Clinimetric properties of relevant criteria for assessing writing and drawing orientation after right hemisphere stroke

BACKGROUND

Writing and drawing orientation is rarely assessed in clinical routine, although it might have a potential value in detecting impaired verticality perception after right hemispheric stroke (RHS). Assessment tools and criteria must be conceived and validated. We therefore explored the clinimetric properties of a set of quantitative writing and drawing orientation criteria, their ranges of normality, and their tilt prevalence in RHS individuals.

NEW METHODS

We asked 69 individuals with subacute RHS and 64 matched healthy controls to write three lines and to copy the Gainotti Figure (house and trees). We determined six criteria referring to the orientation of writing and drawing main axes: for writing, the line and margin orientations, and for drawing, the tree, groundline, wall, and roofline orientations. Orientations were measured by using an electronic protractor from specific landmarks positioned by independent evaluators.

RESULTS

The set of criteria fulfilling all clinimetric properties (feasibility, measurability, reliability) comprised the line orientation of the writing and the wall and roofline orientations of the drawing. Writing and drawing tilts were frequent after RHS (about 30% by criterion).

COMPARISON WITH EXISTING METHODS

So far, graphomotor orientation was mostly tested qualitatively and could not be objectively appreciated in absence of validated tools and criteria, and without ranges of normality. Writing and drawing tilts may now be assessed both in routine clinical practice and research.

CONCLUSIONS

Our study paves the way for investigating the clinical determinants of graphomotor tilts, including impaired verticality perception, to better understand their underlying mechanisms.

Identification of neutralising pembrolizumab anti-drug antibodies in patients with melanoma

Development of anti-drug antibodies (ADAs) can interfere with therapeutic monoclonal antibodies and may lead to drug neutralisation and clinical disease progression. Measurement of circulating drug levels and development of ADAs in the setting of anti-programmed cell death-1 agent pembrolizumab has not been well-studied. Enzyme-linked immunosorbent assays were used to measure pembrolizumab drug level and ADAs in 41 patients with melanoma at baseline, Time-point 1 (3 weeks) and Time-point 2 (21 weeks). Assay results were related to patient demographics and clinical outcome data at 6 months. The median pembrolizumab drug level at 3 weeks was 237 ng/μL and did not correlate with age, sex or body surface area.17/41 patients had an ADA detected at any timepoint, with the highest prevalence at Timepoint 1 (median concentration = 17 ng/μL). The presence of an ADA did not correlate with clinical progression at 6 months. 3/41 (7%) of patients displayed a falling pembrolizumab drug level and rising ADA titre between Timepoint 1 and 2 suggestive of a neutralising ADA. Pembrolizumab drug levels and ADAs can be readily measured. The rates of total and treatment-emergent ADAs may be higher in “real-word” settings than those previously reported. Larger studies are needed to determine effect of neutralising ADAs on long-term clinical outcome.

Characterizing genetic intra-tumor heterogeneity across 2,658 human cancer genomes

Intra-tumor heterogeneity (ITH) is a mechanism of therapeutic resistance and therefore an important clinical challenge. However, the extent, origin, and drivers of ITH across cancer types are poorly understood. To address this, we extensively characterize ITH across whole-genome sequences of 2,658 cancer samples spanning 38 cancer types. Nearly all informative samples (95.1%) contain evidence of distinct subclonal expansions with frequent branching relationships between subclones. We observe positive selection of subclonal driver mutations across most cancer types and identify cancer type-specific subclonal patterns of driver gene mutations, fusions, structural variants, and copy number alterations as well as dynamic changes in mutational processes between subclonal expansions. Our results underline the importance of ITH and its drivers in tumor evolution and provide a pan-cancer resource of comprehensively annotated subclonal events from whole-genome sequencing data.

Mucosal-associated invariant T (MAIT) cells are activated in the gastrointestinal tissue of patients with combination ipilimumab and nivolumab therapy-related colitis in a pathology distinct from ulcerative colitis

The aim of this study was to investigate the pathogenesis of combination ipilimumab and nivolumab-associated colitis (IN-COL) by measuring gut-derived and peripheral blood mononuclear cell (GMNC; PBMC) profiles. We studied GMNC and PBMC from patients with IN-COL, IN-treated with no adverse-events (IN-NAE), ulcerative colitis (UC) and healthy volunteers using flow cytometry. In the gastrointestinal-derived cells we found high levels of activated CD8⁺ T cells and mucosal-associated invariant T (MAIT) cells in IN-COL, changes that were not evident in IN-NAE or UC. UC, but not IN-C, was associated with a high proportion of regulatory T cells (T_reg ). We sought to determine if local tissue responses could be measured in peripheral blood. Peripherally, checkpoint inhibition instigated a rise in activated memory CD4⁺ and CD8⁺ T cells, regardless of colitis. Low circulating MAIT cells at baseline was associated with IN-COL patients compared with IN-NAE in one of two cohorts. UC, but not IN-COL, was associated with high levels of circulating plasmablasts. In summary, the alterations in T cell subsets measured in IN-COL-affected tissue, characterized by high levels of activated CD8⁺ T cells and MAIT cells and a low proportion of T_reg , reflected a pathology distinct from UC. These tissue changes differed from the periphery, where T cell activation was a widespread on-treatment effect, and circulating MAIT cell count was low but not reliably predictive of colitis.

Pan-cancer analysis of whole genomes

Cancer is driven by genetic change, and the advent of massively parallel sequencing has enabled systematic documentation of this variation at the whole-genome scale1-3. Here we report the integrative analysis of 2,658 whole-cancer genomes and their matching normal tissues across 38 tumour types from the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium of the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA). We describe the generation of the PCAWG resource, facilitated by international data sharing using compute clouds. On average, cancer genomes contained 4-5 driver mutations when combining coding and non-coding genomic elements; however, in around 5% of cases no drivers were identified, suggesting that cancer driver discovery is not yet complete. Chromothripsis, in which many clustered structural variants arise in a single catastrophic event, is frequently an early event in tumour evolution; in acral melanoma, for example, these events precede most somatic point mutations and affect several cancer-associated genes simultaneously. Cancers with abnormal telomere maintenance often originate from tissues with low replicative activity and show several mechanisms of preventing telomere attrition to critical levels. Common and rare germline variants affect patterns of somatic mutation, including point mutations, structural variants and somatic retrotransposition. A collection of papers from the PCAWG Consortium describes non-coding mutations that drive cancer beyond those in the TERT promoter4; identifies new signatures of mutational processes that cause base substitutions, small insertions and deletions and structural variation5,6; analyses timings and patterns of tumour evolution7; describes the diverse transcriptional consequences of somatic mutation on splicing, expression levels, fusion genes and promoter activity8,9; and evaluates a range of more-specialized features of cancer genomes8,10-18.

The evolutionary history of 2,658 cancers

Cancer develops through a process of somatic evolution1,2. Sequencing data from a single biopsy represent a snapshot of this process that can reveal the timing of specific genomic aberrations and the changing influence of mutational processes3. Here, by whole-genome sequencing analysis of 2,658 cancers as part of the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium of the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA)4, we reconstruct the life history and evolution of mutational processes and driver mutation sequences of 38 types of cancer. Early oncogenesis is characterized by mutations in a constrained set of driver genes, and specific copy number gains, such as trisomy 7 in glioblastoma and isochromosome 17q in medulloblastoma. The mutational spectrum changes significantly throughout tumour evolution in 40% of samples. A nearly fourfold diversification of driver genes and increased genomic instability are features of later stages. Copy number alterations often occur in mitotic crises, and lead to simultaneous gains of chromosomal segments. Timing analyses suggest that driver mutations often precede diagnosis by many years, if not decades. Together, these results determine the evolutionary trajectories of cancer, and highlight opportunities for early cancer detection.

Timing somatic events in the evolution of cancer

Cancer arises through the accumulation of somatic mutations over time. An understanding of the sequence of events during this process should allow both earlier diagnosis and better prediction of cancer progression. However, the pathways of tumor evolution have not yet been comprehensively characterized. With the advent of whole genome sequencing, it is now possible to infer the evolutionary history of single tumors from the snapshot of their genome taken at diagnosis, giving new insights into the biology of tumorigenesis.

Abstract 218: The evolutionary history of 2,658 cancers

Cancer develops through a continuous process of somatic evolution. Whole genome sequencing provides a snapshot of the tumor genome at the point of sampling, however, the data can contain information that permits the reconstruction of a tumor's evolutionary past.

Here, we apply such life history analyses on an unprecedented scale, to a set of 2,658 tumors spanning 39 cancer types. We estimated the timing of large chromosomal gains during tumor evolution, by comparing the rates of doubled to non-doubled point mutations within gained regions. Although we find that such events typically occur in the second half of clonal evolution, we also observe distinctive and early chromosomal gains in some cancer types, such as gains of chromosomes 7, 19 and 20 in glioblastoma, and isochromosome 17q in medulloblastoma. By integrating these results with the qualitative timing of individual driver mutations, we obtained an overall ranking, from early to late, of frequent somatic events per cancer type, which both identified novel patterns of tumor evolution, and incorporated additional detail into known models, such as the progression of APC-KRAS-TP53 in colorectal cancer proposed by Vogelstein and Fearon.

To estimate how mutational processes acting on the tumor genome change over time, we classified mutations in each sample according to three broad time periods (early clonal, late clonal, and subclonal), and quantified the activity of mutational signatures in each period. Most mutational processes appear to remain remarkably constant, however, certain signatures show clear and consistent changes during clonal evolution. Particularly, mutational signatures associated with exposure to carcinogens, such as smoking and UV light, tend to decrease over time. In contrast, signatures associated with defective endogenous processes, such as APOBEC mutagenesis and defective double strand break repair, show an increase between early and late phases of tumor evolution.

Making use of clock-like mutational signatures, we converted mutational time estimates for large events, such as whole genome duplication (WGD), and the emergence of the most recent common ancestor (MRCA), into real time estimates, which allowed us to combine our analyses into overall timelines of cancer evolution, per tumor type. For example, the typical timeline of ovarian adenocarcinoma development shows that early tumor evolution is characterized by mutations in TP53, and widespread genome instability, with WGD events taking place on average 8 years prior to diagnosis. In later stages of evolution, signatures of defective repair processes increase, and the MRCA emerges on average 1 year before diagnosis.

Taken together, these data reveal the common and divergent evolutionary trajectories available to a cancer, which might be crucial in understanding specific tumor biology, and in providing new opportunities for early detection and cancer prevention.

Citation Format: Clemency Jolly, Moritz Gerstung, Ignaty Leshchiner, Stefan C. Dentro, Santiago Gonzalez, Thomas J. Mitchell, Yulia Rubanova, Pavana Anur, Daniel Rosebrock, Kaixian Yu, Maxime Tarabichi, Amit Deshwar, Jeff Wintersinger, Kortine Kleinheinz, Ignacio Vásquez-García, Kerstin Haase, Subhajit Sengupta, Geoff Macintyre, Salem Malikic, Nilgun Donmez, Dimitri G. Livitz, Mark Cmero, Jonas Demeulemeester, Steve Schumacher, Yu Fan, Xiaotong Yao, Juhee Lee, Matthias Schlesner, Paul C. Boutros, David D. Bowtell, Hongtu Zhu, Gad Getz, Marcin Imielinski, Rameen Beroukhim, S Cenk Sahinalp, Yuan Ji, Martin Peifer, Florian Markowetz, Ville Mustonen, Ke Juan, Wenyi Wang, Quaid D. Morris, Paul T. Spellman, David C. Wedge, Peter Van Loo, PCAWG Evolution and Heterogeneity Working Group. The evolutionary history of 2,658 cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 218.

Abstract P3-07-10: Modulation of FASN under obese conditions

Introduction: Obesity is known to be associated with a worse breast cancer prognosis, in part through altering metabolism in cells of the tumor microenvironment. In particular, changes in metabolism associated with fatty acid utilization have been noted in not only breast cancer, but also several other cancer types. This includes changes to both expression and activity of the Fatty Acid Synthase enzyme (FASN), which is responsible for production of long chain fatty acids, including palmitate. These changes in long chain fatty acid production can modulate tumor behavior through modulation of energy utilization such as beta-oxidation, as well as plasma membrane modulation with phospholipids. Our previous studies have demonstrated that exposure to obese conditions induces significant changes in breast cancer cell proliferation. Additionally, obesity modulates activity of other cells within the tumor microenvironment, including adipocytes, which might influence the cancer cell itself. We hypothesize one particular mechanism that supports these changes is obesity-induced upregulation of FASN and that FASN may be a viable target to limit obesity-induced progression.

Methods and Results: FASN has been shown to promote cancer cell proliferation through generating fatty acid precursors required for cell proliferation, altering membrane fluidity, and activating oncogenic signaling pathways. To determine if modulation of FASN is an important mechanism by which obesity promotes disease progression, MCF-7 breast cancer cells and human pre-adipocyte cells (ASC) were exposed to 2% sera from obese postmenopausal women and 2% sera from non-obese (control) women. Preliminary quantitative PCR results demonstrated that exposure to the obese sera resulted in increased expression of FASN in both the cancer cells as well as the ASC. Current studies are on-going to determine if 1) FASN up-regulation results in increased long-chain and free fatty acid production in both the cancer and adipocyte cells, 2) whether changes in long chain and free fatty acid production results in altered metabolism and plasma membrane status and 3) whether targeting FASN with a new generation of FASN inhibitors currently being investigated in the clinic can modulate obesity-induced disease progression.

Conclusions: Our findings indicate that obesity promotes upregulation of FASN in several cells within the tumor microenvironment, including adipocytes and the cancer cell itself. We have also found that using a FASN inhibitor is effective in limiting cancer cell viability and proliferation. Our on-going studies will confirm if this is an important mechanism by which obesity promotes disease progression. Since FASN inhibitors are currently being investigated in the clinic, the results of these studies will provide a better understanding of how obesity alters the biology of the disease, and may identify a novel target for improving patient outcomes.

Citation Format: Pham T, Oberman A, Kim I, Lee G, Quach D, Galván G, Jolly C, Cavazos D, Brenner A, deGraffenried L. Modulation of FASN under obese conditions [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P3-07-10.

Abstract P6-17-03: The importance of the ultimate ratio of Omega-6 to Omega-3 fatty acids in the efficacy of fish oil supplements in suppressing inflammation in obese postmenopausal women

Over the last decade, a large body of evidence has established that obesity is associated with a worse breast cancer prognosis for both pre- and postmenopausal women. There are several mechanisms which have been proposed for promoting this effect, including stage of diagnosis and co-morbidities, but more recent evidence suggests that the obese state is associated with changes in the biology of the disease, promoting a more aggressive phenotype. Our recently published in vitro and retrospective studies suggest that this is due, at least in part, through cyclooxygenase 2 (COX-2)-derived prostaglandin E2 (PGE2), and that interventions that suppress COX-2 PGE2 production may provide significant benefit for the obese ER+ patient in preventing many of the cancer-promoting effects associated with obesity. Omega-3 fatty acids have demonstrated anti-cancer benefit through multiple mechanisms, including suppression of inflammation-related signaling. DHA and EPA (omega-3 PUFAs found in fish oil) modulate inflammatory responses through COX-2 dependent and independent mechanisms. However, previous studies investigating the potential anti-cancer benefit of omega-3 PUFA and fish oil supplementation have produced mixed results, and none have focused specifically on the obese patient population.

To determine if supplementation with non-steroidal anti-inflammatory drugs (NSAIDs), including omega-3 fatty acids, can effectively suppress PGE2 production in the obese postmenopausal patient, we conducted a double-blind, prospective Phase 0, comparative, 30 day, non-interventional study with correlative biomarker endpoints. One hundred twenty (120) postmenopausal women without breast cancer were randomized to three arms 1. ASA 81mg po daily, 2. 1500mg of docosahexaoic acid (DHA) and 2500mg eicosapentanoic acid (EPA) given daily and 3. Combined ASA and DHA/EPA at above doses. Serum samples were collected prior to and on day 29 of taking the supplements. PGE2 levels in the pre- and post-supplement serum samples were analyzed in triplicate by ELISA and presented as the percentage of change between post- and pre-supplement levels. Of the women in Arm 2 (DHA + EPA only), only 55% demonstrated a significant suppression of PGE2 levels after 30 day of supplements, compared to those in Arm 1 (ASA), in which 80% demonstrated a significant response.

We anticipate that the omega-3 fatty acid supplements were not as effective in as large a population as the aspirin due to a failure to reach a critical ratio between circulating levels omega-6 and omega-3 fatty acids, which has been shown by our own group and others to be a key determinant of cellular response. Studies are on-going to analyze the PUFA levels in both the pre and post supplement serum samples, and pre-clinical studies are being conducted to determine if the ratio of omega-6 to omega-3 PUFAs modulates PGE2 production in several different cell types, including macrophages, adipocytes and the breast cell itself. These results will be critical for moving clinical studies utilizing these agents forward, both in terms of elucidating the mechanism mediating an effect, and also in identifying an accurate biomarker for monitoring compliance and response.

Citation Format: Quach D, Lengfelder L, Winnika L, Harlow B, Galvan G, Jolly C, Brenner A, deGraffenried L. The importance of the ultimate ratio of Omega-6 to Omega-3 fatty acids in the efficacy of fish oil supplements in suppressing inflammation in obese postmenopausal women [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P6-17-03.

Transient structural variations have strong effects on quantitative traits and reproductive isolation in fission yeast

Large structural variations (SVs) within genomes are more challenging to identify than smaller genetic variants but may substantially contribute to phenotypic diversity and evolution. We analyse the effects of SVs on gene expression, quantitative traits and intrinsic reproductive isolation in the yeast Schizosaccharomyces pombe. We establish a high-quality curated catalogue of SVs in the genomes of a worldwide library of S. pombe strains, including duplications, deletions, inversions and translocations. We show that copy number variants (CNVs) show a variety of genetic signals consistent with rapid turnover. These transient CNVs produce stoichiometric effects on gene expression both within and outside the duplicated regions. CNVs make substantial contributions to quantitative traits, most notably intracellular amino acid concentrations, growth under stress and sugar utilization in winemaking, whereas rearrangements are strongly associated with reproductive isolation. Collectively, these findings have broad implications for evolution and for our understanding of quantitative traits including complex human diseases.

Functional Characterisation of Eel Dopamine D2 Receptors and Involvement in the Direct Inhibition of Pituitary Gonadotrophins

In various vertebrate species, dopamine (DA) exerts an inhibitory action on reproduction. In the European eel, DA plays a pivotal role in the inhibitory control of gonadotroph function and the blockade of puberty. In vivo studies have suggested that this effect is mediated by receptors pharmacologically related to the D2 family. In the European eel, two distinct D2 receptor (D2-R) paralogous genes have been identified (D2A-R and D2B-R) and both were shown to be expressed in the pituitary. We investigated the potential role of each paralogue in the control of gonadotroph function in this species. Eel recombinant D2A-R or D2B-R were expressed in HEK 293 cells, with a universal Gα subunit, and receptor activation was followed by inositol phosphate production. Recombinant D2-Rs exhibited a comparable affinity for DA, although they had differential affinities for mammalian D2-R agonists and antagonists, supporting subtle structure/activity differences. Furthermore, using eel pituitary cell primary cultures, the expression by gonadotroph cells of both native eel D2-R paralogues was examined by in situ hybridisation of D2A-R or D2B-R transcripts, coupled with immunofluorescence of luteinising hormone (LH)β or follicle-stimulating (FSH)β. LH and to a lesser extent, FSH cells expressed both D2-R transcripts but with a clear predominance of D2B-R. Notably, D2B-R transcripts were detected for the majority of LH cells. Accordingly, using these cultures, we showed that DA potently inhibited basal and testosterone-stimulated LHβ expression and less potently basal and activin-stimulated FSHβ expression. We also tested some D2-R antagonists, aiming to select the most adequate one to be used in innovative protocols for induction of eel sexual maturation. We identified eticlopride as the most potent inhibitor of DA action on basal and stimulated LH expression in vitro. Our data suggest a differential functionalisation of the duplicated receptor genes and demonstrate that mainly D2B-R is involved in the dopaminergic inhibitory control of eel gonadotroph function.

Anti-androgens act jointly in suppressing spiggin concentrations in androgen-primed female three-spined sticklebacks - prediction of combined effects by concentration addition

Increasing attention is being directed at the role played by anti-androgenic chemicals in endocrine disruption of wildlife within the aquatic environment. The co-occurrence of multiple contaminants with anti-androgenic activity highlights a need for the predictive assessment of combined effects, but information about anti-androgen mixture effects on wildlife is lacking. This study evaluated the suitability of the androgenised female stickleback screen (AFSS), in which inhibition of androgen-induced spiggin production provides a quantitative assessment of anti-androgenic activity, for predicting the effect of a four component mixture of anti-androgens. The anti-androgenic activity of four known anti-androgens (vinclozolin, fenitrothion, flutamide, linuron) was evaluated from individual concentration-response data and used to design a mixture containing each chemical at equipotent concentrations. Across a 100-fold concentration range, a concentration addition approach was used to predict the response of fish to the mixture. Two studies were conducted independently at each of two laboratories. By using a novel method to adjust for differences between nominal and measured concentrations, good agreement was obtained between the actual outcome of the mixture exposure and the predicted outcome. This demonstrated for the first time that androgen receptor antagonists act in concert in an additive fashion in fish and that existing mixture methodology is effective in predicting the outcome, based on concentration-response data for individual chemicals. The sensitivity range of the AFSS assay lies within the range of anti-androgenicity reported in rivers across many locations internationally. The approach taken in our study lays the foundations for understanding how androgen receptor antagonists work together in fish and is essential in informing risk assessment methods for complex anti-androgenic mixtures in the aquatic environment.

Use of cutaneous flap for continent cystostomy (daoud technique)

PURPOSE

We present the results of a new technique using a pedicled cutaneous flap for continent cystostomy.

MATERIALS AND METHODS

A total of 15 boys and 8 girls (mean +/- SD age 13.4 +/- 6.4 years) underwent continent cystostomy for neurogenic bladder (20), bladder exstrophy (2) and sequelae of hypospadias (1) between 1999 and 2008. In this procedure a rectangular pedicled flap is surgically elevated from a hairless area on the abdomen. The flap is tubularized and passed through the anterior abdominal wall directly into the bladder. A submucosal detrusor incision is made to expose the bladder mucosa, and the distal part of the flap is anastomosed to the bladder mucosa in a circular manner. The tube is positioned along the incised detrusor, which is closed over. Viability of the flap, self-catheterization management and continence status are then evaluated.

RESULTS

Mean +/- SD followup was 4.5 +/- 3.1 years. There was 1 case of distal necrosis of the flap, which required a secondary surgery using the Mitrofanoff technique. The 22 remaining flaps were initially viable, although 2 patients were eventually lost to followup and 3 subsequently presented with false-passage incidents requiring a few days of calibration using a balloon catheter. Dryness was achieved immediately in 73% of the cases. After adding a complementary bulking agent the dryness rate reached 77%.

CONCLUSIONS

We present a novel approach to continent cystostomy that is safe and easy to perform. This technique is a less invasive and more efficient alternative to other commonly used approaches.

Electrode features for hearing preservation and drug delivery strategies

BACKGROUND/AIMS

Reducing the risk of hearing loss after cochlear implantation requires optimization of the electrode array to minimize the physical trauma caused by insertion and placement. Furthermore, the electrode design must be optimized for atraumatic surgical approaches. Even greater levels of protection may be achieved by the use of a drug during and after implantation. The electrode array offers a potential vehicle for drug delivery.

METHODS

This article reviews the laboratory and clinical data available thus far relating to the importance of electrode design parameters for trauma minimization, and the possibility of further reduction through pharmaceutical intervention. Candidate drugs were identified through literature review and laboratory evaluation. The most promising have been investigated in vitro and in animal models of implantation trauma. Three delivery devices are currently under development to satisfy the specific demands of different therapy regimes. The delivery profiles of each were evaluated through both modelling and bench testing and the concepts investigated in vitro and in vivo.

RESULTS

Current evidence favours a thin, flexible electrode array with wires in a zigzag shape. Steroids and an apoptosis inhibitor (AM111) performed well in animal models of electrode trauma and are both good drug candidates for reduction of the risk of hearing loss after implantation. Semi-chronic dexamethasone elution, acute drug delivery by intracochlear catheter, and longer-term delivery through diffusion from a reservoir were all shown to be feasible.

CONCLUSION

An extensive programme focussed on minimizing hearing loss through device optimization and the development of new technologies has yielded positive results and new concepts for further development and clinical application.

Measuring bidirectional mutation

The estimation of mutation rates is usually based on a model in which mutations are rare independent Poisson events. Back-mutation of mutants, an even rarer event, is ignored. In the hypermutating B cells of the immune system, mutation between phenotypes exhibiting, vs. not exhibiting, surface immunoglobulin is common in both directions. We develop three strategies for the estimation of mutation rates under circumstances such as these, where mutation rates in both directions are estimated simultaneously. Our model for the growth of a cell culture departs from the classical assumption of cell division as a memoryless (Poisson) event; we model cell division as giving rise to sequential generations of cells. On this basis, a Monte-Carlo simulation is developed. We develop also a numerical approach to calculating the probability distribution for the proportion of mutants in each culture as a function of forward- and backward-mutation rates. Although both approaches are too computationally intensive for routine laboratory use, they provide the insight necessary to develop and evaluate a third, 'hand-calculator' approach to extracting mutation rate estimators from experiments of this type.

The use of a decremental dose regimen in patients treated with a chronic low-dose step-up protocol for WHO Group II anovulation: a prospective randomized multicentre study

BACKGROUND

In women with chronic anovulation, the choice of the FSH starting dose and the modality of subsequent dose adjustments are critical in controlling the risk of overstimulation. The aim of this prospective randomized study was to assess the efficacy and safety of a decremental FSH dose regimen applied once the leading follicle was 10-13 mm in diameter in women treated for WHO Group II anovulation according to a chronic low-dose (CLD; 75 IU FSH for 14 days with 37.5 IU increment) step-up protocol.

METHODS

Two hundred and nine subfertile women were treated with recombinant human FSH (r-hFSH) (Gonal-f) for ovulation induction according to a CLD step-up regimen. When the leading follicle reached a diameter of 10-13 mm, 158 participants were randomized by means of a computer-generated list to receive either the same FSH dose required to achieve the threshold for follicular development (CLD regimen) or half of this FSH dose [sequential (SQ) regimen]. HCG was administered only if not more than three follicles >or=16 mm in diameter were present and/or serum estradiol (E(2)) values were <1200 pg/ml. The primary outcome measure was the number of follicles >or=16 mm in size at the time of hCG administration.

RESULTS

Clinical characteristics and ovarian parameters at the time of randomization were similar in the two groups. Both CLD and SQ protocols achieved similar follicular growth as regards the total number of follicles and medium-sized or mature follicles (>/=16 mm: 1.5 +/- 0.9 versus 1.4 +/- 0.7, respectively). Furthermore, serum E(2) levels were equivalent in the two groups at the time of hCG administration (441 +/- 360 versus 425 +/- 480 pg/ml for CLD and SQ protocols, respectively). The rate of mono-follicular development was identical as well as the percentage of patients who ovulated and achieved pregnancy.

CONCLUSIONS

The results show that the CLD step-up regimen for FSH administration is efficacious and safe for promoting mono-follicular ovulation in women with WHO Group II anovulation. This study confirms that maintaining the same FSH starting dose for 14 days before increasing the dose in step-up regimen is critical to adequately control the risk of over-response. Strict application of CLD regimen should be recommended in women with WHO Group II anovulation.

High-resolution ultrasonography of subretinal structure and assessment of retina degeneration in rat

The purpose of this work was to evaluate the ability of 80 MHz ultrasonography to differentiate intra-retinal layers and quantitatively assess photoreceptor dystrophy in small animal models. Four groups of 10 RCS rats each (five dystrophic and five controls) were explored at 25, 35, 45 and 55 days post-natal (PN). A series of retina cross-sections were obtained ex vivo from outside intact eyes using an 80 MHz three-dimensional ultrasound backscatter microscope (20-microm-axial resolution). Ultrasound features of normal retina were correlated to those of corresponding histology and thickness measurements of photoreceptor segment and nuclear layers were performed on all groups. To show the ability of 80 MHz ultrasonography to distinguish the retinal degeneration in vivo, one RCS rat was explored at 25 and 55 days post-natal. Ultrasound image of normal retina displayed four distinct layers marked by reflections at neurites/nuclei interfaces and permitted to differentiate the photoreceptor segment and nuclear layers. The backscatter level from the retina was shown to be related to the size, density and organization of the intra-layer structure. Ultrasound thickness measurements highly correlated with histologic measurements. A thinning (p<0.05) of outer nuclear layer (ONL) was detected over time for controls and was thought to be assigned to retina maturation. Retinal degeneration started at PN35 and resulted in a more pronounced ONL thinning (p<0.05) over time. ONL degeneration was accompanied by segment layer thickening (p<0.05) at PN35 and thinning thereafter. These changes may indicate accumulation of outer segment debris at PN35 then progressive destruction. In vivo images of rat intra-retinal structure showed the ability of the method to distinguish the photoreceptor layer changes. Our results indicate that 80 MHz ultrasonography reveals intra-retinal layers and is sensitive to age and degenerative changes of photoreceptors. This technique has great potential to follow-up retinal dystrophy and therapeutic effects in vivo.

Movements of cochlear implant electrodes inside the cochlea during insertion: an x-ray microscopy study

BACKGROUND

There are no satisfactory, noninvasive techniques currently available to visualize the cochlear implant (CI) electrode in a dynamic state as it is advanced inside the cochlea.

OBJECTIVE

This study describes a radiologic technique that can be used in temporal bones to monitor the electrode position in real time and to visualize the basilar membrane.

METHODS

A cochleostomy was performed in accordance with the normal procedure for cochlear implantation in seven fresh cadaveric temporal bones. A special x-ray tube (Microfocus; Focus, Wunstorf, Germany) with a spot size of 1 microm and fluoroscopy were used for continuous videotape imaging of the advancing electrode in the cochlea. Conventional electrodes (MED-EL 40+; MED-EL, Innsbruck, Austria) and prototypes of perimodiolar electrodes (MED-EL), with varying thicknesses and angles of insertion, were used for the study. Finally, contrast liquid (Ultravist; Berlex Imaging, Schering, Germany) was injected into the scala vestibuli through the stapes footplate.

RESULTS

The advancing electrode carrier was clearly visible at x20 magnification. With the perimodiolar electrodes, deep insertion was impossible if the guiding wire was too rigid, and retraction occurred if the wire was soft. The intact nature of the basilar membrane could be confirmed by the sequential filling of scala vestibuli and the scala tympani.

CONCLUSION

To our knowledge, this is the first noninvasive study demonstrating continuous visualization with high-resolution and x-ray magnification of CI electrode advancement inside the intact cochlea. Our technique can be used for the development of CI electrodes with optimal design characteristics, especially stiffness. Visualization of the basilar membrane will influence the insertion techniques when CIs are developed for patients with residual hearing.

Insights into the catalytic mechanism of HlyC, the internal protein acyltransferase that activates Escherichia coli hemolysin toxin

Hemolysin, a toxic protein secreted by pathogenic Escherichia coli, is converted from nontoxic prohemolysin, proHlyA, to toxic hemolysin, HlyA, by an internal protein acyltransferase, HlyC. Acyl-acyl carrier protein (ACP) is the essential acyl donor. The acyltransferase reaction proceeds through two partial reactions and entails formation of a reactive acyl-HlyC intermediate [Trent, M. S., Worsham, L. M., and Ernst-Fonberg, M. L. (1999) Biochemistry 38, 9541-9548]. The ping pong kinetic mechanism implied by these findings was validated using two different acyl-ACP substrates, thus verifying the independence of the previously demonstrated two partial reactions. Assessments of the stability of the acyl-HlyC intermediate revealed an increased stability at pH 8.6 compared to more acidic pHs. Mutations of a single conserved histidine residue essential for catalysis gave minimal activity when substituted with a tyrosine residue and no activity with a lysine residue. Unlike numerous other His23 mutants, however, the H23K enzyme showed significant acyl-HlyC formation although it was unable to transfer the acyl group from the proposed amide bond intermediate to proHlyA. These findings are compatible with transient formation of acyl-His23 during the course of HlyC catalysis. The effects of several other single site-directed mutations of conserved residues of HlyC on different portions of the reaction progress were examined using a 39 500 kDa fragment of proHlyA which was a more effective substrate than intact proHlyA.

Stress-specific activation and repression of heat shock factors 1 and 2

Vertebrate cells express a family of heat shock transcription factors (HSF1 to HSF4) that coordinate the inducible regulation of heat shock genes in response to diverse signals. HSF1 is potent and activated rapidly though transiently by heat shock, whereas HSF2 is a less active transcriptional regulator but can retain its DNA binding properties for extended periods. Consequently, the differential activation of HSF1 and HSF2 by various stresses may be critical for cells to survive repeated and diverse stress challenges and to provide a mechanism for more precise regulation of heat shock gene expression. Here we show, using a novel DNA binding and detection assay, that HSF1 and HSF2 are coactivated to different levels in response to a range of conditions that cause cell stress. Above a low basal activity of both HSFs, heat shock preferentially activates HSF1, whereas the amino acid analogue azetidine or the proteasome inhibitor MG132 coactivates both HSFs to different levels and hemin preferentially induces HSF2. Unexpectedly, we also found that heat shock has dramatic adverse effects on HSF2 that lead to its reversible inactivation coincident with relocalization from the nucleus. The reversible inactivation of HSF2 is specific to heat shock and does not occur with other stressors or in cells expressing high levels of heat shock proteins. These results reveal that HSF2 activity is negatively regulated by heat and suggest a role for heat shock proteins in the positive regulation of HSF2.

Synthesis and biological evaluation of sialylmimetics as rotavirus inhibitors

Rotaviruses cause severe gastroenteritis in infants and are estimated to be responsible for over 600 000 deaths annually, primarily in developing countries. The development of potential inhibitors of this virus is therefore of great interest, particularly since the safety and efficacy of rotaviral vaccines has recently been questioned. This study describes the synthesis of a variety of compounds that can be considered as mimetics of N-acetylneuraminic acid thioglycosides and the subsequent in vitro biological evaluation of these sialylmimetics as inhibitors of rotaviral infection. Our results show that readily accessible carbohydrate-based compounds have the potential to act as inhibitors of rotaviral replication in vitro, presumably through inhibition of the rotaviral adhesion process.

[Visualization of cochlear implant electrode movements in the cochlea by using x-ray microscopy]

BACKGROUND

The movements of the electrode cable of a cochlear implant inside the cochlea during the insertion procedure generally are invisible, even in temporal bone experiments. Yet, the development of new designs of electrodes, their positioning near to the modiolus etc. requires an exact knowledge on the dynamic behaviour of the electrodes inside the cochlea. The exclusive method for looking through the undamaged cochlea walls is by x-ray technique.

METHODS

A specific x-ray tube with a focal spot size of barely 5 microns allows useful direct magnifications of more than 20-30 times. We performed temporal bone experiments with this tube and studied the behaviour of conventional and perimodiolar electrode cables of a MedEl-Cl during the insertion procedure under fluoroscopic viewing.

RESULTS

The high resolution imaging revealed the influence of stiffness of the electrode cable on the insertion depth of a conventional electrode. If the angle of the direction of insertion was too steep, the resulting kinking of the cable at the medial wall of the basal turn was instantly visible. The direct visualisation of the movements of the cable was useful in optimizing the design and stiffness of various prototypes of perimodiolar electrodes for a deep insertion.

CONCLUSIONS

The dynamic examination technique disclosed that the stiffness of actual electrode cables is not optimally adapted to the form of the cochlear cavity for deep insertion. The non-destructive visualisation technique will facilitate the development of advanced electrode design, especially for various concepts of perimodiolar electrodes.

Role of the heat shock response and molecular chaperones in oncogenesis and cell death

Exposure of cells to conditions of environmental stress-including heat shock, oxidative stress, heavy metals, or pathologic conditions, such as ischemia and reperfusion, inflammation, tissue damage, infection, and mutant proteins associated with genetic diseases-results in the inducible expression of heat shock proteins that function as molecular chaperones or proteases. Molecular chaperones are a class of proteins that interact with diverse protein substrates to assist in their folding, with a critical role during cell stress to prevent the appearance of folding intermediates that lead to misfolded or otherwise damaged molecules. Consequently, heat shock proteins assist in the recovery from stress either by repairing damaged proteins (protein refolding) or by degrading them, thus restoring protein homeostasis and promoting cell survival. The events of cell stress and cell death are linked, such that molecular chaperones induced in response to stress appear to function at key regulatory points in the control of apoptosis. On the basis of these observations-and on the role of molecular chaperones in the regulation of steroid aporeceptors, kinases, caspases, and other protein remodeling events involved in chromosome replication and changes in cell structure-it is not surprising that the heat shock response and molecular chaperones have been implicated in the control of cell growth. In this review, we address some of the molecular and cellular events initiated by cell stress-the interrelationships between stress signaling, cell death, and oncogenesis-and chaperones as potential targets for cancer diagnosis and treatment.

Intron-independent association of splicing factors with active genes

The cell nucleus is organized as discrete domains, often associated with specific events involved in chromosome organization, replication, and gene expression. We have examined the spatial and functional relationship between the sites of heat shock gene transcription and the speckles enriched in splicing factors in primary human fibroblasts by combining immunofluorescence and fluorescence in situ hybridization (FISH). The hsp90alpha and hsp70 genes are inducibly regulated by exposure to stress from a low basal level to a high rate of transcription; additionally the hsp90alpha gene contains 10 introns whereas the hsp70 gene is intronless. At 37 degrees C, only 30% of hsp90alpha transcription sites are associated with speckles whereas little association is detected with the hsp70 gene, whose constitutive expression is undetectable relative to the hsp90alpha gene. Upon exposure of cells to heat shock, the heavy metal cadmium, or the amino acid analogue azetidine, transcription at the hsp90alpha and hsp70 gene loci is strongly induced, and both hsp transcription sites become associated with speckles in >90% of the cells. These results reveal a clear disconnection between the presence of intervening sequences at specific gene loci and the association with splicing factor-rich regions and suggest that subnuclear structures containing splicing factors are associated with sites of transcription.

Rapid and reversible relocalization of heat shock factor 1 within seconds to nuclear stress granules

Heat shock factor 1 (HSF1) is essential for the stress-induced expression of heat shock genes. On exposure to heat shock, HSF1 localizes within seconds to discrete nuclear granules. On recovery from heat shock, HSF1 rapidly dissipates from these stress granules to a diffuse nucleoplasmic distribution, typical of unstressed cells. Subsequent reexposure to heat shock results in the rapid relocalization of HSF1 to the same stress granules with identical kinetics. Although the appearance of HSF1 stress granules corresponds to the hyperphosphorylated, trimeric DNA-binding state of HSF1 and correlates temporally with the inducible transcription of heat shock genes, they are also present in heat-shocked mitotic cells that are devoid of transcription. This finding suggests a role for HSF1 stress granules as a nuclear compartment for the temporal regulation and spatial organization of HSF1 activity and reveals new features of the dynamics of nuclear organization.

Genomic structure and chromosomal mapping of the mouse STOP gene (Mtap6)

The microtubule associated protein STOP (Stable Tubule Only Polypeptide) is a calmodulin-regulated protein able to induce a high degree of microtubule stability. STOP is abundant in neurons which contain large subpopulations of stable microtubules. Genomic clones spanning 67 kb and encompassing the mouse STOP gene (Mtap6) have been isolated and characterized. These clones derive from a single gene mapping to the E2-F1 region of mouse chromosome 7. The gene is composed of 4 exons that exhibit conventional vertebrate splicing sequences. Transcription of the gene initiate at multiple sites in a 85 nucleotide region located 530 bases upstream the translation initiation codon. Accordingly, the 5' flanking region of the gene lacks a TATA box or an initiator element at usual position. The protein encoded by the mouse STOP gene (Mtap6) is composed of 906 amino acids and presents a 91% identities with the rat brain STOP.

Contribution of growing RNA molecules to the nuclear transcripts foci observed by FISH

The focal distributions of RNAs observed using fluorescence in situ hybridization (FISH) in the cell nucleus may correspond either to RNAs in the course of transcription or essentially to accumulation of full-length transcripts at the sites of transcription. To determine to what extent nuclear transcript foci represent growing RNA molecules, uninterrupted hsp70 transcripts were detected by FISH in heat-shocked human fibroblasts using two probes specific for the 5' or for the 3' end of the transcripts. By comparing the size of the signals obtained with each probe, we show that transcript foci mainly represent accumulations of full-length transcripts at their site of transcription. A major contribution of RNAs in the course of transcription to the transcript foci is observed only during the first minutes of gene induction. These observations suggest the existence of a rate-limiting step in the release of newly synthesized transcripts from their site of transcription, which is independent from the step of intron excision.

Optimization of nuclear transcript detection by FISH and combination with fluorescence immunocytochemical detection of transcription factors

Detection of specific nuclear transcripts by fluorescence in situ hybridization (FISH) has constituted a major breakthrough in the study of the organization of transcription in the cell nucleus. Using the model of heat shock genes, we present an optimized procedure for nuclear transcripts that provides high efficiency for RNA detection and good preservation of cell morphology and nuclear texture. Using this procedure, we designed an original high-efficiency methodology combining FISH and fluorescence immunocytochemistry (FICC), which is used here for the simultaneous detection of heat-shock protein (hsp) nuclear transcripts and the specific heat-shock transcription factor 1 (HSF1). We show that the nuclear accumulation sites of HSF1 in heat-shocked cells do not correspond to the sites of transcription of the hsp70 gene.

HSF1 transcription factor concentrates in nuclear foci during heat shock: relationship with transcription sites

In this paper, we show that upon heat shock, HSF1 concentrates in the nucleus of diploid human fibroblasts in two large foci. The relative distribution of HSF1 nuclear foci and active heat shock protein (hsp) genes was investigated by combining fluorescence in situ hybridization (FISH) for the detection of hsp nuclear transcripts and immunofluorescence for the detection of HSF1. We show that the HSF1 foci are distinct from the sites of hsp70 and hsp90 genes transcription. This is the second report of ploidy-dependent foci of transcription factors that are independent of their specific transcription sites. However, the correlation between the number of HSF1 foci and the ploidy of the cells strongly supports the existence of a specific chromosomal target for HSF1 foci.