CD4+ T cell activation distinguishes response to anti-PD-L1+anti-CTLA4 therapy from anti-PD-L1 monotherapy

Cancer patients often receive a combination of antibodies targeting programmed death-ligand 1 (PD-L1) and cytotoxic T lymphocyte antigen-4 (CTLA4). We conducted a window-of-opportunity study in head and neck squamous cell carcinoma (HNSCC) to examine the contribution of anti-CTLA4 to anti-PD-L1 therapy. Single-cell profiling of on- versus pre-treatment biopsies identified T cell expansion as an early response marker. In tumors, anti-PD-L1 triggered the expansion of mostly CD8+ T cells, whereas combination therapy expanded both CD4+ and CD8+ T cells. Such CD4+ T cells exhibited an activated T helper 1 (Th1) phenotype. CD4+ and CD8+ T cells co-localized with and were surrounded by dendritic cells expressing T cell homing factors or antibody-producing plasma cells. T cell receptor tracing suggests that anti-CTLA4, but not anti-PD-L1, triggers the trafficking of CD4+ naive/central-memory T cells from tumor-draining lymph nodes (tdLNs), via blood, to the tumor wherein T cells acquire a Th1 phenotype. Thus, CD4+ T cell activation and recruitment from tdLNs are hallmarks of early response to anti-PD-L1 plus anti-CTLA4 in HNSCC.

Exploring long-term responses to immune checkpoint inhibitors in recurrent and metastatic head and neck squamous cell carcinoma

OBJECTIVES

Immune checkpoint inhibitors (ICI) have introduced a new era in the treatment of recurrent and/or metastatic head and neck squamous cell carcinoma (R/M HNSCC). Optimal duration for ICI therapy is still unclear and the long-term outcomes and toxicity in patients responding to these therapies warrant further exploration. This study attempts to identify the clinical and biological determinants of a durable response and evaluate outcomes following ICI treatment discontinuation.

MATERIALS AND METHODS

A retrospective review of 181 patients treated with ICI for R/M HNSCC was conducted. Long-term responders were defined as patients who sustained disease control at least two years after initiating ICI therapy. We compared clinical and biological characteristics associated with these long-term responders against the broader treatment population.

RESULTS

10 % of R/M HNSCC patients treated with ICIs demonstrated a durable long-term response. Only three relapses (16 %) occurred after discontinuing ICI treatment in this subset, with a median follow-up of 52 months. Upon retreatment with ICI, two attained a documented response. Extended ICI response was observed even with < 2 years of treatment. 74 % of long-term responders experienced immune-related adverse events (irAEs), 37 % of which severe irAEs. Hypothyroidism was the most frequently reported irAEs. The predictive potential of systemic inflammation indices for clinical response appears to be limited.

CONCLUSIONS

ICI present an optimistic avenue for HNSCC patients, offering substantial long-term responses. The study suggests that a two-year treatment could be optimal and irAEs, although common, are typically mild.

Transcriptional and spatial profiling of the kidney allograft unravels a central role for FcyRIII+ innate immune cells in rejection

Rejection remains the main cause of premature graft loss after kidney transplantation, despite the use of potent immunosuppression. This highlights the need to better understand the composition and the cell-to-cell interactions of the alloreactive inflammatory infiltrate. Here, we performed droplet-based single-cell RNA sequencing of 35,152 transcriptomes from 16 kidney transplant biopsies with varying phenotypes and severities of rejection and without rejection, and identified cell-type specific gene expression signatures for deconvolution of bulk tissue. A specific association was identified between recipient-derived FCGR3A+ monocytes, FCGR3A+ NK cells and the severity of intragraft inflammation. Activated FCGR3A+ monocytes overexpressed CD47 and LILR genes and increased paracrine signaling pathways promoting T cell infiltration. FCGR3A+ NK cells overexpressed FCRL3, suggesting that antibody-dependent cytotoxicity is a central mechanism of NK-cell mediated graft injury. Multiplexed immunofluorescence using 38 markers on 18 independent biopsy slides confirmed this role of FcγRIII+ NK and FcγRIII+ nonclassical monocytes in antibody-mediated rejection, with specificity to the glomerular area. These results highlight the central involvement of innate immune cells in the pathogenesis of allograft rejection and identify several potential therapeutic targets that might improve allograft longevity.

Abstract 5785: A pan-cancer single-cell tumor micro-environment atlas predictive of immunotherapy response

The tumor microenvironment (TME) shapes response to immune checkpoint blockade (ICB). Several pan-cancer single-cell RNA-sequencing (scRNA-seq) analyses have reported how TME heterogeneity profoundly differs between cancer types. These studies mainly focused on one cell type (e.g., T-cells) and combined different technologies and bioinformatics pipelines with data being collected from both published and newly generated datasets. A comprehensive pan-cancer scRNA-seq map of the TME involving all cell types is therefore still lacking.

We obtained scRNA-seq (10x Genomics) on 234 fresh tissue samples from 161 treatment-naïve patients. Samples were collected from 9 cancer types and subjected to a uniform in-house optimized protocol of tissue dissociation, sequencing and bioinformatics analysis. Abundancies of cell types and subtypes were correlated with each other and a tumor-reactive T-cell signature.

From 683,184 high-quality single cells, we identified 9 cell types and 71 subtypes of T-cells, B-cells, dendritic cells (DCs), monocytes/macrophages and endothelial-cells (ECs), shared between cancer types. PDCD1 (PD1) was expressed by differentiated T-cells subtypes (e.g., CD8+ exhausted and CD4+ T-helper-1 subclusters), while CD274 and PDCD1LG (PDL-1/PDL-2) were mainly expressed by regulatory B-cells, immune-regulatory DCs, CXCL10+ and CCL2+ monocyte-derived macrophages as well as inflammatory ECs. Pairwise analyses showed positive correlations between PD1-expressing T-cell subclusters, CD4+ T-regulatory cells, plasma B-cells (plasmablasts, IgA and IgG plasma cells), immune-regulatory DCs, CXCL10+ and CCL2+ macrophages and lymphatic ECs. On the other hand, negative correlations were observed with naïve T- and B-cells, conventional DC2 (cDC2), monocytes, CX3CR1+ macrophages, as well as arterial and capillary ECs. When ranking individual tumors based on a tumor-reactive T-cell signature, we found reactive tumors to correlate with positively interacting subtypes, while they anti-correlated with subclusters negatively interacting with PD1-expressing differentiated T-cells. Upon deconvolution of bulk RNA-seq data using gene signatures derived from each subcluster, these correlations were replicated in TCGA datasets across cancers. These signature scores correlated with tumor mutation burden (TMB) and other immunological features, while they were also predictive of response in clinical trials involving ICB.

We provide insights into the TME complexity at unprecedented level, identifying numerous subclusters enriched in immune-reactive (hot) or -suppressive (cold) tumors across cancer types. We validate these observations in TCGA by deconvolution of bulk RNA-seq data, and show that already pre-treatment several TME subclusters predict response to ICB.

Citation Format: Francesca Lodi, Sam Vanmassenhove, Elena Donders, Pierre Van Mol, Amelie Franken, Sarah Cappuyns, Ayse Bassez, Siel Olbrecht, Liselore Loverix, Michel Bila, Hanne Vos, Joanna Pozniak, Kevin Punie, Diether Lambrechts. A pan-cancer single-cell tumor micro-environment atlas predictive of immunotherapy response. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5785.

Single-cell transcriptomics identifies pathogenic T-helper 17.1 cells and pro-inflammatory monocytes in immune checkpoint inhibitor-related pneumonitis

Background

Immune checkpoint inhibitor (ICI)-related pneumonitis is the most frequent fatal immune-related adverse event associated with programmed cell death protein-1/programmed death ligand-1 blockade. The pathophysiology however remains largely unknown, owing to limited and contradictory findings in existing literature pointing at either T-helper 1 or T-helper 17-mediated autoimmunity. In this study, we aimed to gain novel insights into the mechanisms of ICI-related pneumonitis, thereby identifying potential therapeutic targets.

Methods

In this prospective observational study, single-cell RNA and T-cell receptor sequencing was performed on bronchoalveolar lavage fluid of 11 patients with ICI-related pneumonitis and 6 demographically-matched patients with cancer without ICI-related pneumonitis. Single-cell transcriptomic immunophenotyping and cell fate mapping coupled to T-cell receptor repertoire analyses were performed.

Results

We observed enrichment of both CD4+ and CD8+ T cells in ICI-pneumonitis bronchoalveolar lavage fluid. The CD4+ T-cell compartment showed an increase of pathogenic T-helper 17.1 cells, characterized by high co-expression of TBX21 (encoding T-bet) and RORC (ROR-γ), IFN-G (IFN-γ), IL-17A, CSF2 (GM-CSF), and cytotoxicity genes. Type 1 regulatory T cells and naïve-like CD4+ T cells were also enriched. Within the CD8+ T-cell compartment, mainly effector memory T cells were increased. Correspondingly, myeloid cells in ICI-pneumonitis bronchoalveolar lavage fluid were relatively depleted of anti-inflammatory resident alveolar macrophages while pro-inflammatory ‘M1-like’ monocytes (expressing TNF, IL-1B, IL-6, IL-23A, and GM-CSF receptor CSF2RA, CSF2RB) were enriched compared with control samples. Importantly, a feedforward loop, in which GM-CSF production by pathogenic T-helper 17.1 cells promotes tissue inflammation and IL-23 production by pro-inflammatory monocytes and vice versa, has been well characterized in multiple autoimmune disorders but has never been identified in ICI-related pneumonitis.

Conclusions

Using single-cell transcriptomics, we identified accumulation of pathogenic T-helper 17.1 cells in ICI-pneumonitis bronchoalveolar lavage fluid—a phenotype explaining previous divergent findings on T-helper 1 versus T-helper 17 involvement in ICI-pneumonitis—, putatively engaging in detrimental crosstalk with pro-inflammatory ‘M1-like’ monocytes. This finding yields several novel potential therapeutic targets for the treatment of ICI-pneumonitis. Most notably repurposing anti-IL-23 merits further research as a potential efficacious and safe treatment for ICI-pneumonitis.

ViBiBa: Virtual BioBanking for the DETECT multicenter trial program - decentralized storage and processing

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ViBiBa is an open-source sample banking tool.

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ViBiBa was purpose built for liquid biopsy specimen.

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ViBiBa allows for decentralized storage while promoting collaboration.

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ViBiBa's plugin support requires no change in existing data structures.

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ViBiBa empowers translational research projects and cohort formation.

Background

Liquid Biopsy (LB) in the form of e.g., circulating tumor cells (CTCs) is a promising non-invasive approach to support current therapeutic cancer management. However, the proof of clinical utility of CTCs in informing therapeutic decision-making for e.g., breast cancer in clinical trials and associated translational research projects is facing the issues of low CTC positivity rates and low CTC numbers – even in the metastasized situation. To compensate for this dilemma, clinical CTC trials are designed as large multicenter endeavors with decentralized sample collection, processing and storage of products, making data management highly important to enable high-quality translational CTC research.

Aim

In the DETECT clinical CTC trials we aimed at developing a custom-made, browser-based virtual database to harmonize and organize both decentralized processing and storage of LB specimens and to enable the collection of clinically meaningful LB sample.

Methods

ViBiBa processes data from various sources, harmonizes the data and creates an easily searchable multilayered database.

Results

An open-source virtual bio-banking web-application termed ViBiBa was created, which automatically processes data from multiple non-standardized sources. These data are automatically checked and merged into one centralized databank and are providing the opportunity to extract clinically relevant patient cohorts and CTC sample collections.

Summary

ViBiBa, which is a highly flexible tool that allows for decentralized sample storage of liquid biopsy specimens, facilitates a solution which promotes collaboration in a user-friendly, federalist and highly structured way. The source code is available under the MIT license from https://vibiba.com or https://github.com/asperciesl/ViBiBa

Reflections on the OECD guidelines for in vitro skin absorption studies

At the 8th conference of Occupational and Environmental Exposure of the Skin to Chemicals (OEESC) (16-18 September 2019) in Dublin, Ireland, several researchers performing skin permeation assays convened to discuss in vitro skin permeability experiments. We, along with other colleagues, all of us hands-on skin permeation researchers, present here the results from our discussions on the available OECD guidelines. The discussions were especially focused on three OECD skin absorption documents, including a recent revision of one: i) OECD Guidance Document 28 (GD28) for the conduct of skin absorption studies (OECD, 2004), ii) Test Guideline 428 (TGD428) for measuring skin absorption of chemical in vitro (OECD, 2004), and iii) OECD Guidance Notes 156 (GN156) on dermal absorption issued in 2011 (OECD, 2011). GN156 (OECD, 2019) is currently under review but not finalized. A mutual concern was that these guidance documents do not comprehensively address methodological issues or the performance of the test, which might be partially due to the years needed to finalize and update OECD documents with new skin research evidence. Here, we summarize the numerous factors that can influence skin permeation and its measurement, and where guidance on several of these are omitted and often not discussed in published articles. We propose several improvements of these guidelines, which would contribute in harmonizing future in vitro skin permeation experiments.

A pan-cancer blueprint of the heterogeneous tumor microenvironment revealed by single-cell profiling

The stromal compartment of the tumor microenvironment consists of a heterogeneous set of tissue-resident and tumor-infiltrating cells, which are profoundly moulded by cancer cells. An outstanding question is to what extent this heterogeneity is similar between cancers affecting different organs. Here, we profile 233,591 single cells from patients with lung, colorectal, ovary and breast cancer (n = 36) and construct a pan-cancer blueprint of stromal cell heterogeneity using different single-cell RNA and protein-based technologies. We identify 68 stromal cell populations, of which 46 are shared between cancer types and 22 are unique. We also characterise each population phenotypically by highlighting its marker genes, transcription factors, metabolic activities and tissue-specific expression differences. Resident cell types are characterised by substantial tissue specificity, while tumor-infiltrating cell types are largely shared across cancer types. Finally, by applying the blueprint to melanoma tumors treated with checkpoint immunotherapy and identifying a naïve CD4⁺ T-cell phenotype predictive of response to checkpoint immunotherapy, we illustrate how it can serve as a guide to interpret scRNA-seq data. In conclusion, by providing a comprehensive blueprint through an interactive web server, we generate the first panoramic view on the shared complexity of stromal cells in different cancers.

Abstract P3-01-12: Clinical safety of diagnostic leukapheresis as a liquid biopsy to collect circulating tumor cells in primary and metastatic breast cancer patients

Introduction: The enumeration of circulating tumor cells (CTCs) has been shown to be of prognostic relevance for neoadjuvant, adjuvant and metastatic setting of breast cancer in multiple clinical trials. Moreover, the serial determination of CTCs enables therapy monitoring in the metastatic setting. One major caveat is the low number of CTCs detected by established methods which limits the possibility for further evaluation including phenotyping and genotyping. Therefore, the clinical use of CTCs as liquid biopsy for making therapy decisions is still under discussion. Diagnostic leukapheresis (DLA) has been previously established by our research group and implemented in the workflow for isolation and detection of CTCs enabling a reliable detection of CTCs at high frequency. The aim of this clinical study was to assess the safety of leukapheresis in 39 patients with primary and metastatic breast cancer.

Methods: DLA was performed at least 1d before surgery or chemotherapy. A median blood volume of 2.7 L (range, 1.0 L–5.3 L) was processed. Citrate dextrose solution A was used for anticoagulation with ratios ranging from 11:1 to 24:1. Complete blood count as well as measuring blood pressure and heart rate was performed before start of DLA and immediately after DLA. CTCs were enumerated using the CellSearch system. DLA products containing a median number of 1,8x108 MNCs were processed.

Results: 41 patients were eligible for DLA. Only in two patients DLA could not be performed due to technical problems. Thirty-nine patients underwent leukapheresis. Twenty-six patients had non metastatic breast cancer. Thirteen patients were diagnosed with metastatic breast cancer. Severe adverse events including hypotension, nauseas, tingling e.g. resulting in interruption of apheresis were not observed. The DLA did not interfere with the start of chemotherapy or surgery. Complete blood count before and after DLA showed statistic significant but clinically irrelevant decrease in numbers of leukocytes, thrombocytes, hemoglobin and the percentage of hematocrit. In 11/21 DLA samples (52%) of patients with primary breast cancer CTCs were detected. Number of CTCs ranged from 1 to 51. In 11/13 DLA samples (85%) of patients with MBC CTCs were detected. Number of CTCs ranged from 1 to 2913.

Conclusion: Establishing a routine DLA protocol we demonstrated that this procedure is clinically safe and can be implemented into the clinical workflow of breast cancer patient care.

Citation Format: Fehm T, Meier-Stiegen F, Jaeger B, Reinhardt F, Naskou J, Franken A, Neubauer H, Driemel C, Ruckhaeberle E, Niederacher D, Fischer J, Stoecklein N. Clinical safety of diagnostic leukapheresis as a liquid biopsy to collect circulating tumor cells in primary and metastatic breast cancer patients [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-01-12.

Darstellung, Schwingungsspektren und Normalkoordinationsanalyse der D- und 13C-Isotopomeren des Methylpentahydro-closo-hexaborats [B6H5(CH3)]2- sowie Kristallstruktur von [P(C6H5)4][B6H6(CH3)] / Preparation, Vibrational Spectra and Normal Coordinate Analysis of the D and 13C Isotopomeres of the Methylpentahydro-closo-hexaborate [B6H5(CH3)]2- and the Crystal Structure of [P(C6H5)4][B6H6(CH3)]

The crystal structure of [P(C6H5)4][B6H6(CH3)] has been determined by single crystal X-ray diffraction analysis; triclinic space group P 1̄ with a = 7.408(2), b = 11.887(3), c = 14.4486(9) Å , α = 80.013(12), β = 79.421(10), γ = 88.85(2)°. The additional H atom could be refined with B - H distances between 1.21 and 1.31 Å above one of the facettes of the B6 octahedron adjacent to the methyl group. The IR and Raman spectra of the ueprotonated Cs salts of the six isotopomers [B6H5(CH3)]2-, [B6H5(CD3)]2-, [B6H5(13CH3)]2-, [B6D5(CH3)]2-, [B6D5(CD3)]2- and [B6D5(13CH3)]2- exhibit characteristic shifts of their vibration bands. Using the crystallographic data a normal coordinate analysis has been performed, based on a general valence force field. With a set of 14 force constants (e.g. fd(BB ) = 1.80, fd(BC ) = 3.70, fd(BH ) = 3.17, fd(CH ) = 4.62 mdyn/Å) good agreement between observed and calculated frequencies o f all D and 13C isotopically labeled derivatives has been achieved. The potential energy distribution on the force constants reveals strong vibrational couplings of the boron cage with the substituents. The B - C stretching vibration o f the CH3 group is observed in the region 1142-1153 cm-1, for the CD3 substituent at higher frequencies of 1168-1179 cm-1.

Darstellung und 11B-NMR-Spektrum von Heptabromo-closo-heptaborat, [B7Br7]2- sowie Kristallstruktur von [(C5H5N)2CH2][B7Br7] / Preparation and 11B NMR Spectrum of Heptabromo-closo-heptaborate, [B7Br7]2-, and the Crystal Structure of [(C5H5N)2CH2][B7Br7]

By reaction of conjuncto-[B6H6-B6H6]2- in alkaline solution with excess bromine the heptabromo-closo-heptaborate, [B7Br7]2 is formed. The crystal structure of [(CsH3N)2CH2][B7Br7] has been determined by single crystal X-ray diffraction analysis (monoclinic, space group P21/a with a = 15.0843(14), b = 9.8882(14), c = 17.057(2) Å, β = 114.039°(7)). In accordance with the D5h point symmetry, the anion shows two singlets at -23.3 and -0.1 ppm with the intensity ratio 2:5 in its 11B NMR spectrum.

Darstellung, 11B-NMR- und Schwingungsspektren von μ-Distickstoff-bis(pentahydro-closo-hexaborat)(2-), [B6H5(NN)B6H5]2-sowie Kristallstruktur von [As(C6H5)4]2[B6H5(NN)B6H5] / Preparation, 11B NMR and Vibrational Spectra of μ-Dinitrogen-bis(pentahydro-closo-hexaborate)(2-), [B6H5(NN)B6H5]2 and the Crystal Structure of [As(C6H5)4]2[B6H5(NN)B6H5]

By reduction of [B6H5(NO2)]2- with aluminium powder in aqueous alkaline solution the orange μ-dinitrogen-bis(pentahydro-closo-hexaborate)(2-), [B6H5(NN)B6H5]2-, is formed, which can be precipitated with tetraphenylarsonium ions. The crystal structure of [As(C6H5)4]2[B6H5(NN)B6H5] has been determined by single crystal X-ray diffraction analy­sis; tetragonal, space group P4/n with a = 12.6610(12), c = 14.6790(11) Å. The B6 cages are slightly compressed (2%) in the direction of the connecting linear N2 bridge with bond lengths N-N of 1.129 and B-N of 1.421 Å. The 11B NMR spectrum exhibits signals at -27.0 (ipso-B), +1.26 (equatorial-B), +3.54 ppm (antipodal-B atoms). The NN stretching vibration is observed in the Raman spectra as a very strong line at 2065 cm-1.

Darstellung, 11B-NMR-Spektren, Schwingungsspektren und Normalkoordinatenanalyse von conjuncto-Bis-hexahydro-closo-hexaborat, [B6H6-B6H6]2-, sowie Kristallstruktur von [P(C6H5)4]2-conjuncto-[B6H6-B6H6] / Preparation, 11B NMR Spectra, Vibrational Spectra and Normal Coordinate Analysis of conjuncto-Bis-hexahydro-closo-hexaborate, [B6H6-B6H6]2-, and the Crystal Structure of [ P(C6H5)4]2-conjuncto-[B6H6-B6H6]

By reaction of [B6H6]2- with dibenzoylperoxide in dichloromethane conjuncto-[B6H6- B6H6]2- is formed. The product could be separated from excess [B6H6]2- by ion exchange chromatography on diethylaminoethyl cellulose. The crystal structure of [P(C6H5)4]2 -conjuncto- [B6H6-B6H6] has been determined by single crystal X-ray diffraction analysis; triclinic, space group P1̄ with a = 10.8315(10), b = 11,2422( 12), c = 20.340(2) Å, α = 91.278° (9), β = 90.178° (9), γ = 105.662°(9). The 11B NMR spectrum reveals three signals with the intensity ratio 1:1:4, for two equivalent moieties of the conjuncto molecule ion with local C4v symmetry. The IR and Raman spectra of the deprotonated Cs salts of the 10B, 11B and their respective D isotopomers of conjuncto-[B6H5-B6H5]4- exhibit characteristic shifts. Using averaged crystallographic data and assuming idealized D4h symmetry, normal coordinate analyses have been performed based on a modified valence force field. With a set of eleven force constants (e.g. fd(BB)conjuncto = 2.9, fd(BB)cage = 1.6 mdyn/Å) very good agreement between observed and calculated frequencies has been achieved. From strong vibrational coupling with the B6 clusters two vibrations result for the conjuncto B-B bond at 1142/1198 and 292/304cm-1 for 11B/10B species, respectively. They can be assigned as anti-phase and in-phase motions of the conjuncto B atoms related to the equatorial B4 planes.

Darstellung, 11B-, 13C-NMR-und Schwingungsspektren von Cyanomethylhexahydro-closo-Hexaborat(Hexaborat(1-), [B6H6(CH2CN)]– sowie Kristallstruktur von [P(C6H5)4][B6H6(CH2CN)] / Preparation, 11B, 13C NMR and Vibrational Spectra of Cyanomethylhexahydro-closohexaborate(1-), [B6H6(CH2CN)]- and the Crystal Structure of [P(C6H5)4][B6H6(CH2CN)]

By reaction of [B6H6]2- with chloroacetonitrile in dichloromethane the cyanomethylhexahy-dro-closo-hexaborate(1-), [B6H6(CH2CN)]- is formed. The com pound has been separated from excess [B6H6]2- by ion exchange chromatography on diethylaminoethyl cellulose. The crystal structure of [P(C6H5)4][B6H6(CH2CN)] has been determined by single crystal X-ray diffraction analysis; triclinic, space group P1 with a = 7.503(3), b = 12.0949(8), c = 14.6572(11) Å α = 79.399(6)°, β = 79.19(2)°, γ = 89.2(2)°. The 11B NMR spectrum is consistent with a mono hetero substituted octahedral B6 cage. In the 13C NMR spectrum of Cs2[B6H5(CH2CN)] a singlet at 131.9 ppm (CN) and a quartet at 2.97 ppm with 1J(C,B) = 54.7 Hz (CH2) are observed. The IR and Raman spectra exhibit a very strong CN stretching band at 2218 cm-1.

Darstellung, 11B-, 13C-NMR-und Schwingungsspektren von Aminom ethylhexahydro-closo-hexaborat(1-), [B6H6(CH2NH2)]- sowie Kristallstrukturen von Cs[B6H6(CH2NH2)] und K[B6H6(CH2NH2)] / Preparation, 11B, 13C NMR and Vibrational Spectra of Aminomethylhexahydro-closo-hexaborate(1-), [B6H6(CH2NH2)]-, and Crystal Structures of Cs[B6H6(CH2NH2)] and K[B6H6(CH2NH2)]

By reaction of [B6H6]2- with N-(chloromethyl)phthalimide in dichloromethane the intermediate phthalimidomethylhexahydro-closo-hexaborate(1-), [B6H6(CH2(NC8O2H4)]-, is formed which with an excess of hydrazine reacts to give am inomethylhexahydro-closo-hexaborate(1-). The crystal structures of Cs[Bf,H6(CH2NH2)] and K[B6H6(CH2NH2)] have been determined by single crystal X -ray diffraction analysis. They are monoclinic, space group C2/m with a = 11.123(6), b = 6.8441(11), c = 12.810(7) Å, β = 124.032(5)° for Cs[B6H6(CH2NH2)] and with a = 10.767(2), b = 6.6255(6), c = 12.2648(14) Å, β = 123.880(10")° for K [B6H6(CH2NH2)]. The 11B NMR spectrum is consistent with a monohetero substituted octahedral B6 cage with local C4v symmetry. In the 13C NMR spectrum of Cs[B6H6(CH2NH2)] a quartet at 32.7 ppm with 1J(C,B) 65 Hz is observed. The IR and Ram an spectra exhibit characteristic CH, NH, BH and B6 vibrations

Darstellung, 11B-NMR- und Schwingungsspektren mehrfach alkylierter closo-Hexaborate und Kristallstruktur von cis- und trans-[P(C6H5)4][B6H5(CH3)2] sowie mer-[P(C6H5)4][B6H4(CH3)3] / Preparation, 11B NMR and Vibrational Spectra of Multialkylated Hexaborates and Crystal Structures of cis- and trans-[P(C6H5)4][B6H5(CH3)2] and mer-[P(C6H5)4][B6H4(CH3)3]

By treatment of protonated monoalkyl-closo-hexaborates [B6H6R]-. R = CH3, C2H5, n-C3H7, i-C3H7 in aqueous alkaline solution with [As(C6H5)4]Cl the yellow orange deprotonated tetraphenylarsonium salts are precipitated, which react with methyl iodide or ethyl iodide to give dialkylated and protonated B6-compounds. The cisltrans isomers formed in a 1:1 ratio have been separated by ion exchange chromatography on diethylam inoethyl cellulose. Repeated deprotonation and reaction with methyl iodide affords mer-[B6H4 (CH3)3]-. The crystal structures of cis-[P(C6H5)4][B6H5(CH3)2] (I), trans-[P(C6H5)4][B6H5(CH3)2] (II) and mer-[P(C6H5)4][B6H4(CH3)3](III) have been determined by single crystal X-ray diffraction analyses; I and II are monoclinic, space group P2/n, I with a = 11.8690(5), b = 7.2575(7), c = 15.8689(3) Å , β = 111.454(17)°; II with a = 13.2853(7), b = 7.4608(8), c = 13.3549(11), β = 93.5(11); III is tetragonal, space group P4/n with a = 13.363(2), c = 7.5051(13). The three methyl substituents are statistically distributed over four equatorial positions of the B6 cage. The 11B NMR spectra of the di- and trialkylated com pounds exhibit shifts of ipso-B atoms to lower, of antipodal-B atoms to higher field compared with [B6H7]-. The IR and Raman spectra of the di- and trimethyl derivatives are similar to those of monom ethylhexaborate.

Darstellung, 11B-, 13C-NMR- und Schwingungsspektren der closo-Hexaborate [B6H5(CN)12- und cis-[B6H4(CN)2]2− sowie Kristallstruktur von Cs2[B6H5(CN)] / Preparation, 11B,13C NMR and Vibrational Spectra of the closo-Hexaborates [B6H5(CN)]2- and cis-[B6H4(CN)2]2-, and the Crystal Structure of Cs2[B6H5(CN)]

By reaction of Cs2[B6H6] with in situ generated dicyanogen in aqueous alkaline solution the monocyanohydrohexaborate Cs2[B6H5(CN)] and the dicyanohydrohexaborate cis-Cs2[B6H4(CN)2] are formed. The compounds have been separated by ion exchange chromatography on diethylaminoethyl cellulose. The crystal structure of Cs2[B6H5(CN)] was determined from single crystal X-ray diffraction analysis; monoclinic, space group P21/a with a = 9.540(8), b = 9.977(3), c = 10.578(2)Å, β = 105.06(2)°. The B6 octahedron is compressed in the direction of the nearly linear B—CN bond by about 5%, with bond lengths between 1.71 and 1.76Å. The "B NMR spectra of the two compounds reveal the features of substituted B6 cages with C4v and C2v point symmetry. In the 13C NMR spectrum of Cs2[B6H5(CN)] a quartet at -139 ppm with 1J(C,B) 92 Hz is observed. The IR and Raman spectra exhibit very strong CN stretching bands for Cs2[B6H5(CN)] at 2149, and for cis-Cs2[B6H4(CN)2] at 2170 cm-1.

The evaluation and quantification of respirable coal and silica dust concentrations: a task-based approach

Silicosis and coal worker's pneumoconiosis are serious occupational respiratory diseases associated with the coal mining industry and the inhalation of respirable dusts containing crystalline silica. The purpose of this study (funded by the Mine Health and Safety Council of South Africa) was to evaluate the individual contributions of underground coal mining tasks to the respirable dust and respirable silica dust concentrations in an underground section by sampling the respirable dust concentrations at the intake and return of each task. The identified tasks were continuous miner (CM) cutting, construction, transfer of coal, tipping, and roof bolting. The respirable dust-generating hierarchy of the tasks from highest to lowest was: transfer of coal > CM right cutting > CM left cutting > CM face cutting > construction > roof bolting > tipping; and for respirable silica dust: CM left cutting > construction > transfer of coal > CM right cutting. Personal exposure levels were determined by sampling the exposures of workers performing tasks in the section. Respirable dust concentrations and low concentrations of respirable silica dust were found at the intake air side of the section, indicating that air entering the section is already contaminated. The hierarchy for personal respirable dust exposures was as follows, from highest to lowest: CM operator > cable handler > miner > roof bolt operator > shuttle car operator, and for respirable silica dust: shuttle car operator > CM operator > cable handler > roof bolt operator > miner. Dust control methods to lower exposures should include revision of the position of workers with regard to the task performed, positioning of the tasks with regard to the CM cutting, and proper use of the line curtains to direct ventilation appropriately. The correct use of respiratory protection should also be encouraged.

Two novel, putatively cell wall-associated and glycosylphosphatidylinositol-anchored alpha-glucanotransferase enzymes of Aspergillus niger

In the genome sequence of Aspergillus niger CBS 513.88, three genes were identified with high similarity to fungal alpha-amylases. The protein sequences derived from these genes were different in two ways from all described fungal alpha-amylases: they were predicted to be glycosylphosphatidylinositol anchored, and some highly conserved amino acids of enzymes in the alpha-amylase family were absent. We expressed two of these enzymes in a suitable A. niger strain and characterized the purified proteins. Both enzymes showed transglycosylation activity on donor substrates with alpha-(1,4)-glycosidic bonds and at least five anhydroglucose units. The enzymes, designated AgtA and AgtB, produced new alpha-(1,4)-glycosidic bonds and therefore belong to the group of the 4-alpha-glucanotransferases (EC 2.4.1.25). Their reaction products reached a degree of polymerization of at least 30. Maltose and larger maltooligosaccharides were the most efficient acceptor substrates, although AgtA also used small nigerooligosaccharides containing alpha-(1,3)-glycosidic bonds as acceptor substrate. An agtA knockout of A. niger showed an increased susceptibility towards the cell wall-disrupting compound calcofluor white, indicating a cell wall integrity defect in this strain. Homologues of AgtA and AgtB are present in other fungal species with alpha-glucans in their cell walls, but not in yeast species lacking cell wall alpha-glucan. Possible roles for these enzymes in the synthesis and/or maintenance of the fungal cell wall are discussed.

Branching mutants of Aspergillus oryzae with improved amylase and protease production on solid substrates

To study the relation between the number of hyphal tips and protein secretion during growth on a solid substrate, we have constructed two mutant strains of Aspergillus oryzae with increased hyphal branching. We have analysed hydrolytic enzyme activities during growth on wheat kernels (WK) of A. oryzae strains carrying the disrupted allele of the pclA gene encoding a secretion pathway specific (KEX2-like) endo-protease and the disrupted allele of the pg/pi-tp gene encoding a phosphatidylglycerol/phosphatidylinositol transfer protein. The biomass levels produced by the pclA and pg/pi-tp disrupted strains on wheat-based solid media were similar as found for the wild-type strain. However, the pclA disrupted strain showed much more compact colony morphology than the other two strains. Sporulation of the pclA and pg/pi-tp disrupted strains occurred, respectively, 2 days and 1 day later, compared to the wild type during fermentation on ground WK. During surface growth, microscopic analysis revealed that the hyphal growth unit length (L (hgu)) of the pclA and pg/pi-tp disrupted strains was, on average, 50 and 74% of that of the wild-type strain. This implies that in both mutant strains, a higher branching frequency occurs than in the wild-type strain. Compared to the wild-type strain, the pclA and pg/pi-tp disrupted strains produced at least 50% more amylase, at least 100% more glucoamylase and at least 90% more protease activity levels after growth on WK. These results support the hypothesis that branching mutants with an increased branching frequency can improve the solid state fermentation process.

Darstellung, 11 B-NMR- und Schwingungsspektren von cis-Dinitrotetrahydro-closo-hexaborat(2–), cis-[B6H4( NO2)2]2- sowie Kristallstruktur von cis-Cs2[B6H4(NO2)2] / Preparation, 11 B NMR and Vibrational Spectra of cis-Dinitrotetrahydro-closo-hexaborate(2–),cis-[B6H4(NO2)2]2-, and the Crystal Structure of cis-Cs2[B6H4(NO2)2]

By electrochemical oxidation of [B6H6,]2 in the presence of nitrite ions and of the base DBU in dichloromethane solution apart from [B6H5 (NO2)]2- and [B6H5(NO)B 6H5]3- the dinitro anion cis-[B6H4( NO2)2]2- is formed and can be isolated by ion exchange chromatography on diethylaminoethyl cellulose. The crystal structure of the Cs salt has been determined from single crystal X-ray diffraction analyses. cis-Cs2[B6H4 ( NO2)2] is tetragonal, space group P4̄21 m with a = 10.0656(4), c = 11.0127(13) Å. The 11B NMR spectrum is consistent with a disubstituted octahedral B6 cage with local C2v symmetry. The IR and Raman spectra exhibit characteristic NO2, B - H and B6 vibrations.

Darstellung, 11B-NMR- und Schwingungsspektren von Aminohexahydro-closo-hexaborat(1–), [B6H6(NH2)]- sowie Kristallstruktur von Cs[B6H6(NH2)] · H2O / Preparation, 11B NMR and Vibrational Spectra of Aminohexahydro-closo-hexaborate(1–), [B6H6(NH2)]-, and the Crystal Structure of Cs[B6H6(NH2)] · H2O

Aminohexahydro-closo-hexaborate(1–), Crystal Structure, 11B NMR Spectra, Vibrational Spectra

By reduction of [B6H5(NO2)]2- with Fe2+ in aqueous alkaline solution [B6H6(NH2)]- is formed. The compound has been separated by extraction with dichloromethane in the presence of tetrabutylammoniumbromid and precipitated from the organic phase by adding CsCH3COO/C2H5OH. The Crystal structure of Cs[B6H6(NH2)] · H2O has been determined by single crystal X-ray diffraction analysis; monoclinic space group C2 with a = 22.1075(14), b = 6.491(2), c = 5.9570(4) A, β = 100.168(6)°. The 11B NMR spectrum is consistent with a mono-hetero-substituted octahedral B6 cage with local C4v symmetry. The IR and Raman spectra exhibit characteristic N–H, B–H and B6 vibrations.