Breaking Bad Proteins-Discovery Approaches and the Road to Clinic for Degraders

Proteolysis-targeting chimeras (PROTACs) describe compounds that bind to and induce degradation of a target by simultaneously binding to a ubiquitin ligase. More generally referred to as bifunctional degraders, PROTACs have led the way in the field of targeted protein degradation (TPD), with several compounds currently undergoing clinical testing. Alongside bifunctional degraders, single-moiety compounds, or molecular glue degraders (MGDs), are increasingly being considered as a viable approach for development of therapeutics, driven by advances in rational discovery approaches. This review focuses on drug discovery with respect to bifunctional and molecular glue degraders within the ubiquitin proteasome system, including analysis of mechanistic concepts and discovery approaches, with an overview of current clinical and pre-clinical degrader status in oncology, neurodegenerative and inflammatory disease.

The PIG-A gene mutation assay in human biomonitoring and disease

The blood cell phosphatidylinositol glycan class A (PIG-A) gene mutation assay has been extensively researched in rodents for in vivo mutagenicity testing and is now being investigated in humans. The PIG-A gene is involved in glycosyl phosphatidylinositol (GPI)-anchor biosynthesis. A single mutation in this X-linked gene can lead to loss of membrane-bound GPI anchors, which can be enumerated via corresponding GPI-anchored proteins (e.g., CD55) using flow cytometry. The studies published to date by different research groups demonstrate a remarkable consistency in PIG-A mutant frequencies. Moreover, with the low background level of mutant erythrocytes in healthy subjects (2.9-5.56 × 10-6 mutants), induction of mutation post genotoxic exposure can be detected. Cigarette smoking, radiotherapy, and occupational exposures, including lead, have been shown to increase mutant levels. Future applications of this test include identifying new harmful agents and establishing new exposure limits. This mutational monitoring approach may also identify individuals at higher risk of cancer development. In addition, identifying protective agents that could mitigate these effects may reduce baseline somatic mutation levels and such behaviors can be encouraged. Further technological progress is required including establishing underlying mechanisms of GPI anchor loss, protocol standardization, and the development of cryopreservation methods to improve GPI-anchor stability over time. If successful, this assay has the potential be widely employed, for example, in rural and low-income countries. Here, we review the current literature on PIG-A mutation in humans and discuss the potential role of this assay in human biomonitoring and disease detection.

Protocol for a prospective study evaluating circulating tumour cells status to predict radical prostatectomy treatment failure in localised prostate cancer patients (C-ProMeta-1)

BACKGROUND

Treatment decisions in prostate cancer (PCa) rely on disease stratification between localised and metastatic stages, but current imaging staging technologies are not sensitive to micro-metastatic disease. Circulating tumour cells (CTCs) status is a promising tool in this regard. The Parsortix® CTC isolation system employs an epitope-independent approach based on cell size and deformability to increase the capture rate of CTCs. Here, we present a protocol for prospective evaluation of this method to predict post radical prostatectomy (RP) PCa cancer recurrence.

METHODS

We plan to recruit 294 patients diagnosed with unfavourable intermediate, to high and very high-risk localised PCa. Exclusion criteria include synchronous cancer diagnosis or prior PCa treatment, including hormone therapy. RP is performed according to the standard of care. Two blood samples (20 ml) are collected before and again 3-months after RP. The clinical team are blinded to CTC results and the laboratory researchers are blinded to clinical information. Treatment failure is defined as a PSA ≥ 0.2 mg/ml, start of salvage treatment or imaging-proven metastatic lesions. The CTC analysis entails enumeration and RNA analysis of gene expression in captured CTCs. The primary outcome is the accuracy of CTC status to predict post-RP treatment failure at 4.5 years. Observed sensitivity, positive and negative predictive values will be reported. Specificity will be presented over time.

DISCUSSION

CTC status may reflect the true potential for PCa metastasis and may predict clinical outcomes better than the current PCa progression risk grading systems. Therefore establishing a robust biomarker for predicting treatment failure in localized high-risk PCa would significantly enhance guidance in treatment decision-making, optimizing cure rates while minimizing unnecessary harm from overtreatment.

TRIAL REGISTRATION

ISRCTN17332543.

Circulating tumour cells for early detection of clinically relevant cancer

Given that cancer mortality is usually a result of late diagnosis, efforts in the field of early detection are paramount to reducing cancer-related deaths and improving patient outcomes. Increasing evidence indicates that metastasis is an early event in patients with aggressive cancers, often occurring even before primary lesions are clinically detectable. Metastases are usually formed from cancer cells that spread to distant non-malignant tissues via the blood circulation, termed circulating tumour cells (CTCs). CTCs have been detected in patients with early stage cancers and, owing to their association with metastasis, might indicate the presence of aggressive disease, thus providing a possible means to expedite diagnosis and treatment initiation for such patients while avoiding overdiagnosis and overtreatment of those with slow-growing, indolent tumours. The utility of CTCs as an early diagnostic tool has been investigated, although further improvements in the efficiency of CTC detection are required. In this Perspective, we discuss the clinical significance of early haematogenous dissemination of cancer cells, the potential of CTCs to facilitate early detection of clinically relevant cancers, and the technological advances that might improve CTC capture and, thus, diagnostic performance in this setting.

Measuring blood cell DNA damage using the PIG-A mutation and CBMN assay in pancreatic cancer patients: a pilot study

Pancreatic cancer still has one of the worst prognoses of all solid malignancies, despite developments in cancer knowledge and care. Research into pancreatic cancer has not fully translated into clinical improvements and as a result, fewer than 1% of patients survive 10 years post-diagnosis. This bleak outlook for patients could be improved by earlier diagnosis. The human erythrocyte phosphatidylinositol glycan class A (PIG-A) assay monitors the mutation status of the X-linked PIG-A gene by measuring glycosyl phosphatidylinositol (GPI)-anchored proteins on the extracellular surface. We have previously identified an elevated PIG-A mutant frequency in oesophageal adenocarcinoma patients and here investigate whether this could be seen in a pancreatic cancer cohort, given the urgent need for novel pancreatic cancer biomarkers. In our pilot study, an elevated PIG-A mutant frequency (5.775 × 10-6 (95% CI 4.777-10) mutants per million) was seen in pancreatic cancer patients (n = 30) when compared to the non-cancer control group (n = 14) who had an erythrocyte mutant frequency of 4.211 × 10-6 (95% CI 1.39-5.16) mutants per million (p = 0.0052). A cut-off value of 4.7 mutants per million provided an AUROC of 0.7595 with a sensitivity of 70% and specificity of 78.57%. A secondary measure of DNA damage in an alternative blood cell population also showed an increase in peripheral lymphocytes using the cytokinesis-block micronucleus assay (p = 0.0164) (AUROC = 0.77, sensitivity = 72.22%, specificity = 72.73%). The micronucleus frequency and PIG-A status show some potential as blood-based biomarkers of pancreatic cancer, but further investigations of these DNA damage tests are required to assess their utility in pancreatic cancer diagnosis.

Abstract 6302: Structure-based and property-based drug design of AZD9574, a CNS penetrant PARP1 selective inhibitor and trapper

PARP inhibitors exploit defects in DNA repair pathways to selectively target cancerous cells via PARP1 catalytic inhibition and PARP1 trapping onto the DNA. All known clinical PARP1 inhibitors bind at the same site at the catalytic center of the enzyme. However, despite this resemblance they show immensely different outcomes in terms of response rate in the clinic due to their varying degree of PARP trapping ability. Moreover, the first-generation PARP inhibitors were not optimized for selectivity across the PARP family potentially driving undesirable side effects, including intestinal toxicity from tankyrase inhibition or hematological toxicity from PARP2 inhibition. There has been strong rationale for the use of PARP inhibitors in neuro-oncology. However, the first-generation PARP inhibitors have limited CNS distribution as these drugs were not designed for brain penetration. Recently AstraZeneca has reported the discovery of AZD5305, a next generation PARP1 selective inhibitor and PARP1-DNA trapper which was not designed with a CNS penetrant profile. Given the unmet need of a brain penetrant PARP1 inhibitor, we set out to identify a highly potent and selective PARP1 inhibitor and trapper with CNS profile. In our next generation PARP1 inhibitor, we sought to retain the profile of AZD5305 and lower the efflux for CNS penetration. Despite the challenge of narrow SAR, we successfully used the structure- and property-based design approach to identify a brain penetrant PARP1 inhibitor and PARP1-DNA trapper. We used multiple medicinal chemistry maneuvers such as masking the hydrogen bond donors and core modifications to lower the efflux in order to achieve brain penetration. Further optimization of the nicotinamide mimetic core for potency and metabolic stability led us to the discovery of AZD9574.AZD9574 shows improved selectivity for PARP1 over PARP2 vs AZD5305 and retains its excellent selectivity over other PARP family members. It has low efflux in Caco2, MDCK-MDR1, and MDCK-MDR1-BCRP permeability assays and it also showed CNS penetration in rat and cynomolgus monkey. AZD9574 has excellent secondary pharmacology and acceptable physicochemical properties and good PK in preclinical species.In vitro, AZD9574 selectively inhibits the growth of BRCAm cell lines. Importantly, AZD9574 showed efficacy in an intracranial BRCA1m MDA-MB-436 xenograft model at doses of 3, 10 and 30 mg/kg QD, significantly extending the survival of tumor-bearing mice compared to vehicle control arm.In summary, AZD9574 is a next generation selective PARP1 inhibitor and trapper with CNS penetration. This profile makes it an ideal candidate for treating CNS malignancies or brain metastases that have a dependence on PARP inhibition either as single agent or in combination with other therapies.

Citation Format: Avipsa Ghosh, Sudhir M. Hande, Amber Balazs, Derek Barratt, Sabina Cosulich, Barry Davies, Sébastien Degorce, Kevin Embrey, Sonja Gill, Anders Gunnarsson, Giuditta Illuzzi, Peter Johnström, Jordan Lane, Carrie Larner, Rachel Lawrence, Elisabetta Leo, Andrew Madin, Elizabeth Martin, Lisa McWilliams, Lenka O’Connor, Mark O’Connor, Jonathan Orme, Fiona Pachl, Martin Packer, Andy Pike, Philip Rawlins, Marianne Schimpl, Magnus Schou, Anna Staniszewska, Wenzhan Yang, James Yates, Andrew Zhang, XiaoLa Zheng, Stephen Fawell, Petra Hamerlik, Jeffrey Johannes. Structure-based and property-based drug design of AZD9574, a CNS penetrant PARP1 selective inhibitor and trapper [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6302.

1019 Quantified Learning Curves for Robotic Gastrointestinal Surgery

Aim

Robotic techniques are increasingly being adopted by gastrointestinal surgeons. It is important to understand the learning curves (LCs) for robotic surgery, to protect patients from harm caused by surgeon inexperience.

The aim of this study was to summarise reports of the LC for three robotic gastrointestinal procedures: cholecystectomy, oesophagectomy and Roux-en-Y gastric bypass (RYGB).

Method

Three systematic reviews were conducted by the trainee led RoboSurg Collaborative. Systematic searches identified reports of primary clinical research involving robotic cholecystectomy, oesophagectomy and RYGB. Articles were screened in duplicate by title, abstract and then full text. References to the LC were extracted and coded. Quantifications of the learning curve were summarised using descriptive statistics.

Results

259 articles were identified: 56 measured the LC, with 23 (9%) of these calculating the number of cases required to complete the LC. The mean reported number of cases at which the LC plateaued was: 16 for oesophagectomy (N = 6, SD = 3.7), 18 for cholecystectomy (N = 5, SD = 15.1), 34 for RYGB (N = 12, SD = 24.6). The reported LCs often incorporated equipment setup times, and so represents learning of the team as well as the surgeon. These values represent points on the LC that authors deemed their surgeons to have ‘completed’ learning. Definitions for when these points occurred varied greatly but largely fell in to two categories: ‘plateau of operative time’ or ‘matching operating time of laparoscopic control procedure’.

Conclusions

The heterogeneity in how LCs are defined, measured, and reported highlights the need for a more standardised approach when evaluating novel techniques such as robotics.

1028 How Has the Learning Curve Been Measured in Robotic Gastrointestinal Surgery?

Aim

Robotic surgery is increasingly being adopted by gastrointestinal surgeons. The IDEAL Collaboration has recommended evaluation of the learning curve (LC) for such surgical innovations. It is not known how learning curves have been reported for robotic gastrointestinal procedures. The aim of this study was to summarise how the LCs were measured for three robotic gastrointestinal procedures: cholecystectomy, oesophagectomy and Roux-en-Y gastric bypass (RYGB).

Method

Three systematic reviews conducted by the trainee led RoboSurg Collaborative identified primary clinical research involving robotic cholecystectomy, oesophagectomy and RYGB. Articles were screened in duplicate by title, abstract and then full text. References to the LC were extracted and coded. The techniques used to measure the LC were summarised using descriptive statistics.

Results

259 articles were identified, of which 56 (22%) actively measured the LC. The commonest surrogate marker for performance was operative time (N = 34, 63%). Several evaluated performances using the cumulative sum of the operative times (N = 8, 14%). Complications (N = 5, 8%) and time to complete a specific surgical step (N = 4, 7%) were also used. Some authors used multiple markers (N = 4, 7%). Cases were reported individually in 48 (81%) of the LCs, whereas they were grouped in 11 (19%). 19 authors (34%) provided graphical representation of the LC.

Conclusions

The reporting of LCs for robotic gastrointestinal surgery was heterogeneous and lacked standardisation. There was variation in choice of surrogate markers for performance, individual versus grouped case reporting, and graphical representations. To improve the utility of LC reports, the recommendations of the IDEAL Collaboration should be implemented.

Postmortem Analyses in a Patient With Succinic Semialdehyde Dehydrogenase Deficiency (SSADHD): II. Histological, Lipid, and Gene Expression Outcomes in Regional Brain Tissue

This study has extended previous metabolic measures in postmortem tissues (frontal and parietal lobes, pons, cerebellum, hippocampus, and cerebral cortex) obtained from a 37-year-old male patient with succinic semialdehyde dehydrogenase deficiency (SSADHD) who expired from SUDEP (sudden unexplained death in epilepsy). Histopathologic characterization of fixed cortex and hippocampus revealed mild to moderate astrogliosis, especially in white matter. Analysis of total phospholipid mass in all sections of the patient revealed a 61% increase in cortex and 51% decrease in hippocampus as compared to (n = 2-4) approximately age-matched controls. Examination of mass and molar composition of major phospholipid classes showed decreases in phospholipids enriched in myelin, such as phosphatidylserine, sphingomyelin, and ethanolamine plasmalogen. Evaluation of gene expression (RT² Profiler PCR Arrays, GABA, glutamate; Qiagen) revealed dysregulation in 14/15 GABA_A receptor subunits in cerebellum, parietal, and frontal lobes with the most significant downregulation in ∊, θ, ρ1, and ρ2 subunits (7.7-9.9-fold). GABA_B receptor subunits were largely unaffected, as were ionotropic glutamate receptors. The metabotropic glutamate receptor 6 was consistently downregulated (maximum 5.9-fold) as was the neurotransmitter transporter (GABA), member 13 (maximum 7.3-fold). For other genes, consistent dysregulation was seen for interleukin 1β (maximum downregulation 9.9-fold) and synuclein α (maximal upregulation 6.5-fold). Our data provide unique insight into SSADHD brain function, confirming astrogliosis and lipid abnormalities previously observed in the null mouse model while highlighting long-term effects on GABAergic/glutamatergic gene expression in this disorder.

Dietary and lifestyle factors effect erythrocyte PIG-A mutant frequency in humans

It is well understood that poor diet and lifestyle choices can increase the risk of cancer. It is also well documented that cancer is a disease of DNA mutations, with mutations in key genes driving carcinogenesis. Measuring these mutations in a minimally invasive way may be informative as to which exposures are harmful and thus allow us to introduce primary preventative measures, in a bid to reduce cancer incidences. Here, we have measured mutations in the phosphatidylinositol glycan class A (PIG-A) gene in erythrocytes from healthy volunteers (n = 156) and from non-cancer patients attending the local endoscopy department (n = 144). The X-linked PIG-A gene encodes an enzyme involved in glycosylphosphatidylinositol (GPI) anchor synthesis. A silencing mutation in which leads to the absence of GPI anchors on the extracellular surface which can be rapidly assessed using flow cytometry. The background level of PIG-A mutant erythrocytes was 2.95 (95% CI: 2.59-3.67) mutant cells (10-6). Older age increased mutant cell frequency (P < 0.001). There was no difference in mutant cell levels between males and females (P = 0.463) or smokers and non-smokers (P = 0.186). In the endoscopy group, aspirin users had lower mutant frequencies (P = 0.001). Further information on diet and exercise was available for the endoscopy patient group alone, where those with a higher health promotion index score had lower mutant frequencies (P = 0.011). Higher dietary intake of vegetables reduced mutant cell levels (P = 0.022). Participants who exercised for at least 1 h a week appeared to have reduced mutant frequencies than those who did not exercise, although this was not statistically significant (P = 0.099). This low background level of mutant erythrocytes in a population makes this assay an attractive tool to monitor exposures such as those associated with lifestyles and diet, as demonstrated here.

Abstract 1757: Developing sensitive assays to facilitate hit identification of RNA modifying enzymes

N-6-methyladenosine (m6A) is the most abundant RNA chemical modification found in the eukaryotic transcriptome. It is a dynamic and reversible modification which plays a role in RNA function across a wide range of biological processes. Dysregulation of the m6A modification and the readers, writers and erasers involved in these processes have been implicated in the progression of multiple types of cancer and metabolic disease. RNA modifying enzymes are therefore emerging as exciting therapeutic targets.

To facilitate and accelerate drug discovery efforts in this area, we have developed several sensitive and robust assays suitable for identifying and assessing chemical matter against the RNA modifying enzymes, fat mass and obesity associated protein (FTO) and methyltransferase-like 3/14 (METTL3/14). Specifically, a robust Microscale Thermophoresis (MST) assay was developed, validated, and used to screen 100 compounds from the LOPAC for novel human FTO small molecule binders. Five compounds, which displayed reproducible, concentration-dependent binding in the MST screen, were tested for inhibition of human FTO RNA demethylation activity and revealed a single, novel FTO inhibitor. To further profile emerging FTO hit matter, we are also developing sensitive and robust mass spectrometry assays to demonstrate target inhibition and proof of mechanism. Our progress in this area will be reported. Additionally, we have developed a highly sensitive and robust LC-MS/MS assay to monitor the METTL3/14 catalysed conversion of S-adenosylmethionine (SAM) to S-adenosylhomocysteine (SAH). This assay is suitable for identifying either substrate competitive or allosteric METTL3/14 inhibitors.

In summary, our proof of concept studies describe the development of several robust and sensitive assays suitable for hit identification and further characterisation of inhibitors of key RNA modifying enzymes and offer a platform for the discovery and development of novel therapeutics in this emerging area of research.

Citation Format: Chris Tomlinson, Rachel Lawrence, Stuart Best, Grace Boden, Thomas Alanine, James Wasp, Bethany Smith, Ross Wilkie, Stuart Thomson, John Unitt, Scott Pollack, Allan M. Jordan. Developing sensitive assays to facilitate hit identification of RNA modifying enzymes [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1757.

Systematic review to determine which validated measurement tools can be used to assess risk of problematic analgesic use in patients with chronic pain

Background

Misuse of prescription opioids, and other drugs prescribed for chronic pain, has increased, with major concerns about harm. This review was undertaken to identify validated measurement tools for risk assessment and monitoring of chronic non-cancer pain patients being considered for, or currently prescribed, analgesic drugs with abuse potential.

Methods

Selected databases (Embase, Medline, Cochrane library/CENTRAL, PsycINFO, PubMed, CINAHL) were systematically searched for studies evaluating tools for risk of analgesic misuse, either before, or during, analgesic therapy for chronic pain, using predetermined inclusion/exclusion criteria. Two independent reviewers assessed abstracts, selected full texts, extracted data and assessed quality.

Results

30 studies from 1844 met inclusion criteria, including three systematic reviews, with an additional four studies from bibliography review. The studies covered 14 tools pertaining to opioid use, with none for non-opioid analgesics.

Conclusions

For predicting prescription opioid misuse, the pain medication questionnaire (PMQ) and the screener and opioid assessment for patients with pain (SOAPP) had the best evidence; both developed and validated in five separate studies (four each of acceptable quality). The current opioid misuse measure (COMM) performed best screening for current misuse, developed and validated in three studies of acceptable quality. A small number of tools may accurately predict, or identify, opioid misuse. There are none for non-opioid analgesics, where there is a potential need.

Abstract OT3-02-08: Open label, phase 2 safety, efficacy, and pharmacokinetic study of pre-surgical intramuscular and intraductal fulvestrant in women with invasive breast cancer or DCIS undergoing mastectomy or lumpectomy

BACKGROUND: Breast cancer (BC) is the leading cause of cancer in women in the United States and the second leading cause of cancer-related death. Currently available options for prevention are oophorectomy, bilateral mastectomy, or medical therapy, such as tamoxifen, raloxifene or aromatase inhibitors. None of these options for prevention are without significant side effects with low patient uptake. This study proposes fulvestrant instilled directly into the breast via the nipple orifices as intraductal therapy. Providing a local therapy into the ducts could reduce the morbidity associated with prevention while potentially better targeting the carcinoma cell. Building on prior studies with cytotoxic agents, this study utilizes the pure anti-estrogen fulvestrant to be injected in up to 5 ducts to determine its effect on BC as well as the safety of this method of administration.

TRIAL DESIGN: An open-label, non-randomized PK study of pre-surgical fulvestrant in women scheduled for mastectomy or lumpectomy. Eligible subjects will be undergoing mastectomy or lumpectomy. The first 6 subjects will be treated with the standard dose of 500 mg intramuscular fulvestrant to establish the reference PK curve. The subsequent 24 subjects will receive fulvestrant by intraductal instillation. Subjects where at least 1 suitable duct is identified will undergo nipple aspiration in order to facilitate duct identification and intraductal infusion of a fulvestrant. A maximum of 5 ducts will receive intraductal infusion of fulvestrant. Across all ducts, the total dose will not exceed 500 mg (10 mL). Subsequent to mastectomy or lumpectomy subjects will undergo serial blood draws to determine fulvestrant blood concentration levels and tissue drug levels.

ELIGIBILITY: Female, age &gt; 18, mastectomy/lumpectomy scheduled within 30 days, Stage 1/2, ER+ low grade invasive BC or DCIS, ECOG scale 0-1.

Primary Objective: The safety and tolerability of intraductal administration of fulvestrant in women with Stage 1 or 2 invasive ductal carcinoma or DCIS, prior to mastectomy or lumpectomy.

Secondary Objectives: The pathological effects, specifically changes in Ki67, ER/PgR expression between pre-fulvestrant biopsy and post-fulvestrant surgical specimen.

STATISTICAL METHODS: Aim of this study is to assess safety and tolerability in subjects receiving intraductal fulvestrant. In addition this trial aims to characterize the PK of this alternative route of administration, and compare the intraductal PK profile to that of standard intramuscular administration. Finally, the 6 study subjects who receive intramuscular fulvestrant will be qualitatively compared with the main study cohort of 24 subjects who receive intraductal fulvestrant. Change in Ki67 labeling index will be compared between the two time points (baseline or time of diagnostic biopsy v. time of the surgically excised specimen collection).

CONTACT INFO: Sheldon Marc Feldman MD Columbia University Medical Center sf2388@cumc.columbia.edu 212-305-9676.

Citation Format: Feldman S, Gomberawalla A, Alonso A, Rea J, Quay S, Lawrence R. Open label, phase 2 safety, efficacy, and pharmacokinetic study of pre-surgical intramuscular and intraductal fulvestrant in women with invasive breast cancer or DCIS undergoing mastectomy or lumpectomy [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 OT3-02-08.

Analgesic drugs and the gut - a reciprocal relationship

Analgesic drugs, as well as providing pain relief, can cause a range of other symptoms and side effects, most notably on the gastrointestinal system. Conversely, gastrointestinal disease will often require analgesia, and this can be complicated by the fact that the gut is the site of absorption of oral drugs. This paper discusses some of the effects of common oral analgesic drugs on the gastrointestinal tract and their role in managing some of the most common, nonmalignant, chronic gastrointestinal disorders in adults.

Persistent Mycobacterium bovis-BCG is resistant to glutathione induced reductive stress killing

This study focuses on the redox stress response in mycobacteria elicited by a host-derived, thiol-based detoxification molecule, glutathione (GSH). Although the growth and viability of Mycobacterium bovis-BCG (BCG) was hampered by exposure to 8 mM GSH, oxygen depleted, persistent BCG (NRP BCG) resisted GSH-mediated killing. Fast growing mycobacteria also resisted GSH-mediated killing. To determine the mechanisms behind these observations, we evaluated the levels of intracellular ATP in both BCG and NRP BCG exposed to 8 mM GSH. Intracellular ATP levels increased from 0.13 to 2.3 μM in BCG upon exposure to GSH. The levels of ATP remained low and unchanged when NRP BCG was exposed to GSH. Using both HPLC and a cell-based thiol detection assay, it was determined that GSH stimulates the production of mycothiol (MSH) by BCG approximately 5.7 fold. The levels of MSH did not change upon exposure of NRP BCG to GSH. MSH is an alternative, thiol-based detoxification molecule employed by mycobacteria. Changes in the cytoplasmic concentrations of this molecule are suggestive of redox imbalances. Together, GSH and MSH may introduce excess reducing equivalents into the mycobacterial cytoplasm; leading to reductive stress. The modulation of NAD(+) levels through alterations in ATP metabolism can enhance the cells ability to bind excess reducing equivalents and serve as a mechanism to restore the cellular redox balance when cells experience reductive stress. These data suggest that killing of BCG by GSH may result from reductive stress that cannot be controlled. NRP BCG appears to be resistant to GSH-induced reductive stress.

Controversies in the management of sudden sensorineural hearing loss: an evidence-based review

BACKGROUND

Sudden sensorineural hearing loss (SSNHL) is considered an otological emergency. It may present as an isolated condition or be the presenting feature of a systemic disease process. Idiopathic sudden sensorineural hearing loss (ISSNHL) is diagnosed when an underlying cause or condition cannot be identified.

OBJECTIVE OF REVIEW

To review the current literature on SSNHL and propose a treatment algorithm based on the highest quality evidence.

SEARCH STRATEGY AND TYPE OF REVIEW

An evidence-based literature review using medline (search terms 'sudden sensorineural hearing loss' and 'acute sensorineural hearing loss').

RESULTS

(i) Baseline Investigations: All patients should be assessed with a thorough history and examination. This should include a pure tone audiogram (PTA) where possible. Baseline and targeted laboratory tests should be carried out to diagnose specific conditions. (ii) Imaging: MRI should be carried out in all cases of ISSNHL. If MRI imaging is contraindicated either CT or auditory brainstem response (ABR) testing should be performed. (iii) Medical Management: If a specific cause for a SSNHL is found, the patient should be managed accordingly. If idiopathic in nature, patients may be offered a course of oral steroid. If systemic steroids are contraindicated and/or there is no improvement with initial oral therapy, intratympanic steroids (IT) as either primary or salvage therapy may be considered. (iv) Further Management: There is no evidence to support the routine use of antiviral therapy. The cost, limited availability and lack of strong evidence for hyperbaric oxygen therapy (HBOT) make it impractical at present. Due to the variability in the vasodilator and vasoactive agents used, there is insufficient evidence to support the routine use of these agents. Consideration should be given to both temporary and permanent hearing amplification when required.

CONCLUSIONS

SSNHL is an important condition that can have a significant impact on quality of life. Some patients respond spontaneously without intervention; however, evidence tells us that certain interventions such as corticosteroid treatment may improve outcomes. Further high-quality research is required. Meanwhile, an interim indicative treatment algorithm for SSNHL based on the current best evidence available is outlined.

Leiomyosarcoma of the inguinal canal

We describe a rare case of a leiomyosarcoma in the inguinal canal in a patient presenting clinically with an inguinal hernia. The clinical details, histological findings and surgical management are reviewed.

Examining the overlap between genome-wide rare variant association signals and linkage peaks in rheumatoid arthritis

OBJECTIVE

With the exception of the major histocompatibility complex (MHC) and STAT4, no other rheumatoid arthritis (RA) linkage peak has been successfully fine-mapped to date. This apparent failure to identify association under peaks of linkage could be ascribed to the examination of common variation, when linkage is likely to be driven by rare variants. The purpose of this study was to investigate the overlap between genome-wide rare variant RA association signals observed in the Wellcome Trust Case Control Consortium (WTCCC) study and 11 replicating RA linkage peaks, defined as regions with evidence for linkage in >1 study.

METHODS

The WTCCC data set contained 40,482 variants with minor allele frequency of ≤0.05 in 1,860 RA patients and 2,938 controls. Genotypes of all rare variants within a given gene region were collapsed into a single locus and a global P value was calculated per gene.

RESULTS

The distribution of rare variant signals (association P≤10(-5)) was found to differ significantly between regions with and without linkage evidence (P=2×10(-17) by Fisher's exact test). No significant difference was observed after data from the MHC region were removed or when the effect of the HLA-DRB1 locus was accounted for.

CONCLUSION

The results suggest that rare variant association signals are significantly overrepresented under linkage peaks in RA, but the effect is driven by the MHC. This is the first study to examine the overlap between linkage peaks and rare variant association signals genome-wide in a complex disease.

Case-Based Subgoaling in Real-Time Heuristic Search for Video Game Pathfinding

Real-time heuristic search algorithms satisfy a constant bound on the amount of planning per action, independent of problem size. As a result, they scale up well as problems become larger. This property would make them well suited for video games where Artificial Intelligence controlled agents must react quickly to user commands and to other agents' actions. On the downside, real-time search algorithms employ learning methods that frequently lead to poor solution quality and cause the agent to appear irrational by re-visiting the same problem states repeatedly. The situation changed recently with a new algorithm, D LRTA*, which attempted to eliminate learning by automatically selecting subgoals. D LRTA* is well poised for video games, except it has a complex and memory-demanding pre-computation phase during which it builds a database of subgoals. In this paper, we propose a simpler and more memory-efficient way of pre-computing subgoals thereby eliminating the main obstacle to applying state-of-the-art real-time search methods in video games. The new algorithm solves a number of randomly chosen problems off-line, compresses the solutions into a series of subgoals and stores them in a database. When presented with a novel problem on-line, it queries the database for the most similar previously solved case and uses its subgoals to solve the problem. In the domain of pathfinding on four large video game maps, the new algorithm delivers solutions eight times better while using 57 times less memory and requiring 14% less pre-computation time.

Effect of shade on body temperature and performance of feedlot steers

A 120-d feedlot study using 164 Angus steers (BW = 396.7 ± 7.0 kg) was undertaken in Queensland Australia (24°84' S, 149°78' N) to determine the effect of shade on body temperature (T(B)) and performance. Cattle were allocated to 20 pens: 16 with an area of 144 m(2) (8 steers/pen) and 4 with an area of 168 m(2) (9 steers/pen). Treatments (10 pens/treatment) were unshaded (NS) vs. shaded (SH). Shade (3.3 m(2)/steer) was provided by 80% solar block shade cloth. Before the study (d -31), 63 steers were implanted (between the internal abdominal muscle and the peritoneum at the right side flank) with a T(B) transmitter. Within each pen, 3 steers had a T(B) transmitter. Individual T(B) was obtained every 30 min. The cattle were fed a feedlot diet and had ad libitum access to water. Water usage and DMI were recorded daily on a pen basis. Average daily gain and G:F were calculated on a pen basis. Climatic variables were obtained from an on-site weather station every 30 min. Individual panting scores (PS) were obtained daily at 0600, 1200, and 1600 h. From these, mean PS (MPS) were calculated for each pen. At slaughter (d 121), individual HCW, loin muscle area (LMA), rump fat depth (P8), 12th-rib fat depth, and marbling score were obtained. Mean T(B) was not affected (P > 0.05) by treatment (SH = 39.58°C; NS = 39.60°C). However, during a 21-d heat wave when cattle were exposed to a mean ambient temperature (T(AM)) > 30°C for 8 h each d (T(AM) between 0800 and 1800 h = 29.7°C, and 23.4°C between 1830 and 0730 h), the T(B) of SH steers (40.41 ± 0.10°C) was less (P < 0.01) than the T(B) of NS steers (41.14 ± 0.10°C). During this period, pen-MPS were greater (P < 0.05) for the NS cattle at all observation times. Over the first 6 d of the heat wave, MPS of NS steers at 1200 h was 2.47 (P < 0.01) vs. 1.39 for SH steers. Hip height, DMI, ADG, and G:F were greater (P < 0.05) for SH cattle. Exit BW (final BW) of SH steers (596.1 kg) was greater (P < 0.05) when compared with NS steers (578.6 kg). During the heat wave, DMI was 51% less for NS steers and 39% less for SH steers when compared with the pre-heat wave period (P < 0.01). The HCW of SH steers (315.4 ± 0.8 kg) was greater (P < 0.05) than for NS steers (321.4 ± 0.8 kg). No treatment differences (P > 0.05) were found for LMA, P8, or marbling score. Access to shade improved (P < 0.05) ADG and G:F, increased HCW, and decreased MPS; however, shade did not completely eliminate the impact of high heat load.

Group cognitive behavioural therapy for schizophrenia: a systematic review of the literature

There are a growing number of studies which have evaluated group-based cognitive behavioural therapy (CBGT) for individuals with psychosis. This is at least partly driven by the need to maximize access to this evidence-based treatment which has still to be widely disseminated. In this paper we present a systematic review of trials which have evaluated the efficacy CBGT. Five controlled trials were identified, the results showed some improvements in specific areas of symptomatology such as social phobia and depression. However, methodological weaknesses of the studies compromised the confidence with which a cause and effect relationship can be established. CBGT may enable a greater number of individuals to be seen by a small group of trained therapists but whether this is an effective treatment remains to be established. In addition, whether therapists delivering cognitive behavioural therapy in a group format require a higher level of skill than those facilitating the intervention on an individual basis remains an empirical question. The finding that a short psycho-education group treatment reduced positive and negative symptoms is also worthy of further investigation given the difficulties reported in disseminating evidence-based psychosocial interventions for this client group.

Limits on gravitational-wave emission from selected pulsars using LIGO data

We place direct upper limits on the amplitude of gravitational waves from 28 isolated radio pulsars by a coherent multidetector analysis of the data collected during the second science run of the LIGO interferometric detectors. These are the first direct upper limits for 26 of the 28 pulsars. We use coordinated radio observations for the first time to build radio-guided phase templates for the expected gravitational-wave signals. The unprecedented sensitivity of the detectors allows us to set strain upper limits as low as a few times 10(-24). These strain limits translate into limits on the equatorial ellipticities of the pulsars, which are smaller than 10(-5) for the four closest pulsars.

Submucous lipoma of the ileocaecal valve presenting as caecal volvulus

Caecal volvulus is a well described but unusual condition. We report here, a case of caecal volvulus in a 53-year-old Caucasian woman associated with intussuscepted submucous lipoma of the ileocaecal region. The imaging and pathology are presented. Submucous lipoma of the ileocaecal region is uncommon but well described. It can be mistaken as carcinoma of the ascending colon on barium enema and on computed tomography scan. The combination with caecal volvulus is a rare occurrence.

Chromosome-wide distribution of haplotype blocks and the role of recombination hot spots

Recent studies of human populations suggest that the genome consists of chromosome segments that are ancestrally conserved ('haplotype blocks'; refs. 1-3) and have discrete boundaries defined by recombination hot spots. Using publicly available genetic markers, we have constructed a first-generation haplotype map of chromosome 19. As expected for this marker density, approximately one-third of the chromosome is encompassed within haplotype blocks. Evolutionary modeling of the data indicates that recombination hot spots are not required to explain most of the observed blocks, providing that marker ascertainment and the observed marker spacing are considered. In contrast, several long blocks are inconsistent with our evolutionary models, and different mechanisms could explain their origins.