ± 7,5 cal/K·mol

have been calculated. It follows from total pressure measurements of mixtures of YBr3,s with AlBr3,1 and YI3,s with AlI3,1 respectively, that complexes YAl3Br12,s and YAl3I12,s do not exist up to the boiling points of the aluminium trihalides.

Chemischer Transport intermetallischer Phasen, II: Das System Fe-Si/Chemical Vapour Transport of Intermetallic Phases, II: The System Fe-Si

Five phases exist in the system Fe-Si: Fe3Si, Fe2Si, Fe5Si3, FeSi, α-and β-FeSi2. All phases could be prepared by chemical transport with iodine as transport agent in the temperature range between T1 (700 °C) and T2 (1030 °C). In a attempted systematic clarification of the chemical transport reactions of all phases in the system, the effective transport equilibria were determined. Thermodynamic calculations show satisfactory agreement between calcula­tion and experiment.