A retrospective study of subcutaneous anchor securement systems in oncology patients.

INTRODUCTION: Maintaining optimal central venous catheter tip position requires reliable catheter securement. A vital decision about the choice of engineered securement device is often made by what is conveniently available in the insertion kit or default clinical routine. The importance of continuous securement for oncology patients prompted the need for an evaluation of securement options currently available. This study aimed to assess the effectiveness of two engineered securement devices to assist the oncology patient in reaching the end of their catheter need. METHODS: A retrospective study was conducted to assess patients' ability to finish their therapy with one peripherally inserted central catheter. Implant and explant data for adult oncology patients was evaluated spanning 2007-2021. All patients received a PICC with either an adhesive securement device or a subcutaneous anchor securement system. RESULTS: Partial or complete dislodgement causing the unplanned removal of the PICC occurred at 12% for ASD and 0.4% for SASS (p < 0.0001). The probability of reaching the end of need with one PICC, regardless of the reason for premature removal, at 2 years for patients with an adhesive securement device was 68% (n = 944). For patients with a subcutaneous anchored securement device, it was over 95% (n = 8313). The difference in the probability of reaching the end of the need with one PICC between the two securement devices was calculated at (p < 0.0001). CONCLUSION: With over 9200 patients and more than a million catheter days, the results of this retrospective study demonstrate the SASS's superiority in assisting the patient to reach the end of need with a single PICC.

Serum Proteomics and Plasma Fibulin-3 in Differentiation of Mesothelioma From Asbestos-Exposed Controls and Patients With Other Pleural Diseases.

INTRODUCTION: Malignant pleural mesothelioma (MPM) is difficult to diagnose. An accurate blood biomarker could prompt specialist referral or be deployed in future screening. In earlier retrospective studies, SOMAscan proteomics (Somalogic, Boulder, CO) and fibulin-3 seemed highly accurate, but SOMAscan has not been validated prospectively and subsequent fibulin-3 data have been contradictory. METHODS: A multicenter prospective observational study was performed in 22 centers, generating a large intention-to-diagnose cohort. Blood sampling, processing, and diagnostic assessment were standardized, including a 1-year follow-up. Plasma fibulin-3 was measured using two enzyme-linked immunosorbent assays (CloudClone [used in previous studies] and BosterBio, Pleasanton, CA). Serum proteomics was measured using the SOMAscan assay. Diagnostic performance (sensitivity at 95% specificity, area under the curve [AUC]) was benchmarked against serum mesothelin (Mesomark, Fujirebio Diagnostics, Malvern, PA). Biomarkers were correlated against primary tumor volume, inflammatory markers, and asbestos exposure. RESULTS: A total of 638 patients with suspected pleural malignancy (SPM) and 110 asbestos-exposed controls (AECs) were recruited. SOMAscan reliably differentiated MPM from AECs (75% sensitivity, 88.2% specificity, validation cohort AUC 0.855) but was not useful in patients with differentiating non-MPM SPM. Fibulin-3 (by BosterBio after failed CloudClone validation) revealed 7.4% and 11.9% sensitivity at 95% specificity in MPM versus non-MPM SPM and AECs, respectively (associated AUCs 0.611 [0.557-0.664], p = 0.0015) and 0.516 [0.443-0.589], p = 0.671), both inferior to mesothelin. SOMAscan proteins correlated with inflammatory markers but not with asbestos exposure. Neither biomarker correlated with tumor volume. CONCLUSIONS: SOMAscan may prove useful as a future screening test for MPM in asbestos-exposed persons. Neither fibulin-3 nor SOMAscan should be used for diagnosis or pathway stratification.

Prevalence of histological abnormalities in hysterectomy specimens performed for prolapse. A systematic review and meta-analysis.

INTRODUCTION AND HYPOTHESIS: The practice of histopathological assessment of the uterus following hysterectomy for benign indications including pelvic organ prolapse (POP) surgery is common and often routine. While pathology is not anticipated, the finding of pathology requiring further action is always a concern, in particular CIN (cervical intraepithelial neoplasia) or cervical/uterine malignancy. We aimed to perform a systematic review to understand the prevalence of actionable uterine and cervical pathology in hysterectomy specimens performed for POP. METHODS: A literature search was performed in January 2020 of MEDLINE, Embase and CINAHL using the Healthcare Databases Advanced Search platform. Included studies reported CIN and/or uterine/cervical malignancy in histological assessment of hysterectomy specimens performed purely for POP. Meta-analysis of prevalence was performed using the MetaXL ( www.epigear.com ) add-in for Microsoft Excel. RESULTS: Six hundred seventy-seven records were identified, out of which 34 studies were eligible. Overall prevalence (95% confidence interval [CI]) of endometrial cancer in 33 studies was 0.004 (0.003-0.006), I2 = 41%, number needed to treat (NNT) 1:250. Total actionable uterine pathology was 0.005 (0.003-0.006) in 33 studies, I2 = 35%, NNT = 1:200. Overall prevalence of cervical cancer in 19 papers was 0.001 (0.000-0.002), I2 = 18%, NNT = 1:1000. In 16 studies the overall prevalence of CIN was 0.013 (0.001-0.033), I2 = 95%, NNT = 1:77. Prevalence of total actionable pathology was 0.013 (0.006-0.0023), I2 = 86%, NNT = 1:77. CONCLUSION: The risk of actionable pathology is low, but not negligible. The variation between populations is wide. The prevalence of finding such pathology supports the routine practice of sending all hysterectomy specimens performed for POP for histological assessment.

The effect of percutaneous tibial nerve stimulation (PTNS) on sexual function: a systematic review and meta-analysis.

INTRODUCTION: Percutaneous tibial nerve stimulation (PTNS) is now an established treatment of pelvic floor dysfunction such as overactive bladder, faecal incontinence or voiding dysfunction. Prevalence of female sexual dysfunction is high in this group. We aim to examine the effect of PTNS on sexual function in this patient group by systematically reviewing the literature and pooling the data in a meta-analysis. METHODS: The literature search was conducted using the MEDLINE, Embase and CINAHL databases. Initial results yielded 74 citations. From these, nine articles met our inclusion criteria. Two articles were doubly reported, leaving seven studies in the systematic review. Only four studies reported sufficient information to be included in our meta-analysis. RESULTS: Three studies were randomised controlled trials, and five were before-after studies. The number of participants in each study ranged from 11 to 220. Four out of seven studies reported a positive effect of PTNS on sexual function. In the meta-analysis of four studies there was a significant improvement in general sexual function with PTNS (p = 0.04, SMD -0.41, CI[-0.79, -0.03], I2 = 0%). In a subgroup analysis of the bowel domain of sexual function, there was a significant improvement with PTNS (p = 0.03, MD 17.7, CI [1.92, 33.47], I2 = 0%). CONCLUSION: We report a systematic review on the effect of PTNS on sexual function. Although the studies are of small size, the results are promising in terms of a positive effect of PTNS on sexual function, and we recommend further research in this area.

Sacral neuromodulation and sexual function: a systematic review and meta-analysis of the literature.

INTRODUCTION AND HYPOTHESIS: Sexual function is being increasingly recognized as an important patient-reported outcome. Sacral neuromodulation (SNM) is a treatment with an expanding list of indications. The effect of sacral neuromodulation on sexual function has been examined in a number of studies with variable results. In this review, we aim to systematically review the literature and pool the data if appropriate. METHODS: The literature search was conducted primarily on the Healthcare Databases Advanced Search (HDAS) platform using the Medline, EMBASE and CINHAL search engines. Of 196 initial citations, 17 articles met our predefined inclusion criteria. Thirteen studies reported enough information to be included in our meta-analysis. RevMan5 software was used for analysis. RESULTS: Eight of 17 studies reported a positive effect of SNM on sexual function. Pooled analysis of data from 11 studies involving 573 patients before SNM and 438 patients after SNM showed significant improvement in sexual function (SMD = -0.39; 95% CI: -0.58 to -0.19; p = 0.0001). The results remained significant in most subgroup analyses except in patients suffering from fecal incontinence. CONCLUSIONS: SNM in women with pelvic floor disorders, especially bladder dysfunction, seems to have a positive effect on sexual function. This needs to be verified in adequately powered primary research using sexual function as the primary outcome.

What are the experiences of seeking, receiving and providing FGM-related healthcare? Perspectives of health professionals and women/girls who have undergone FGM: protocol for a systematic review of qualitative evidence.

INTRODUCTION: Female genital mutilation (FGM) is an issue of global concern. High levels of migration mean that healthcare systems in higher-income western countries are increasingly being challenged to respond to the care needs of affected communities. Research has identified significant challenges in the provision of, and access to, FGM-related healthcare. There is a lack of confidence and competence among health professionals in providing appropriate care, suggesting an urgent need for evidence-based service development in this area. This study will involve two systematic reviews of qualitative evidence to explore the experiences, needs, barriers and facilitators to seeking and providing FGM-related healthcare in high-income (Organisation for Economic Cooperation and Development) countries, from the perspectives of: (1) women and girls who have undergone FGM and (2) health professionals. REVIEW METHODS: Twelve databases including MEDLINE, EMBASE, PsycINFO, ASSIA, Web of Science, ERIC, CINAHL, and POPLINE will be searched with no limits on publication year. Relevant grey literature will be identified from digital sources and professional networks.Two reviewers will independently screen, select and critically appraise the studies. Study quality will be assessed using the Joanna Briggs Institute Qualitative Assessment and Review Instrument appraisal tool. Findings will be extracted into NVivo software. Synthesis will involve inductive thematic analysis, including in-depth reading, line by line coding of the findings, development of descriptive themes and re-coding to higher level analytical themes. Confidence in the review findings will be assessed using the CERQual approach. Findings will be integrated into a comprehensive set of recommendations for research, policy and practice. DISSEMINATION: The syntheses will be reported as per the Enhancing Transparency in Reporting the Synthesis of Qualitative Research (ENTREQ) statement. Two reviews will be published in peer-reviewed journals and an integrated report disseminated at stakeholder engagement events. PROSPEROREGISTRATION NUMBER: CRD42015030001: 2015 and CRD42015030004: 2015.

Diagnostic and Prognostic Biomarkers in the Rational Assessment of Mesothelioma (DIAPHRAGM) study: protocol of a prospective, multicentre, observational study.

INTRODUCTION: Malignant pleural mesothelioma (MPM) is an asbestos-related cancer, which is difficult to diagnose. Thoracoscopy is frequently required but is not widely available. An accurate, non-invasive diagnostic biomarker would allow early specialist referral, limit diagnostic delays and maximise clinical trial access. Current markers offer insufficient sensitivity and are not routinely used. The SOMAmer proteomic classifier and fibulin-3 have recently demonstrated sensitivity and specificity exceeding 90% in retrospective studies. DIAPHRAGM (Diagnostic and Prognostic Biomarkers in the Rational Assessment of Mesothelioma) is a suitably powered, multicentre, prospective observational study designed to determine whether these markers provide clinically useful diagnostic and prognostic information. METHODS AND ANALYSIS: Serum and plasma (for SOMAscan and fibulin-3, respectively) will be collected at presentation, prior to pleural biopsy/pleurodesis, from 83 to 120 patients with MPM, at least 480 patients with non-MPM pleural disease and 109 asbestos-exposed controls. Final numbers of MPM/non-MPM cases will depend on the incidence of MPM in the study population (estimated at 13-20%). Identical sampling and storage protocols will be used in 22 recruiting centres and histological confirmation sought in all cases. Markers will be measured using the SOMAscan proteomic assay (SomaLogic) and a commercially available fibulin-3 ELISA (USCN Life Science). The SE in the estimated sensitivity and specificity will be <5% for each marker and their performance will be compared with serum mesothelin. Blood levels will be compared with paired pleural fluid levels and MPM tumour volume (using MRI) in a nested substudy. The prognostic value of each marker will be assessed and a large bioresource created. ETHICS AND DISSEMINATION: The study has been approved by the West of Scotland Research Ethics Committee (Ref: 13/WS/0240). A Trial Management Group meets on a monthly basis. Results will be published in peer-reviewed journals, presented at international meetings and disseminated to patient groups. TRIAL REGISTRATION NUMBER: ISRCTN10079972, Pre-results.

Randomized Trial of Labor Induction in Women 35 Years of Age or Older.

BACKGROUND: The risk of antepartum stillbirth at term is higher among women 35 years of age or older than among younger women. Labor induction may reduce the risk of stillbirth, but it also may increase the risk of cesarean delivery, which already is common in this older age group. METHODS: We conducted a randomized, controlled trial involving primigravid women who were 35 years of age or older. Women were randomly assigned to labor induction between 39 weeks 0 days and 39 weeks 6 days of gestation or to expectant management (i.e., waiting until the spontaneous onset of labor or until the development of a medical problem that mandated induction). The primary outcome was cesarean delivery. The trial was not designed or powered to assess the effects of labor induction on stillbirth. RESULTS: A total of 619 women underwent randomization. In an intention-to-treat analysis, there were no significant between-group differences in the percentage of women who underwent a cesarean section (98 of 304 women in the induction group [32%] and 103 of 314 women in the expectant-management group [33%]; relative risk, 0.99; 95% confidence interval [CI], 0.87 to 1.14) or in the percentage of women who had a vaginal delivery with the use of forceps or vacuum (115 of 304 women [38%] and 104 of 314 women [33%], respectively; relative risk, 1.30; 95% CI, 0.96 to 1.77). There were no maternal or infant deaths and no significant between-group differences in the women's experience of childbirth or in the frequency of adverse maternal or neonatal outcomes. CONCLUSIONS: Among women of advanced maternal age, induction of labor at 39 weeks of gestation, as compared with expectant management, had no significant effect on the rate of cesarean section and no adverse short-term effects on maternal or neonatal outcomes. (Funded by the Research for Patient Benefit Programme of the National Institute for Health Research; Current Controlled Trials number, ISRCTN11517275.).

Identification of a Selective G1-Phase Benzimidazolone Inhibitor by a Senescence-Targeted Virtual Screen Using Artificial Neural Networks.

Cellular senescence is a barrier to tumorigenesis in normal cells, and tumor cells undergo senescence responses to genotoxic stimuli, which is a potential target phenotype for cancer therapy. However, in this setting, mixed-mode responses are common with apoptosis the dominant effect. Hence, more selective senescence inducers are required. Here we report a machine learning-based in silico screen to identify potential senescence agonists. We built profiles of differentially affected biological process networks from expression data obtained under induced telomere dysfunction conditions in colorectal cancer cells and matched these to a panel of 17 protein targets with confirmatory screening data in PubChem. We trained a neural network using 3517 compounds identified as active or inactive against these targets. The resulting classification model was used to screen a virtual library of ~2M lead-like compounds. One hundred and forty-seven virtual hits were acquired for validation in growth inhibition and senescence-associated ß-galactosidase assays. Among the found hits, a benzimidazolone compound, CB-20903630, had low micromolar IC50 for growth inhibition of HCT116 cells and selectively induced senescence-associated ß-galactosidase activity in the entire treated cell population without cytotoxicity or apoptosis induction. Growth suppression was mediated by G1 blockade involving increased p21 expression and suppressed cyclin B1, CDK1, and CDC25C. In addition, the compound inhibited growth of multicellular spheroids and caused severe retardation of population kinetics in long-term treatments. Preliminary structure-activity and structure clustering analyses are reported, and expression analysis of CB-20903630 against other cell cycle suppressor compounds suggested a PI3K/AKT-inhibitor-like profile in normal cells, with different pathways affected in cancer cells.

An evaluation on the effectiveness of Web 2.0 Startpages (Netvibes & Pageflakes) within NHS libraries.

Carol McCormick was Learning Resources Advisor in the library at James Cook University Hospital, South Teesside when she completed her BSc (Hons) Librarianship (Work Based Learning) degree at Northumbria University. She gained a 1st Class Honours and is now Learning Resources Librarian. Carol's dissertation formed part of a wider action research project into the provision of current awareness services at James Cook University Hospital. This article reports on the evaluation which was conducted after a Web 2.0 Startpage, or portal, had been introduced to improve access to current awareness information for all staff within the Trust. It is the second article in the Dissertations into practice series to examine the use of web-based tools to improve access to information for NHS staff. AM.

Induction of labour versus expectant management for nulliparous women over 35 years of age: a multi-centre prospective, randomised controlled trial.

BACKGROUND: British women are increasingly delaying childbirth. The proportion giving birth over the age of 35 rose from 12% in 1996 to 20% in 2006. Women over this age are at a higher risk of perinatal death, and antepartum stillbirth accounts for 61% of all such deaths. Women over 40 years old have a similar stillbirth risk at 39 weeks as women who are between 25 and 29 years old have at 41 weeks.Many obstetricians respond to this by suggesting labour induction at term to forestall some of the risk. In a national survey of obstetricians 37% already induce women aged 40-44 years. A substantial minority of parents support such a policy, but others do not on the grounds that it might increase the risk of Caesarean section. However trials of induction in other high-risk scenarios have not shown any increase in Caesarean sections, rather the reverse. If induction for women over 35 did not increase Caesareans, or even reduced them, it would plausibly improve perinatal outcome and be an acceptable intervention. We therefore plan to perform a trial to test the effect of such an induction policy on Caesarean section rates.This trial is funded by the NHS Research for Patient Benefit (RfPB) Programme. DESIGN: The 35/39 trial is a multi-centre, prospective, randomised controlled trial. It is being run in twenty UK centres and we aim to recruit 630 nulliparous women (315 per group) aged over 35 years of age, over two years. Women will be randomly allocated to one of two groups: Induction of labour between 39°/7 and 396/7 weeks gestation. Expectant management i.e. awaiting spontaneous onset of labour unless a situation develops necessitating either induction of labour or Caesarean Section.The primary purpose of this trial is to establish what effect a policy of induction of labour at 39 weeks for nulliparous women of advanced maternal age has on the rate of Caesarean section deliveries. The secondary aim is to act as a pilot study for a trial to answer the question, does induction of labour in this group of women improve perinatal outcomes? Randomisation will occur at 36°/7-396/7 weeks gestation via a computerised randomisation programme at the Clinical Trials Unit, University of Nottingham. There will be no blinding to treatment allocation. DISCUSSION: The 35/39 trial is powered to detect an effect of induction of labour on the risk of caesarean section, it is underpowered to determine whether it improves perinatal outcome. The current study will also act as a pilot for a larger study to address this question. TRIAL REGISTRATION: ISRCTN11517275.

The effect of dacomitinib (PF-00299804) on CYP2D6 activity in healthy volunteers who are extensive or intermediate metabolizers.

PURPOSE: This study evaluated the effect of a single 45-mg dose of dacomitinib (PF-00299804), an irreversible small-molecule inhibitor of human epidermal growth factor receptors-1, -2, and -4, on CYP2D6 activity in healthy volunteers (HV) using dextromethorphan (DM), a selective CYP2D6 probe. METHODS: Fourteen male HVs were enrolled in this open-label, randomized, cross-over, single-dose study of DM alone or with dacomitinib. Each HV received both treatments separated by a 14-day washout period. The pharmacokinetics of DM, dextrorphan (DX; the major DM metabolite), dacomitinib and PF-05199265 (an active metabolite of dacomitinib) were calculated. RESULTS: When combined with dacomitinib, the ratio of adjusted geometric means (90% CI) of DM area under the concentration-time curve (AUC)(last) was 955% (90% CI: 560%, 1,630%) and maximum plasma concentration (C (max)) was 973% (90% CI: 590%, 1,606%), compared with DM alone. For dacomitinib plus DM, exposures were consistent with those in patients receiving single-dose dacomitinib. Terminal elimination half-life (t (1/2)) was 51.4 h. Mild and moderate treatment-related adverse events were reported. No HV withdrew from the study. CONCLUSIONS: Single-dose administration of dacomitinib plus DM was safe and well tolerated in HVs and resulted in a significant increase in systemic exposures of DM in extensive metabolizers. No effect was observed on the pharmacokinetics of dacomitinib. Drug-drug interaction may occur when dacomitinib is concomitantly administered with therapeutic agents metabolized by cytochrome P450 (CYP) 2D6. Administration of drugs which are highly dependent on CYP2D6 metabolism may require dose adjustment, or substitution with an alternative medication.

Phase I and pharmacodynamic trial of the DNA methyltransferase inhibitor decitabine and carboplatin in solid tumors.

PURPOSE: The DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine (decitabine) induces DNA demethylation and re-expression of epigenetically silenced genes, and increases carboplatin sensitivity of tumor xenograft models. We designed a clinical study to determine the feasibility of delivering a dose of decitabine, combined with carboplatin, that would be capable of producing equivalent biologic effects in patients with solid tumors. PATIENTS AND METHODS: In a two-stage design, 33 patients received escalating doses of decitabine administered as a 6-hour infusion on day 1 followed by carboplatin, area under the concentration-time curve (AUC) 5 (cohort 1) and AUC 6 (cohort 2), on day 8 of a 28-day cycle. Pharmacodynamic analyses included 5-methyl-2'-deoxycytidine levels, MAGE1A CpG island methylation, and fetal hemoglobin (HbF) expression. RESULTS: The major toxicity was myelosuppression. Dose limiting toxicities, prolonged grade 4 neutropenia (one patient), and sepsis and grade 3 anorexia/fatigue (one patient), were seen in two of four patients treated with decitabine 135 mg/m2 and carboplatin AUC 5. Dose limiting toxicity comprising neutropenic sepsis (one patient) and grade 3 fatigue (one patient) was seen in two of 10 patients treated at decitabine 90 mg/m2 and carboplatin AUC 6. Decitabine induced dose-dependent, reversible demethylation in peripheral-blood cells (PBCs) maximally at day 10. Furthermore, decitabine 90 mg/m2 induced demethylation of the MAGE1A CpG island in PBCs, buccal cells, and tumor biopsies, as well as elevation of HbF expression. CONCLUSION: Decitabine can be combined safely with carboplatin at a dose and schedule that causes epigenetic changes equivalent to or greater than that observed in mice with carboplatin-sensitized xenografts. The recommended dose/schedule for phase II trials is decitabine 90 mg/m2 (day 1) followed by carboplatin AUC 6 (day 8) every 28 days.

DNA methylation during mouse hemopoietic differentiation and radiation-induced leukemia.

OBJECTIVE: To examine DNA methylation in mouse hemopoiesis before and after in vivo exposure to a leukemogenic dose of x-rays, and address whether methylation levels are associated with the relative radiosensitivity of tissues in vivo. METHODS: The methylation status of control CBA/H and C57BL/6 mouse tissues before and after exposure to 3-Gy x-rays, and myeloid and lymphoid leukemias and lymphomas, was assessed by the direct analysis of the 5-methylcytosine (5-(Me)C) content of DNA, and by Southern blot analysis of genomic repeat sequences. RESULTS: The DNA 5-(Me)C content of bone marrow is 15% lower than spleen. Together with the analyses of stem (myeloid) and progenitor (lymphoid) leukemias and lymphomas, we found a trend of increasing methylation during hemopoietic differentiation. Exposure to x-rays induced greater cell death in the hypomethylated bone marrow (>80%) than spleen (50%) in vivo, supporting the observed correlation found between methylation status and radiosensitivity of other high-turnover hierarchical tissues. Furthermore, there was an 8% DNA 5-(Me)C content decrease in bone marrow after in vivo exposure to 3-Gy x-rays, but this was genotype dependent, being observed in AML-susceptible (CBA/H) but not AML-resistant (C57BL/6) inbred mice. CONCLUSION: Together these data suggest that methylation status may be related to the relative radiosensitivity of high-turnover hierarchical tissues such as bone marrow and that radiation-induced DNA hypomethylation has a role in radiation leukemogenesis.

Interactions of the DNA mismatch repair proteins MLH1 and MSH2 with c-MYC and MAX.

MSH2 and MLH1 have a central role in correcting mismatches in DNA occurring during DNA replication and have been implicated in the engagement of apoptosis induced by a number of cytotoxic anticancer agents. The function of MLH1 is not clearly defined, although it is required for mismatch repair (MMR) and engagement of apoptosis after certain types of DNA damage. In order to identify other partners of MLH1 that may be involved in signalling MMR or apoptosis, we used human MLH1 in yeast two-hybrid screens of normal human breast and ovarian cDNA libraries. As well as known partners of MLH1 such as PMS1, MLH3 and MBD4, we identified the carboxy terminus of the human c-MYC proto-oncogene as an interacting sequence. We demonstrate, both in vitro by yeast two-hybrid and GST-fusion pull-down experiments, as well as in vivo by coimmunoprecipitation from human tumour cell extracts, that MLH1 interacts with the c-MYC protein. We further demonstrate that the heterodimeric partner of c-MYC, MAX, interacts with a different MMR protein, MSH2, both in vitro and in vivo. Using an inducible c-MYC-ER fusion gene, we show that elevated c-MYC expression leads to an increased HGPRT mutation rate of Rat1 cells and an increase in the number of frameshift mutants at the HGPRT locus. The effect on HGPRT mutation rate is small (2-3-fold), but is consistent with deregulated c-MYC expression partially inhibiting MMR activity.