A rare case of giant cell tumor of the anterior rib presenting as a breast mass.

Initial diagnostic ultrasound of a 22-year-old female patient presenting with a palpable breast mass revealed a suspicious mass initially thought to arise from the breast. However, follow-up diagnostic mammography was normal without evidence of the 5 cm mass seen on ultrasound, and pathology results from ultrasound-guided core needle biopsy raised suspicion for giant cell tumor, making chest wall origin of the mass more likely. Further CT and MRI imaging indeed revealed a locally invasive mass arising from the anterior fifth rib. The patient was treated with denosumab to decrease tumor burden before surgery, and subsequently underwent successful surgical resection of the tumor with mesh overlay and flap reconstruction of the chest wall defect. This case highlights the importance of keeping chest wall lesions in the differential for lesions presenting clinically as breast lesions. Despite the rarity of giant cell tumor of the anterior rib and its unusual presentation as a breast mass, appropriate diagnostic imaging work-up allowed for successful diagnosis and treatment in this case.

Seasonal trends in antidepressant prescribing, depression, anxiety and self-harm in adolescents and young adults: an open cohort study using English primary care data.

BACKGROUND: There is an increasing demand for mental health services for young people, which may vary across the year. OBJECTIVE: To determine whether there are seasonal patterns in primary care antidepressant prescribing and mental health issues in adolescents and young adults. METHODS: This cohort study used anonymised electronic health records from general practices in England contributing to QResearch. It included 5 081 263 males and females aged 14-18 (adolescents), 19-23 and 24-28 years between 2006 and 2019. The incidence rates per 1000 person-years and the incidence rate ratios (IRRs) were calculated for the first records of a selective serotonin reuptake inhibitor (SSRI) prescription, depression, anxiety and self-harm. The IRRs were adjusted for year, region, deprivation, ethnic group and number of working days. FINDINGS: There was an increase in SSRI prescribing, depression and anxiety incidence in male and female adolescents in the autumn months (September-November) that was not seen in older age groups. The IRRs for SSRI prescribing for adolescents peaked in November (females: 1.75, 95% CI 1.67 to 1.83, p<0.001; males: 1.72, 95% CI 1.61 to 1.84, p<0.001, vs in January) and for depression (females: 1.29, 95% CI 1.25 to 1.33, p<0.001; males: 1.29, 95% CI 1.23 to 1.35, p<0.001). Anxiety peaked in November for females aged 14-18 years (1.17, 95% CI 1.13 to 1.22, p<0.001) and in September for males (1.19, 95% CI 1.12 to 1.27, p<0.001). CONCLUSIONS: There were higher rates of antidepressant prescribing and consultations for depression and anxiety at the start of the school year among adolescents. CLINICAL IMPLICATIONS: Support around mental health issues from general practitioners and others should be focused during autumn.

Imaging findings of fibroid torsion in pregnancy: A case report.

When our patient presented emergently to labor and delivery at 18 weeks pregnant with severe right abdominal pain, the common diagnoses (such as appendicitis, cholecystitis, etc.) were on the top of the differential. However, US and MRI revealed a rarer cause of her pain, a pedunculated fibroid. The most important question then became whether this fibroid had torsed, which would require surgical intervention to prevent life-threatening sequelae. Unfortunately, presurgical imaging diagnosis of fibroid torsion in pregnancy is difficult. We offer a description of our patient's imaging findings, which align with other radiologic descriptions of fibroid torsion in pregnancy in the literature, to contribute to the radiologist's diagnostic confidence in this patient population.

Frequency and impact of medication reviews for people aged 65 years or above in UK primary care: an observational study using electronic health records.

BACKGROUND: Medication reviews in primary care provide an opportunity to review and discuss the safety and appropriateness of a person's medicines. However, there is limited evidence about access to and the impact of routine medication reviews for older adults in the general population, particularly in the UK. We aimed to quantify the proportion of people aged 65 years and over with a medication review recorded in 2019 and describe changes in the numbers and types of medicines prescribed following a review. METHODS: We used anonymised primary care electronic health records from the UK's Clinical Practice Research Datalink (CPRD GOLD) to define a population of people aged 65 years or over in 2019. We counted people with a medication review record in 2019 and used Cox regression to estimate associations between demographic characteristics, diagnoses, and prescribed medicines and having a medication review. We used linear regression to compare the number of medicines prescribed as repeat prescriptions in the three months before and after a medication review. Specifically, we compared the 'prescription count' - the maximum number of different medicines with overlapping prescriptions people had in each period. RESULTS: Of 591,726 people prescribed one or more medicines at baseline, 305,526 (51.6%) had a recorded medication review in 2019. Living in a care home (hazard ratio 1.51, 95% confidence interval 1.40-1.62), medication review in the previous year (1.83, 1.69-1.98), and baseline prescription count (e.g. 5-9 vs 1 medicine 1.41, 1.37-1.46) were strongly associated with having a medication review in 2019. Overall, the prescription count tended to increase after a review (mean change 0.13 medicines, 95% CI 0.12-0.14). CONCLUSIONS: Although medication reviews were commonly recorded for people aged 65 years or over, there was little change overall in the numbers and types of medicines prescribed following a review. This study did not examine whether the prescriptions were appropriate or other metrics, such as dose or medicine changes within the same class. However, by examining the impact of medication reviews before the introduction of structured medication review requirements in England in 2020, it provides a useful benchmark which these new reviews can be compared with.

Impact of the COVID-19 pandemic on incidence of tics in children and young people: a population-based cohort study.

Background: Since the onset of the coronavirus (COVID-19) pandemic, clinicians have reported an increase in presentations of sudden and new onset tics particularly affecting teenage girls. This population-based study aimed to describe and compare the incidence of tics in children and young people in primary care before and during the COVID-19 pandemic in England. Methods: We used information from the UK Clinical Practice Research Datalink (CPRD) Aurum dataset and included males and females aged 4-11 years and 12-18 years between Jan 1, 2015, and Dec 31, 2021. We grouped the pre-pandemic period (2015-2019) and presented the pandemic years (2020, 2021) separately. We described the characteristics of children and young people with a first record of a motor or vocal tic in each time period. Incidence rates of tics by age-sex groups in 2015-2019, 2020, and 2021 were calculated. Negative binomial regression models were used to calculate incidence rate ratios. Findings: We included 3,867,709 males and females aged 4-18 years. Over 14,734,062 person-years of follow-up, 11,245 people had a first tic record during the whole study period. The characteristics of people with tics differed over time, with the proportion of females aged 12-18 years and the proportion with mental health conditions including anxiety increasing during the pandemic. Tic incidence rates per 10,000 person-years were highest for 4-11-year-old males in all three time periods (13.4 [95% confidence interval 13.0-13.8] in 2015-2019; 13.2 [12.3-14.1] in 2020; 15.1 [14.1-16.1] in 2021) but increased markedly during the pandemic in 12-18-year-old females, from 2.5 (2.3-2.7) in 2015-2019, to 10.3 (9.5-11.3) in 2020 and 13.1 (12.1-14.1) in 2021. There were smaller increases in incidence rates in 12-18-year-old males (4.6 [4.4-4.9] in 2015-2019; 4.7 [4.1-5.3] in 2020; 6.2 [5.5-6.9] in 2021) and 4-11-year-old females (4.9 [4.7-5.2] in 2015-2019; 5.7 [5.1-6.4] in 2020; 7.6 [6.9-8.3] in 2021). Incidence rate ratios comparing 2020 and 2021 with 2015-2019 were highest in the 12-18-year-old female subgroup (4.2 [3.6-4.8] in 2020; 5.3 [4.7-6.0] in 2021). Interpretation: The incidence of tics in children and young people increased across all age and sex groups during the COVID-19 pandemic, with a differentially large effect in teenage girls (a greater than four-fold increase). Furthermore, in those with tic symptoms, proportions with mental health disorders including anxiety increased during the pandemic. Further research is required on the social and contextual factors underpinning this rise in onset of tics in teenage girls. Funding: National Institute for Health Research Nottingham Biomedical Research Centre.

The Great Mimicker: Cutaneous Metastatic Melanoma Presenting as a Non-resolving Pleural Effusion.

Although melanoma starts as a local disease, it can metastasize to other sites of the body including the lung, brain, liver, and intestines. However, pleural involvement is a rare presentation. Here, we present a case of a 57-year-old man with a history of stage IIA cutaneous melanoma, that relapsed 3 years after cutaneous resection, presenting with a non-resolving pleural effusion. Pleural fluid analysis was consistent with an exudative effusion, and pleural biopsy confirmed metastatic melanoma. The patient was treated with dual therapy of ipilimumab and nivolumab, as per National Comprehensive Cancer Network guidelines, with good response. Thus, we recommend having a high index of clinical suspicion for metastatic pleural melanoma when a patient with a history of cutaneous melanoma presents with a non-resolving pleural effusion.

Association between mirtazapine use and serious self-harm in people with depression: an active comparator cohort study using UK electronic health records.

BACKGROUND: Studies report an increased risk of self-harm or suicide in people prescribed mirtazapine compared with other antidepressants. OBJECTIVES: To compare the risk of serious self-harm in people prescribed mirtazapine versus other antidepressants as second-line treatments. DESIGN AND SETTING: Cohort study using anonymised English primary care electronic health records, hospital admission data and mortality data with study window 1 January 2005 to 30 November 2018. PARTICIPANTS: 24 516 people diagnosed with depression, aged 18-99 years, initially prescribed a selective serotonin reuptake inhibitor (SSRI) and then prescribed mirtazapine, a different SSRI, amitriptyline or venlafaxine. MAIN OUTCOME MEASURES: Hospitalisation or death due to deliberate self-harm. Age-sex standardised rates were calculated and survival analyses were performed using inverse probability of treatment weighting to account for baseline covariates. RESULTS: Standardised rates of serious self-harm ranged from 3.8/1000 person-years (amitriptyline) to 14.1/1000 person-years (mirtazapine). After weighting, the risk of serious self-harm did not differ significantly between the mirtazapine group and the SSRI or venlafaxine groups (HRs (95% CI) 1.18 (0.84 to 1.65) and 0.85 (0.51 to 1.41) respectively). The risk was significantly higher in the mirtazapine than the amitriptyline group (3.04 (1.36 to 6.79)) but was attenuated after adjusting for dose. CONCLUSIONS: There was no evidence for a difference in risk between mirtazapine and SSRIs or venlafaxine after accounting for baseline characteristics. The higher risk in the mirtazapine versus the amitriptyline group might reflect residual confounding if amitriptyline is avoided in people considered at risk of self-harm. CLINICAL IMPLICATIONS: Addressing baseline risk factors and careful monitoring might improve outcomes for people at risk of serious self-harm.

Findability of UK health datasets available for research: a mixed methods study.

OBJECTIVE: How health researchers find secondary data to analyse is unclear. We sought to describe the approaches that UK organisations take to help researchers find data and to assess the findability of health data that are available for research. METHODS: We surveyed established organisations about how they make data findable. We derived measures of findability based on the first element of the FAIR principles (Findable, Accessible, Interoperable, Reproducible). We applied these to 13 UK health datasets and measured their findability via two major internet search engines in 2018 and repeated in 2021. RESULTS: Among 12 survey respondents, 11 indicated that they made metadata publicly available. Respondents said internet presence was important for findability, but that this needed improvement. In 2018, 8 out of 13 datasets were listed in the top 100 search results of 10 searches repeated on both search engines, while the remaining 5 were found one click away from those search results. In 2021, this had reduced to seven datasets directly listed and one dataset one click away. In 2021, Google Dataset Search had become available, which listed 3 of the 13 datasets within the top 100 search results. DISCUSSION: Measuring findability via online search engines is one method for evaluating efforts to improve findability. Findability could perhaps be improved with catalogues that have greater inclusion of datasets, field-level metadata and persistent identifiers. CONCLUSION: UK organisations recognised the importance of the internet for finding data for research. However, health datasets available for research were no more findable in 2021 than in 2018.

The risk of all-cause and cause-specific mortality in people prescribed mirtazapine: an active comparator cohort study using electronic health records.

BACKGROUND: Studies have reported an increased risk of mortality among people prescribed mirtazapine compared to other antidepressants. The study aimed to compare all-cause and cause-specific mortality between adults prescribed mirtazapine or other second-line antidepressants. METHODS: This cohort study used English primary care electronic medical records, hospital admission records, and mortality data from the Clinical Practice Research Datalink (CPRD), for the period 01 January 2005 to 30 November 2018. It included people aged 18-99 years with depression first prescribed a selective serotonin reuptake inhibitor (SSRI) and then prescribed mirtazapine (5081), a different SSRI (15,032), amitriptyline (3905), or venlafaxine (1580). Follow-up was from starting to stopping the second antidepressant, with a 6-month wash-out window, censoring at the end of CPRD follow-up or 30 November 2018. Age-sex standardised rates of all-cause mortality and death due to circulatory system disease, cancer, or respiratory system disease were calculated. Survival analyses were performed, accounting for baseline characteristics using inverse probability of treatment weighting. RESULTS: The cohort contained 25,598 people (median age 41 years). The mirtazapine group had the highest standardised mortality rate, with an additional 7.8 (95% confidence interval (CI) 5.9-9.7) deaths/1000 person-years compared to the SSRI group. Within 2 years of follow-up, the risk of all-cause mortality was statistically significantly higher in the mirtazapine group than in the SSRI group (weighted hazard ratio (HR) 1.62, 95% CI 1.28-2.06). No significant difference was found between the mirtazapine group and the amitriptyline (HR 1.18, 95% CI 0.85-1.63) or venlafaxine (HR 1.11, 95% CI 0.60-2.05) groups. After 2 years, the risk was significantly higher in the mirtazapine group compared to the SSRI (HR 1.51, 95% CI 1.04-2.19), amitriptyline (HR 2.59, 95% CI 1.38-4.86), and venlafaxine (HR 2.35, 95% CI 1.02-5.44) groups. The risks of death due to cancer (HR 1.74, 95% CI 1.06-2.85) and respiratory system disease (HR 1.72, 95% CI 1.07-2.77) were significantly higher in the mirtazapine than in the SSRI group. CONCLUSIONS: Mortality was higher in people prescribed mirtazapine than people prescribed a second SSRI, possibly reflecting residual differences in other risk factors between the groups. Identifying these potential health risks when prescribing mirtazapine may help reduce the risk of mortality.

Cancer Patient Management during COVID-19 Pandemic: An Audit of a Single-Surgeon Unit in a COVID-Hotspot.

The report evaluates the effect of coronavirus disease (COVID-19) pandemic on breast cancer treatment and management at a single-surgeon cancer care unit in one of the hotspots of COVID-19 in India. In response to the pandemic, the adjustments were made in the clinical practice to accommodate social distancing. Patient consultations were done over phone call or in-clinic visit with prior appointment to reduce the risk of exposure to COVID-19. Total number of patients that were treated at the clinic and the essential surgeries performed during the pandemic phases are summarized in the report. The methodology adopted here for care and management of the cancer patients can serve as a guiding principle for cancer care units in the country.

Finding a Balance in the Vaginal Microbiome: How Do We Treat and Prevent the Occurrence of Bacterial Vaginosis?

Bacterial vaginosis (BV) has been reported in one-third of women worldwide at different life stages, due to the complex balance in the ecology of the vaginal microbiota. It is a common cause of abnormal vaginal discharge and is associated with other health issues. Since the first description of anaerobic microbes associated with BV like Gardnerella vaginalis in the 1950s, researchers have stepped up the game by incorporating advanced molecular tools to monitor and evaluate the extent of dysbiosis within the vaginal microbiome, particularly on how specific microbial population changes compared to a healthy state. Moreover, treatment failure and BV recurrence rate remain high despite the standard antibiotic treatment. Consequently, researchers have been probing into alternative or adjunct treatments, including probiotics or even vaginal microbiota transplants, to ensure successful treatment outcomes and reduce the colonization by pathogenic microbes of the female reproductive tract. The current review summarizes the latest findings in probiotics use for BV and explores the potential of vaginal microbiota transplants in restoring vaginal health.

Secondary care specialist visits made by children and young people prescribed antidepressants in primary care: a descriptive study using the QResearch database.

BACKGROUND: Antidepressants may be used to manage a number of conditions in children and young people including depression, anxiety, and obsessive-compulsive disorder. UK guidelines for the treatment of depression in children and young people recommend that antidepressants should only be initiated following assessment and diagnosis by a child and adolescent psychiatrist. The aim of this study was to summarise visits to mental health specialists and indications recorded around the time of antidepressant initiation in children and young people in UK primary care. METHODS: The study used linked English primary care electronic health records and Hospital Episode Statistics secondary care data. The study included 5-17-year-olds first prescribed antidepressants between January 2006 and December 2017. Records of visits to paediatric or psychiatric specialists and potential indications (from a pre-specified list) were extracted. Events were counted if recorded less than 12 months before or 6 months after the first antidepressant prescription. Results were stratified by first antidepressant type (all, selective serotonin reuptake inhibitors (SSRIs), tricyclic and related antidepressants) and by age group (5-11 years, 12-17 years). RESULTS: In total, 33,031 5-17-year-olds were included. Of these, 12,149 (37%) had a record of visiting a paediatrician or a psychiatric specialist in the specified time window. The majority of recorded visits (7154, 22%) were to paediatricians. Of those prescribed SSRIs, 5463/22,130 (25%) had a record of visiting a child and adolescent psychiatrist. Overall, 17,972 (54%) patients had a record of at least one of the pre-specified indications. Depression was the most frequently recorded indication (12,501, 38%), followed by anxiety (4155, 13%). CONCLUSIONS: The results suggest many children and young people are being prescribed antidepressants without the recommended involvement of a relevant specialist. These findings may justify both greater training for GPs in child and adolescent mental health and greater access to specialist care and non-pharmacological treatments. Further research is needed to explore factors that influence how and why GPs prescribe antidepressants to children and young people and the real-world practice barriers to adherence to clinical guidelines.

Exposure measurement error when assessing current glucocorticoid use using UK primary care electronic prescription data.

PURPOSE: To quantify misclassification in glucocorticoid (GC) exposure defined using UK primary care prescription data. METHODS: A cross-sectional study including patients with rheumatoid arthritis prescribed oral GCs in the past 2 years. Glucocorticoid exposure based on electronic prescription records was compared with participant-reported GC use captured using a paper diary. Prescription data (containing information about prescriptions issued but no dispensing information) was provided by the Clinical Practice Research Datalink. The following variables were defined: current use and dose of oral GCs and if (and when) participants had received a GC injection. For oral GCs, self-reported use was taken to represent "true" exposure. A dataset representing a hypothetical population was generated to assess the impact of the misclassification found for current use. RESULTS: A total of 67 of 78 study participants (86%) were correctly classified as currently on/off oral GCs; 32/38 (84.2%) participants reporting current GC use and 35/40 (87.5%) participants not reporting current use were correctly classified. Estimated values of current dose were imprecise (correlation coefficient 0.46). Concordance between reported and prescribed GC injections was poor (kappa statistic 0.14). Misclassification bias was demonstrated in the hypothetical population: For "true" relative risks of 1.5, 4, and 9, the "observed" relative risks were 1.33, 2.48, and 3.58, respectively. CONCLUSIONS: Misclassification of current use of oral GCs was low but sufficient to lead to significant bias. Researchers should take care to assess the likely impact of exposure misclassification on their analyses.

Low salivary cortisol levels in patients with rheumatoid arthritis exposed to oral glucocorticoids: a cross-sectional study set within UK electronic health records.

BACKGROUND: Glucocorticoids (GCs) suppress endogenous cortisol levels which can lead to adrenal insufficiency (AI). The frequency of GC-induced AI remains unclear. In this cross-sectional study, low morning salivary cortisol (MSC) levels were used as a measure of adrenal function. The study aim was to investigate the prevalence of low MSC in patients with rheumatoid arthritis (RA) currently and formerly exposed to oral GCs, and the association with potential risk factors. METHODS: Sample collection was nested within UK primary care electronic health records (from the Clinical Practice Research Datalink). Participants were patients with RA with at least one prescription for oral GCs in the past 2 years. Self-reported oral GC use was used to define current use and current dose; prescription data were used to define exposure duration. MSC was determined from saliva samples; 5 nmol/L was the cut-off for low MSC. The prevalence of low MSC was estimated, and logistic regression was used to assess the association with potential risk factors. RESULTS: 66% of 38 current and 11 % of 38 former GC users had low MSC. Among former users with low MSC, the longest time since GC withdrawal was 6 months. Current GC dose, age and RA duration were significantly associated with increased risk of low MSC. CONCLUSION: The prevalence of low MSC among current GC users is high, and MSC levels may remain suppressed for several months after GC withdrawal. Clinicians should therefore consider the risk of suppressed cortisol and remain vigilant for symptoms of AI following GC withdrawal.

Assumptions made when preparing drug exposure data for analysis have an impact on results: An unreported step in pharmacoepidemiology studies.

PURPOSE: Real-world data for observational research commonly require formatting and cleaning prior to analysis. Data preparation steps are rarely reported adequately and are likely to vary between research groups. Variation in methodology could potentially affect study outcomes. This study aimed to develop a framework to define and document drug data preparation and to examine the impact of different assumptions on results. METHODS: An algorithm for processing prescription data was developed and tested using data from the Clinical Practice Research Datalink (CPRD). The impact of varying assumptions was examined by estimating the association between 2 exemplar medications (oral hypoglycaemic drugs and glucocorticoids) and cardiovascular events after preparing multiple datasets derived from the same source prescription data. Each dataset was analysed using Cox proportional hazards modelling. RESULTS: The algorithm included 10 decision nodes and 54 possible unique assumptions. Over 11 000 possible pathways through the algorithm were identified. In both exemplar studies, similar hazard ratios and standard errors were found for the majority of pathways; however, certain assumptions had a greater influence on results. For example, in the hypoglycaemic analysis, choosing a different variable to define prescription end date altered the hazard ratios (95% confidence intervals) from 1.77 (1.56-2.00) to 2.83 (1.59-5.04). CONCLUSIONS: The framework offers a transparent and efficient way to perform and report drug data preparation steps. Assumptions made during data preparation can impact the results of analyses. Improving transparency regarding drug data preparation would increase the repeatability, reproducibility, and comparability of published results.

Supplementing electronic health records through sample collection and patient diaries: A study set within a primary care research database.

PURPOSE: To describe a novel observational study that supplemented primary care electronic health record (EHR) data with sample collection and patient diaries. METHODS: The study was set in primary care in England. A list of 3974 potentially eligible patients was compiled using data from the Clinical Practice Research Datalink. Interested general practices opted into the study then confirmed patient suitability and sent out postal invitations. Participants completed a drug-use diary and provided saliva samples to the research team to combine with EHR data. RESULTS: Of 252 practices contacted to participate, 66 (26%) mailed invitations to patients. Of the 3974 potentially eligible patients, 859 (22%) were at participating practices, and 526 (13%) were sent invitations. Of those invited, 117 (22%) consented to participate of whom 86 (74%) completed the study. CONCLUSIONS: We have confirmed the feasibility of supplementing EHR with data collected directly from patients. Although the present study successfully collected essential data from patients, it also underlined the requirement for improved engagement with both patients and general practitioners to support similar studies.

Risks of smoking and benefits of smoking cessation on hospitalisations for cardiovascular events and respiratory infection in patients with rheumatoid arthritis: a retrospective cohort study using the Clinical Practice Research Datalink.

OBJECTIVES: To investigate the associations between smoking status, smoking cessation and hospitalisations for cardiovascular events (CVE) and respiratory tract infections (RTI) in an inception cohort of patients with rheumatoid arthritis (RA). METHODS: The study was set within UK primary care electronic health records (the Clinical Practice Research Datalink) linked to hospital inpatient data (Hospital Episode Statistics). Patients with RA were followed from diagnosis to hospitalisation with a record of CVE or RTI, leaving their general practice, death, or 10 January 2012, whichever was earliest. Smoking status (never, current, former) was defined using primary care data and could vary over time. Survival analysis was performed using Cox regression (first event) and conditional risk set models (multiple RTIs). RESULTS: 5677 patients were included in the cohort: 68% female, median age 61 years. The age-adjusted and sex-adjusted risks of hospitalisation for CVE or RTI were more than twice as high in current vs never smokers (CVE HR (95% CI) 2.19 (1.44 to 3.31); RTI 2.18 (1.71 to 2.78)). The risks for both outcomes were significantly higher in current compared with former smokers (CVE 1.51 (1.04 to 2.19), RTI 1.29 (1.04 to 1.61)). For each additional year of smoking cessation, the risk of first CVE and RTI hospitalisation fell significantly, approximately 25% and 15% respectively in the adjusted models. CONCLUSIONS: Patients with RA who smoke have an increased risk of hospitalisation with CVE or RTI compared with never and former smokers. The risk decreases for each additional year of smoking cessation. Patients with RA who smoke should be advised to stop smoking.

DNA mutagenic activity and capacity for HIV-1 restriction of the cytidine deaminase APOBEC3G depend on whether DNA or RNA binds to tyrosine 315.

APOBEC3G (A3G) belongs to the AID/APOBEC protein family of cytidine deaminases (CDA) that bind to nucleic acids. A3G mutates the HIV genome by deamination of dC to dU, leading to accumulation of virus-inactivating mutations. Binding to cellular RNAs inhibits A3G binding to substrate single-stranded (ss) DNA and CDA activity. Bulk RNA and substrate ssDNA bind to the same three A3G tryptic peptides (amino acids 181-194, 314-320, and 345-374) that form parts of a continuously exposed protein surface extending from the catalytic domain in the C terminus of A3G to its N terminus. We show here that the A3G tyrosines 181 and 315 directly cross-linked ssDNA. Binding experiments showed that a Y315A mutation alone significantly reduced A3G binding to both ssDNA and RNA, whereas Y181A and Y182A mutations only moderately affected A3G nucleic acid binding. Consistent with these findings, the Y315A mutant exhibited little to no deaminase activity in an Escherichia coli DNA mutator reporter, whereas Y181A and Y182A mutants retained ∼50% of wild-type A3G activity. The Y315A mutant also showed a markedly reduced ability to assemble into viral particles and had reduced antiviral activity. In uninfected cells, the impaired RNA-binding capacity of Y315A was evident by a shift of A3G from high-molecular-mass ribonucleoprotein complexes to low-molecular-mass complexes. We conclude that Tyr-315 is essential for coordinating ssDNA interaction with or entry to the deaminase domain and hypothesize that RNA bound to Tyr-315 may be sufficient to competitively inhibit ssDNA deaminase-dependent antiviral activity.

Systemic glucocorticoid therapy and adrenal insufficiency in adults: A systematic review.

OBJECTIVES: The aim of this systematic literature review was to summarize the current knowledge regarding the prevalence of, time to recovery from, and influence of glucocorticoid dose and duration on glucocorticoid-induced adrenal insufficiency (AI). METHODS: Eligible studies were original research articles, which included adult patients with an indication for glucocorticoids and measured adrenal function following exposure to systemic glucocorticoids. Searches were performed in Web of Science and MEDLINE, with further articles identified from reference lists. Screening was performed in duplicate. Data were extracted for each group of glucocorticoid-exposed patients within eligible studies. The reported proportion of patients with AI was summarized as median and inter-quartile range. Results were then stratified by daily dose, cumulative dose, duration of exposure and time since last glucocorticoid use. The risk of bias within and across studies was considered: for randomised controlled trials risk of bias was assessed using the tool developed by the Cochrane Collaboration. RESULTS: Overall, 73 eligible studies were identified out of 673 screened. The percentage of patients with AI ranged from 0% to 100% with a median (IQR) = 37.4% (13-63%). Studies were small-median (IQR) group size 16 (9-38)-and heterogeneous in methodology. AI persisted in 15% of patients retested 3 years after glucocorticoid withdrawal. Results remained widely distributed following stratification. AI was demonstrated at <5mg prednisolone equivalent dose/day, <4 weeks of exposure, cumulative dose <0.5g, and following tapered withdrawal. CONCLUSIONS: The heterogeneity of studies and variability in results make it difficult to answer the research questions with confidence based on the current literature. There is evidence of AI following low doses and short durations of glucocorticoids. Hence, clinicians should be vigilant for adrenal insufficiency at all degrees of glucocorticoid exposure.