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2.
Epidemiol Infect ; 151: e189, 2023 Oct 31.
Article in English | MEDLINE | ID: mdl-37905583

ABSTRACT

Since the emergence of Omicron variant of SARS-CoV-2 in late 2021, a number of sub-lineages have arisen and circulated internationally. Little is known about the relative severity of Omicron sub-lineages BA.2.75, BA.4.6, and BQ.1. We undertook a case-control analysis to determine the clinical severity of these lineages relative to BA.5, using whole genome sequenced, PCR-confirmed infections, between 1 August 2022 and 27 November 2022, among those who presented to emergency care in England 14 days after and up to one day prior to the positive specimen. A total of 10,375 episodes were included in the analysis; of which, 5,207 (50.2%) were admitted to the hospital or died. Multivariable conditional regression analyses found no evidence of greater odds of hospital admission or death among those with BA.2.75 (odds ratio (OR) = 0.96, 95% confidence interval (CI): 0.84-1.09) and BA.4.6 (OR = 1.02, 95% CI: 0.88- 1.17) or BQ.1 (OR = 1.03, 95% CI: 0.94-1.13) compared to BA.5. Future lineages may not follow the same trend and there remains a need for continued surveillance of COVID-19 variants and their clinical outcomes to inform the public health response.


Subject(s)
COVID-19 , Emergency Medical Services , Humans , COVID-19/epidemiology , England/epidemiology , Hospitalization , Hospitals
3.
Epidemiol Infect ; 151: e169, 2023 09 20.
Article in English | MEDLINE | ID: mdl-37726109

ABSTRACT

Whole-genome sequencing (WGS) information has played a crucial role in the SARS-CoV-2 (COVID-19) pandemic by providing evidence about variants to inform public health policy. The purpose of this study was to assess the representativeness of sequenced cases compared with all COVID-19 cases in England, between March 2020 and August 2021, by demographic and socio-economic characteristics, to evaluate the representativeness and utility of these data in epidemiological analyses. To achieve this, polymerase chain reaction (PCR)-confirmed COVID-19 cases were extracted from the national laboratory system and linked with WGS data. During the study period, over 10% of COVID-19 cases in England had WGS data available for epidemiological analysis. With sequencing capacity increasing throughout the period, sequencing representativeness compared to all reported COVID-19 cases increased over time, allowing for valuable epidemiological analyses using demographic and socio-economic characteristics, particularly during periods with emerging novel SARS-CoV-2 variants. This study demonstrates the comprehensiveness of England's sequencing throughout the COVID-19 pandemic, rapidly detecting variants of concern, and enabling representative epidemiological analyses to inform policy.


Subject(s)
COVID-19 , Humans , COVID-19/epidemiology , SARS-CoV-2/genetics , Pandemics , England/epidemiology
4.
Vaccine ; 41(41): 5957-5964, 2023 09 22.
Article in English | MEDLINE | ID: mdl-37658001

ABSTRACT

OBJECTIVE: Countries routinely offering acellular pertussis vaccine, where long-term protection is not sustained, have the challenge of selecting an optimal schedule to minimise disease among young infants. We conducted a narrative systematic review and synthesis of information to evaluate different pertussis immunisation strategies at controlling pertussis disease, hospitalisation, deaths, and vaccine effectiveness among young infants. METHODS: We conducted a review of the literature on studies about the primary, booster, and/or maternal vaccination series and synthesised findings narratively. Countries offering the first three doses of vaccine within six-months of life and a booster on or before the second year or life were defined as accelerated primary and booster schedules, respectively. Countries offering primary and booster doses later were defined as extended primary and booster schedules. All search results were screened, and articles reviewed and reconciled, by two authors. The Risk of Bias in Non-randomised Studies of Intervention tool was used to evaluate the risk of bias. FINDINGS: A total of 98 studies were included in the analyses and the following recurring themes were described: timing of vaccination, vaccine coverage, waning immunity/vaccine effectiveness, direct and indirect effectiveness, switching from an accelerated to extended schedule, impact of changes in testing. The risk of bias was generally low to moderate for most studies. CONCLUSION: Comparing schedules is challenging and there was insufficient evidence to that one schedule was superior to another. Countries must select a schedule that maintains high vaccine coverage and reduced the risk of delaying the delivery vaccines to protect infants.


Subject(s)
Whooping Cough , Humans , Infant , Whooping Cough/prevention & control , Vaccination , Evidence Gaps , Family , Hospitalization
5.
Influenza Other Respir Viruses ; 17(5): e13150, 2023 05.
Article in English | MEDLINE | ID: mdl-37246147

ABSTRACT

There are concerns that sotrovimab has reduced efficacy at reducing hospitalisation risk against the BA.2 sub-lineage of the Omicron SARS-CoV-2 variant. We performed a retrospective cohort (n = 8850) study of individuals treated with sotrovimab in the community, with the objective of assessing whether there were any differences in risk of hospitalisation of BA.2 cases compared with BA.1. We estimated that the hazard ratio of hospital admission with a length of stay of 2 days or more was 1.17 for BA.2 compared with BA.1 (95%CI 0.74-1.86). These results suggest that the risk of hospital admission was similar between the two sub-lineages.


Subject(s)
COVID-19 , SARS-CoV-2 , Humans , Retrospective Studies , COVID-19/epidemiology , England/epidemiology
7.
Epidemiol Infect ; 151: e58, 2023 03 20.
Article in English | MEDLINE | ID: mdl-36938806

ABSTRACT

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant (B.1.1.529) rapidly replaced Delta (B.1.617.2) to become dominant in England. Our study assessed differences in transmission between Omicron and Delta using two independent data sources and methods. Omicron and Delta cases were identified through genomic sequencing, genotyping and S-gene target failure in England from 5-11 December 2021. Secondary attack rates for named contacts were calculated in household and non-household settings using contact tracing data, while household clustering was identified using national surveillance data. Logistic regression models were applied to control for factors associated with transmission for both methods. For contact tracing data, higher secondary attack rates for Omicron vs. Delta were identified in households (15.0% vs. 10.8%) and non-households (8.2% vs. 3.7%). For both variants, in household settings, onward transmission was reduced from cases and named contacts who had three doses of vaccine compared to two, but this effect was less pronounced for Omicron (adjusted risk ratio, aRR 0.78 and 0.88) than Delta (aRR 0.62 and 0.68). In non-household settings, a similar reduction was observed only in contacts who had three doses vs. two doses for both Delta (aRR 0.51) and Omicron (aRR 0.76). For national surveillance data, the risk of household clustering, was increased 3.5-fold for Omicron compared to Delta (aRR 3.54 (3.29-3.81)). Our study identified increased risk of onward transmission of Omicron, consistent with its successful global displacement of Delta. We identified a reduced effectiveness of vaccination in lowering risk of transmission, a likely contributor for the rapid propagation of Omicron.


Subject(s)
COVID-19 , SARS-CoV-2 , Humans , SARS-CoV-2/genetics , Cohort Studies , COVID-19/epidemiology , COVID-19/prevention & control , Vaccination , England/epidemiology
9.
Lancet ; 399(10332): 1303-1312, 2022 04 02.
Article in English | MEDLINE | ID: mdl-35305296

ABSTRACT

BACKGROUND: The omicron variant (B.1.1.529) of SARS-CoV-2 has demonstrated partial vaccine escape and high transmissibility, with early studies indicating lower severity of infection than that of the delta variant (B.1.617.2). We aimed to better characterise omicron severity relative to delta by assessing the relative risk of hospital attendance, hospital admission, or death in a large national cohort. METHODS: Individual-level data on laboratory-confirmed COVID-19 cases resident in England between Nov 29, 2021, and Jan 9, 2022, were linked to routine datasets on vaccination status, hospital attendance and admission, and mortality. The relative risk of hospital attendance or admission within 14 days, or death within 28 days after confirmed infection, was estimated using proportional hazards regression. Analyses were stratified by test date, 10-year age band, ethnicity, residential region, and vaccination status, and were further adjusted for sex, index of multiple deprivation decile, evidence of a previous infection, and year of age within each age band. A secondary analysis estimated variant-specific and vaccine-specific vaccine effectiveness and the intrinsic relative severity of omicron infection compared with delta (ie, the relative risk in unvaccinated cases). FINDINGS: The adjusted hazard ratio (HR) of hospital attendance (not necessarily resulting in admission) with omicron compared with delta was 0·56 (95% CI 0·54-0·58); for hospital admission and death, HR estimates were 0·41 (0·39-0·43) and 0·31 (0·26-0·37), respectively. Omicron versus delta HR estimates varied with age for all endpoints examined. The adjusted HR for hospital admission was 1·10 (0·85-1·42) in those younger than 10 years, decreasing to 0·25 (0·21-0·30) in 60-69-year-olds, and then increasing to 0·47 (0·40-0·56) in those aged at least 80 years. For both variants, past infection gave some protection against death both in vaccinated (HR 0·47 [0·32-0·68]) and unvaccinated (0·18 [0·06-0·57]) cases. In vaccinated cases, past infection offered no additional protection against hospital admission beyond that provided by vaccination (HR 0·96 [0·88-1·04]); however, for unvaccinated cases, past infection gave moderate protection (HR 0·55 [0·48-0·63]). Omicron versus delta HR estimates were lower for hospital admission (0·30 [0·28-0·32]) in unvaccinated cases than the corresponding HR estimated for all cases in the primary analysis. Booster vaccination with an mRNA vaccine was highly protective against hospitalisation and death in omicron cases (HR for hospital admission 8-11 weeks post-booster vs unvaccinated: 0·22 [0·20-0·24]), with the protection afforded after a booster not being affected by the vaccine used for doses 1 and 2. INTERPRETATION: The risk of severe outcomes following SARS-CoV-2 infection is substantially lower for omicron than for delta, with higher reductions for more severe endpoints and significant variation with age. Underlying the observed risks is a larger reduction in intrinsic severity (in unvaccinated individuals) counterbalanced by a reduction in vaccine effectiveness. Documented previous SARS-CoV-2 infection offered some protection against hospitalisation and high protection against death in unvaccinated individuals, but only offered additional protection in vaccinated individuals for the death endpoint. Booster vaccination with mRNA vaccines maintains over 70% protection against hospitalisation and death in breakthrough confirmed omicron infections. FUNDING: Medical Research Council, UK Research and Innovation, Department of Health and Social Care, National Institute for Health Research, Community Jameel, and Engineering and Physical Sciences Research Council.


Subject(s)
COVID-19 , SARS-CoV-2 , COVID-19/epidemiology , COVID-19/prevention & control , Cohort Studies , England/epidemiology , Hospitalization , Humans , Vaccines, Synthetic , mRNA Vaccines
10.
N Engl J Med ; 386(16): 1532-1546, 2022 04 21.
Article in English | MEDLINE | ID: mdl-35249272

ABSTRACT

BACKGROUND: A rapid increase in coronavirus disease 2019 (Covid-19) cases due to the omicron (B.1.1.529) variant of severe acute respiratory syndrome coronavirus 2 in highly vaccinated populations has aroused concerns about the effectiveness of current vaccines. METHODS: We used a test-negative case-control design to estimate vaccine effectiveness against symptomatic disease caused by the omicron and delta (B.1.617.2) variants in England. Vaccine effectiveness was calculated after primary immunization with two doses of BNT162b2 (Pfizer-BioNTech), ChAdOx1 nCoV-19 (AstraZeneca), or mRNA-1273 (Moderna) vaccine and after a booster dose of BNT162b2, ChAdOx1 nCoV-19, or mRNA-1273. RESULTS: Between November 27, 2021, and January 12, 2022, a total of 886,774 eligible persons infected with the omicron variant, 204,154 eligible persons infected with the delta variant, and 1,572,621 eligible test-negative controls were identified. At all time points investigated and for all combinations of primary course and booster vaccines, vaccine effectiveness against symptomatic disease was higher for the delta variant than for the omicron variant. No effect against the omicron variant was noted from 20 weeks after two ChAdOx1 nCoV-19 doses, whereas vaccine effectiveness after two BNT162b2 doses was 65.5% (95% confidence interval [CI], 63.9 to 67.0) at 2 to 4 weeks, dropping to 8.8% (95% CI, 7.0 to 10.5) at 25 or more weeks. Among ChAdOx1 nCoV-19 primary course recipients, vaccine effectiveness increased to 62.4% (95% CI, 61.8 to 63.0) at 2 to 4 weeks after a BNT162b2 booster before decreasing to 39.6% (95% CI, 38.0 to 41.1) at 10 or more weeks. Among BNT162b2 primary course recipients, vaccine effectiveness increased to 67.2% (95% CI, 66.5 to 67.8) at 2 to 4 weeks after a BNT162b2 booster before declining to 45.7% (95% CI, 44.7 to 46.7) at 10 or more weeks. Vaccine effectiveness after a ChAdOx1 nCoV-19 primary course increased to 70.1% (95% CI, 69.5 to 70.7) at 2 to 4 weeks after an mRNA-1273 booster and decreased to 60.9% (95% CI, 59.7 to 62.1) at 5 to 9 weeks. After a BNT162b2 primary course, the mRNA-1273 booster increased vaccine effectiveness to 73.9% (95% CI, 73.1 to 74.6) at 2 to 4 weeks; vaccine effectiveness fell to 64.4% (95% CI, 62.6 to 66.1) at 5 to 9 weeks. CONCLUSIONS: Primary immunization with two doses of ChAdOx1 nCoV-19 or BNT162b2 vaccine provided limited protection against symptomatic disease caused by the omicron variant. A BNT162b2 or mRNA-1273 booster after either the ChAdOx1 nCoV-19 or BNT162b2 primary course substantially increased protection, but that protection waned over time. (Funded by the U.K. Health Security Agency.).


Subject(s)
COVID-19 Vaccines , COVID-19 , Vaccine Efficacy , 2019-nCoV Vaccine mRNA-1273/therapeutic use , BNT162 Vaccine/therapeutic use , COVID-19/prevention & control , COVID-19 Vaccines/therapeutic use , Case-Control Studies , ChAdOx1 nCoV-19/therapeutic use , Humans , Immunization, Secondary/adverse effects , SARS-CoV-2/genetics
11.
J Infect Dis ; 226(5): 808-811, 2022 09 13.
Article in English | MEDLINE | ID: mdl-35184201

ABSTRACT

To investigate if the AY.4.2 sublineage of the SARS-CoV-2 delta variant is associated with hospitalization and mortality risks that differ from non-AY.4.2 delta risks, we performed a retrospective cohort study of sequencing-confirmed COVID-19 cases in England based on linkage of routine health care datasets. Using stratified Cox regression, we estimated adjusted hazard ratios (aHR) of hospital admission (aHR = 0.85; 95% confidence interval [CI], .77-.94), hospital admission or emergency care attendance (aHR = 0.87; 95% CI, .81-.94), and COVID-19 mortality (aHR = 0.85; 95% CI, .71-1.03). The results indicate that the risks of hospitalization and mortality are similar or lower for AY.4.2 compared to cases with other delta sublineages.


Subject(s)
COVID-19 , SARS-CoV-2 , Hospitalization , Humans , Retrospective Studies
12.
HIV Med ; 23(1): 90-102, 2022 01.
Article in English | MEDLINE | ID: mdl-34528739

ABSTRACT

OBJECTIVES: We describe COVID-19 mortality among people with and without HIV during the first wave of the pandemic in England. METHODS: National surveillance data on adults (aged ≥ 15 years) with diagnosed HIV resident in England were linked to national COVID-19 mortality surveillance data (2 March 2020-16 June 2020); HIV clinicians verified linked cases and provided information on the circumstances of death. We present COVID-19 mortality rates by HIV status, using negative binomial regression to assess the association between HIV and mortality, adjusting for gender, age and ethnicity. RESULTS: Overall, 99 people with HIV, including 61 of black ethnicity, died of/with COVID-19 (107/100 000) compared with 49 483 people without HIV (109/100 000). Compared to people without HIV, higher COVID-19 mortality rates were observed in people with HIV of black (188 vs. 122/100 000) and Asian (131 vs. 77.0/100 000) ethnicity, and in both younger (15-59 years: 58.3 vs. 10.2/100 000) and older (≥ 60 years: 434 vs. 355/100 000) people. After adjustment for demographic factors, people with HIV had a higher COVID-19 mortality risk than those without (2.18; 95% CI: 1.76-2.70). Most people with HIV who died of/with COVID-19 had suppressed HIV viraemia (91%) and at least one comorbidity reported to be associated with poor COVID-19 outcomes (87%). CONCLUSIONS: In the first wave of the pandemic in England, COVID-19 mortality among people with HIV was low, but was higher than in those without HIV, after controlling for demographic factors. This supports the strategy of prioritizing COVID-19 vaccination for people with HIV and strongly encouraging its uptake, especially in those of black and Asian ethnicity.


Subject(s)
COVID-19 , HIV Infections , Pandemics , Adolescent , Adult , COVID-19/mortality , England/epidemiology , Female , HIV Infections/diagnosis , HIV Infections/epidemiology , Humans , Male , Middle Aged , Young Adult
13.
Bone Jt Open ; 2(11): 951-957, 2021 Nov.
Article in English | MEDLINE | ID: mdl-34783253

ABSTRACT

AIMS: The aim of this study was to surveil whether the standard operating procedure created for the NHS Golden Jubilee sufficiently managed COVID-19 risk to allow safe resumption of elective orthopaedic surgery. METHODS: This was a prospective study of all elective orthopaedic patients within an elective unit running a green pathway at a COVID-19 light site. Rates of preoperative and 30-day postoperative COVID-19 symptoms or infection were examined for a period of 40 weeks. The unit resumed elective orthopaedic services on 29 June 2020 at a reduced capacity for a limited number of day-case procedures with strict patient selection criteria, increasing to full service on 29 August 2020 with no patient selection criteria. RESULTS: A total of 2,373 cases were planned in the 40-week study period. Surgery was cancelled in 59 cases, six (10.2%) of which were due to having a positive preoperative COVID-19 screening test result. Of the remaining 2,314, 996 (43%) were male and 1,318 (57%) were female. The median age was 67 years (interquartile range 59.2 to 74.6). The median American Society of Anesthesiologists grade was 2. Hip and knee arthroplasties accounted for the majority of the operations (76%). Six patients tested positive for COVID-19 preoperatively (0.25%) and 39 patients were tested for COVID-19 within 30 days after discharge, with only five patients testing positive (0.22%). CONCLUSION: Through strict application of a COVID-19 green pathway, elective orthopaedic surgery could be safely delivered to a large number of patients with no selection criteria. Cite this article: Bone Jt Open 2021;2(11):951-957.

14.
BMC Infect Dis ; 21(Suppl 2): 844, 2021 Sep 13.
Article in English | MEDLINE | ID: mdl-34517818

ABSTRACT

BACKGROUND: Uptake of HIV self-tests (HIVST) remains low in Europe. We conducted two separate surveys to understand facilitators and barriers to the use of HIVST in two European countries, as part of the EU INTEGRATE Joint Action. In both countries, HIV has been legal since 2016. In Lithuania, where HIVST sales have been low, the survey primarily assessed acceptability whilst in Italy, with better HIVST uptake, usability was the focus. METHODS: Participants were recruited through community HIV testing sites, and in Lithuania also through social media. In Lithuania, participants self-completed a survey on their testing history, and attitudes toward and experiences with self-testing. In Italy participants performed an HIVST (Mylan Autotest) while being observed by a community health worker (CHW). Both participants and CHW completed a self-administered survey evaluating the experience of the participant. RESULTS: In Lithuania, awareness of HIV self-testing (75%) was high among the 138 people who completed the survey. Privacy and confidentiality (70%) was the most common reason to use an HIVST whilst cost was reported as the main barrier by 60%, only 15% were willing to pay the current price. Almost half (42%) were concerned about doing the test incorrectly and 36% preferred that a trained person could discuss their result. Purchasing HIVST at a pharmacy (70%) or online (61%) was favoured and 68% would opt to simultaneously test for other infections. In Italy, 28 people who had never used an HIVST before were observed using one. 43% found the test easy to use but CHWs reported that 36% of participants failed at least one step. The quick result (68%) was the most common reason to use one again, yet the main concerns were the lack of counselling (50%) and reading result alone (32%). CONCLUSIONS: HIVST are acceptable and usable, however cost is a major barrier. Local and national strategies are needed to increase awareness of and access to HIVST and target HIVST campaigns toward key risk groups such as MSM. Meanwhile, steps can be taken to improve testing instructions and support for self-testers. Offering multiplex testing for other infections would also likely increase uptake.


Subject(s)
HIV Infections , Sexual and Gender Minorities , Europe , HIV Infections/diagnosis , HIV Infections/epidemiology , Homosexuality, Male , Humans , Lithuania , Male , Mass Screening
15.
HIV Med ; 22(10): 892-897, 2021 11.
Article in English | MEDLINE | ID: mdl-34323336

ABSTRACT

The 56 Dean Street combination prevention model, a strong engagement with the LGBTQI community and flexible services adapted to users' changing needs led to an 80% drop in HIV diagnoses in gay, bisexual and other men who have sex with men (GBMSM) from 2015 to 2017. We describe the service changes at 56 Dean Street since 2012 which resulted in an increase in the frequency of HIV testing, the introduction of pre-exposure prophylaxis, earlier HIV diagnosis and a shorter time to viral suppression in those living with HIV. This model could be adapted to deliver similar results in those settings of high HIV prevalence among GBMSM and where access to technological innovation in healthcare and engagement with the community can be achieved.


Subject(s)
HIV Infections , Pre-Exposure Prophylaxis , Sexual and Gender Minorities , Bisexuality , HIV Infections/drug therapy , Homosexuality, Male , Humans , Male , Pre-Exposure Prophylaxis/methods
16.
Euro Surveill ; 22(25)2017 Jun 22.
Article in English | MEDLINE | ID: mdl-28662762

ABSTRACT

Since October 2015 up to September 2016, HIV diagnoses fell by 32% compared with October 2014-September 2015 among men who have sex with men (MSM) attending selected London sexual health clinics. This coincided with high HIV testing volumes and rapid initiation of treatment on diagnosis. The fall was most apparent in new HIV testers. Intensified testing of high-risk populations, combined with immediately received anti-retroviral therapy and a pre-exposure prophylaxis (PrEP) programme, may make elimination of HIV achievable.


Subject(s)
HIV Infections/diagnosis , HIV Infections/prevention & control , Homosexuality, Male/statistics & numerical data , Mass Screening/trends , Pre-Exposure Prophylaxis , Anti-HIV Agents/therapeutic use , HIV Infections/drug therapy , Humans , London , Male , Population Surveillance , Sexual Behavior , Sexual Health , Sexual Partners
17.
Mol Hum Reprod ; 22(11): 745-755, 2016 11.
Article in English | MEDLINE | ID: mdl-27470502

ABSTRACT

STUDY QUESTION: Does the Irinotecan metabolite 7-ethyl-10-hydroxycamptothecan (SN38) damage the gonads of male and female prepubertal mice? SUMMARY ANSWER: The Irinotecan metabolite SN38 reduces germ cell numbers within the seminiferous tubules of mouse testes at concentrations that are relevant to cancer patients, while in contrast it has little if any effect on the female germ cell population. WHAT IS KNOWN ALREADY: Little is known about the role of the chemotherapeutic agent Irinotecan on female fertility, with only one article to date reporting menopausal symptoms in perimenopausal women treated with Irinotecan, while no data are available either on adult male fertility or on the impact of Irinotecan on the subsequent fertility of prepubertal cancer patients, female or male. STUDY DESIGN SIZE, DURATION: Male and female gonads were obtained from postnatal day 5 C57BL/6 mice and exposed in vitro to a range of concentrations of the Irinotecan metabolite SN38: 0.002, 0.01, 0.05, 0.1 or 1 µg ml-1 for the testis and 0.1, 1, 2.5 or 5 µg ml-1 for the ovary, with treated gonads compared to control gonads not exposed to SN38. SN38 was dissolved in 0.5% dimethyl sulfoxide, with controls exposed to the same concentration of diluent. The number of testis fragments used for each analysis ranged between 3 and 9 per treatment group, while the number of ovaries used for each analysis ranged between 4 and 12 per treatment group. PARTICIPANTS/MATERIALS, SETTING, METHODS: Neonatal mouse gonads were developed in vitro, with tissue analysed at the end of the 4-6 day culture period, following immunofluorescence or hematoxylin and eosin staining. Statistical analyses were performed using one-way ANOVA followed by Bonferroni post-hoc test for normally distributed data and Kruskal-Wallis test followed by Dunns post-test for non-parametric data. MAIN RESULTS AND THE ROLE OF CHANCE: Abnormal testis morphology was observed when tissues were exposed to SN38, with a smaller seminiferous tubule diameter at the highest concentration of SN38 (1 µg ml-1, p < 0.001 versus control) and increased number of Sertoli cell-only tubules at the two highest concentrations of SN38 (0.1 µg ml-1, p < 0.001; 1 µg ml-1, p < 0.0001, both versus control). Within seminiferous tubules, a dose response decrease was observed in both germ cell number (mouse vasa homologue (MVH)-positive cells) and in proliferating cell number (bromodeoxyuridine (BrdU)-positive cells), with significance reached at the two highest concentrations of SN38 (0.1 µg ml-1, p < 0.01 for both; 1 µg ml-1, p < 0.001-MVH, p < 0.01-BrdU; all versus control). No change was seen in protein expression of the apoptotic marker cleaved caspase 3. Double immunofluorescence showed that occasional proliferating germ cells were present in treated testes, even after exposure to the highest drug concentration. When prepubertal ovaries were treated with SN38, no effect was seen on germ cell number, apoptosis or cell proliferation, even after exposure to the highest drug concentrations. LIMITATIONS REASONS FOR CAUTION: As with any study using in vitro experiments with an experimental animal model, caution is required when extrapolating the present findings to humans. Differences between human and mouse spermatogonial development also need to be considered when assessing the effect of chemotherapeutic exposure. However, the prepubertal testes and ovaries used in the present studies contain germ cell populations that are representative of those found in prepubertal patients, and experimental tissues were exposed to drug concentrations within the range found in patient plasma. WIDER IMPLICATIONS OF THE FINDINGS: Our findings demonstrate that the prepubertal mouse ovary is relatively insensitive to exposure to the Irinotecan metabolite SN38, while it induces a marked dose-dependent sensitivity in the testicular germ cell population. The study identifies the importance of further investigation to identify the risk of infertility in young male cancer patients treated with Irinotecan. LARGE SCALE DATA: None. STUDY FUNDING AND COMPETING INTERESTS: Work supported by Medical Research Grant (MRC) grant G1002118 and Children with Cancer UK grant 15-198. The authors declare that there is no conflict of interest that could prejudice the impartiality of the present research.


Subject(s)
Camptothecin/analogs & derivatives , Germ Cells/drug effects , Ovary/cytology , Testis/cytology , Animals , Apoptosis/drug effects , Camptothecin/metabolism , Camptothecin/pharmacology , Cell Proliferation/drug effects , Female , Fluorescent Antibody Technique , In Vitro Techniques , Irinotecan , Male , Mice , Mice, Inbred C57BL , Oocytes/drug effects , Organ Culture Techniques , Spermatogonia/drug effects
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