Classification of nucleic acid amplification on ISFET arrays using spectrogram-based neural networks

The COVID-19 pandemic has highlighted a significant research gap in the field of molecular diagnostics. This has brought forth the need for AI-based edge solutions that can provide quick diagnostic results whilst maintaining data privacy, security and high standards of sensitivity and specificity. This paper presents a novel proof-of-concept method to detect nucleic acid amplification using ISFET sensors and deep learning. This enables the detection of DNA and RNA on a low-cost and portable lab-on-chip platform for identifying infectious diseases and cancer biomarkers. We show that by using spectrograms to transform the signal to the time-frequency domain, image processing techniques can be applied to achieve the reliable classification of the detected chemical signals. Transformation to spectrograms is beneficial as it makes the data compatible with 2D convolutional neural networks and helps gain significant performance improvement over neural networks trained on the time domain data. The trained network achieves an accuracy of 84% with a size of 30kB making it suitable for deployment on edge devices. This facilitates a new wave of intelligent lab-on-chip platforms that combine microfluidics, CMOS-based chemical sensing arrays and AI-based edge solutions for more intelligent and rapid molecular diagnostics.

Strengthening open disclosure after incidents in maternity care: a realist synthesis of international research evidence

BACKGROUND

Open Disclosure (OD) is open and timely communication about harmful events arising from health care with those affected. It is an entitlement of service-users and an aspect of their recovery, as well as an important dimension of service safety improvement. Recently, OD in maternity care in the English National Health Service has become a pressing public issue, with policymakers promoting multiple interventions to manage the financial and reputational costs of communication failures. There is limited research to understand how OD works and its effects in different contexts.

METHODS

Realist literature screening, data extraction, and retroductive theorisation involving two advisory stakeholder groups. Data relevant to families, clinicians, and services were mapped to theorise the relationships between contexts, mechanisms, and outcomes. From these maps, key aspects for successful OD were identified.

RESULTS

After realist quality appraisal, 38 documents were included in the synthesis (22 academic, 2 training guidance, and 14 policy report). 135 explanatory accounts were identified from the included documents (with n = 41 relevant to families; n = 37 relevant to staff; and n = 37 relevant to services). These were theorised as five key mechanism sets: (a) meaningful acknowledgement of harm, (b) opportunity for family involvement in reviews and investigations, (c) possibilities for families and staff to make sense of what happened, (d) specialist skills and psychological safety of clinicians, and (e) families and staff knowing that improvements are happening. Three key contextual factors were identified: (a) the configuration of the incident (how and when identified and classified as more or less severe); (b) national or state drivers, such as polices, regulations, and schemes, designed to promote OD; and (c) the organisational context within which these these drivers are recieived and negotiated.

CONCLUSIONS

This is the first review to theorise how OD works, for whom, in what circumstances, and why. We identify and examine from the secondary data the five key mechanisms for successful OD and the three contextual factors that influence this. The next study stage will use interview and ethnographic data to test, deepen, or overturn our five hypothesised programme theories to explain what is required to strengthen OD in maternity services.

Investigation of the critical factors required to improve the disclosure and discussion of harm with affected women and families: a study protocol for a qualitative, realist study in NHS maternity services (the DISCERN study)

Patients and families are entitled to an open disclosure and discussion of healthcare incidents affecting them. This reduces distress and contributes to learning for safety improvement. Complex barriers prevent effective disclosure and continue in the English NHS, despite a legal duty of candour. NHS maternity services are the focus of significant efforts to improve this. There is limited understanding of how, and to what effect, they are achieving this. METHODS AND ANALYSIS: A 27-month, three-phased realist evaluation identifying the critical factors contributing to improvements in the disclosure and discussion of incidents with affected families. The evaluation asks 'what works, for whom, in what circumstances, in why respects and why?'.Phase 1: establish working hypotheses of key factors and outcomes of interventions improving disclosure and discussion, by realist literature review and in-depth realist interviews with key stakeholders (n=approximately 20]Phase 2: refine or overturn hypotheses, by ethnographic case-study analysis using triangulated qualitative methods (non-participant observation, interviews (n=12) and documentary analysis) in up to 4 purposively sampled NHS trusts.Phase 3: consider hypotheses and design outputs during seven interpretive forums. ETHICS AND DISSEMINATION: Phase 1 study approval by King's College London's Ethics Panel (BDMRESC 22033) and National Research Ethical Approval for Phases 2-3 (IRASID:262197) (CAG:20/CAG/0121) (REC:20/LO/1152). Study sponsorship by King's College London (HS&DR 17/99/85).Findings to be disseminated through tailored management briefings; clinician and family guidance (written and video); lay summaries, academic papers, and report with outputs tailored to maximise academic and societal impact. Views of women/family groups are represented throughout.

Technologies for Size-Based Analysis of Circulating Cell-Free DNA: Limitations and Clinical Implementation

Prostate cancer is the second most common malignancy in men worldwide, and incidence is likely to rise in the next decade. The current screening options have limitations and have been shown to result in over-treatment of clinically insignificant disease. New biomarkers and technologies to detect them are therefore needed to better diagnose and stratify patients in primary care. Circulating cell-free DNA (ccfDNA) has gained interest as a potential minimally invasive biomarker, detectable in many bodily fluids (such as blood, urine, and cerebral spinal fluid) and reflecting the mutational landscape in tumors. More recently, the size distribution of ccfDNA fragments has also gained interest as a specific biomarker, where differences in size distribution have been observed between healthy volunteers and cancer patients, resulting in the new field of fragmentomics. Analysis of ccfDNA sizes provides avenues for alternative analytical technologies but commercial options are currently limited. Most focus on mutation detection and are subject to several biases that may affect size distribution. Here, we discuss the available technologies and identify major issues and considerations that may affect their implementation as a clinically useful test based on ccfDNA size profiling.

'This is time we'll never get back': a qualitative study of mothers' experiences of care associated with neonatal death

AIMS

To explore the perceptions and experience of women whose baby died in the neonatal period about their care in the perinatal period, on delivery suite, in the neonatal unit and afterwards, expressed in their own words.

DESIGN

Secondary analysis of the Listening to Parents study, using thematic analysis based on the open text responses from a postal survey of parents whose baby died in the neonatal period in England. Women were asked about care during the pregnancy, labour and birth, around the time the baby died and about neonatal care. Women whose pregnancy was terminated for fetal abnormality were excluded from this analysis.

RESULTS

Completed questionnaires were received from 249 mothers of whom most (78%) responded with open text. Overarching themes identified were 'the importance of proximity', 'recognition of role and identity as a parent' and 'the experience of care' and subthemes included 'hours and moments', 'barriers to contact', ' being able to parent, even for a short time', 'missed opportunities', 'being heard' and 'sensitive and responsive care'.

CONCLUSION

The findings identify what is most important for mothers in experiencing the life and death of a baby as a newborn. Physical contact with the baby was paramount, as was being treated as a mother and a parent and being able to function as such. The way in which healthcare staff behaved and how their babies were cared for was critical to how mothers felt supported and enabled at this time. If all women whose babies die in the neonatal period after birth are to receive the responsive care they need, greater understanding of the primary need for closeness and proximity, for active recognition of their parental role and staff awareness of the limited time window available is essential.

Parents' Active Role and ENgagement in The review of their Stillbirth/perinatal death 2 (PARENTS 2) study: a mixed-methods study of implementation

OBJECTIVE

When a formal review of care takes places after the death of a baby, parents are largely unaware it takes place and are often not meaningfully involved in the review process. Parent engagement in the process is likely to be essential for a successful review and to improve patient safety. This study aimed to evaluate an intervention process of parental engagement in perinatal mortality review (PNMR) and to identify barriers and facilitators to its implementation.

DESIGN

Mixed-methods study of parents' engagement in PNMR.

SETTING

Single tertiary maternity unit in the UK.

PARTICIPANTS

Bereaved parents and healthcare professionals (HCPs).

INTERVENTIONS

Parent engagement in the PNMR (intervention) was based on principles derived through national consensus and qualitative research with parents, HCPs and stakeholders in the UK.

OUTCOMES

Recruitment rates, bereaved parents and HCPs' perceptions.

RESULTS

Eighty-one per cent of bereaved parents approached (13/16) agreed to participate in the study. Two focus groups with bereaved parents (n=11) and HCP (n=7) were carried out postimplementation to investigate their perceptions of the process.Overarching findings were improved dialogue and continuity of care with parents, and improvements in the PNMR process and patient safety. Bereaved parents agreed that engagement in the PNMR process was invaluable and helped them in their grieving. HCP perceived that parent involvement improved the review process and lessons learnt from the deaths; information to understand the impact of aspects of care on the baby's death were often only found in the parents' recollections.

CONCLUSIONS

Parental engagement in the PNMR process is achievable and useful for parents and HCP alike, and critically can improve patient safety and future care for mothers and babies. To learn and prevent perinatal deaths effectively, all hospitals should give parents the option to engage with the review of their baby's death.

Did you see what I saw?: Comparing attentional synchrony during 360° video viewing in head mounted display and tablets

Advances in head mounted displays (HMDs) have increased the interest in cinematic virtual reality as an art form. However, the freedom of a viewer in 360 video presents challenges in ensuring that audiences do not inadvertently miss important events and locations. We examined whether the high level of immersion provided by HMDs encourages participants to synchronize their attention during viewing. Sixty-four participants watched the 360° documentary Clouds Over Sidra (VRSE.works, 2015) using either an HMD or via a flat screen tablet display. We used intersubject correlation (ISC) analysis to measure attentional synchrony over the course of the video and to examine whether spatial and temporal factors led to different amounts of correlation both within and between groups. We found significantly greater ISC for the HMD compared to the tablet group. This effect was greatest for scenes with a unidirectional focus and at the start of scenes. We discuss our results in terms of the visual properties and the motor affordances of HMDs versus tablets. Our results show the value of HMDs in increasing attentional synchrony and may provide producers of 360° content insight in how to encourage or discourage synchronization of viewing direction. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Parents' experiences of care following the loss of a baby at the margins between miscarriage, stillbirth and neonatal death: a UK qualitative study

OBJECTIVE

To explore the healthcare experiences of parents whose baby died either before, during or shortly after birth between 20⁺⁰ and 23⁺⁶  weeks of gestation in order to identify practical ways to improve healthcare provision.

DESIGN

Qualitative interview study.

SETTING

England through two parent support organisations and four NHS Trusts.

SAMPLE

A purposive sample of parents.

METHODS

Thematic analysis of semi-structured in-depth narrative interviews.

MAIN OUTCOME MEASURES

Parents' healthcare experiences.

RESULTS

The key overarching theme to emerge from interviews with 38 parents was the importance of the terminology used to refer to the death of their baby. Parents who were told they were 'losing a baby' rather than 'having a miscarriage' were more prepared for the realities of labour, the birth experience and for making decisions around seeing and holding their baby. Appropriate terminology validated their loss, and impacted on parents' health and wellbeing immediately following bereavement and in the longer term.

CONCLUSION

For parents experiencing the death of their baby at the margins between miscarriage, stillbirth and neonatal death, ensuring the use of appropriate terminology that reflects parents' preferences is vital. This helps to validate their loss and prepare them for the experiences of labour and birth. Reflecting parents' language preferences combined with compassionate bereavement care is likely to have a positive impact on parents' experiences and improve longer-term outcomes.

TWEETABLE ABSTRACT

Describing baby loss shortly before 24 weeks of gestation as a 'miscarriage' does not prepare parents for labour and birth, seeing their baby and making memories.

"The communication and support from the health professional is incredibly important": A qualitative study exploring the processes and practices that support parental decision-making about postmortem examination

Background

Consent rates for postmortem (PM) examination in the perinatal and paediatric setting have dropped significantly in the United Kingdom, the United States, and the Western Europe. We explored the factors that act as facilitators or barriers to consent and identified processes and practices that support parental decision‐making.

Methods

A qualitative study conducted with bereaved parents, parent advocates, and health care professionals in the United Kingdom. Analysis was conducted on 439 free‐tect comments within a cross‐sectional survey, interviews with a subset of 20 survey respondents and 25 health professionals, and a focus group with five parent advocates.

Results

Three broad parental decision‐making groups were identified: 1, “Not open to postmortem examination”; 2, “Consent regardless of concerns”; and 3, “Initially undecided.” Decisional drivers that were particularly important for this “undecided” group were “the initial approach,” “adjustment and deliberation,” “detailed discussion about the procedure,” and “formal consent.” The way in which these were managed by health care staff significantly impacted whether those parents' consented to PM, particularly for those who are ambivalent about the procedure.

Conclusions

We propose a set of recommendations to improve the way PM counselling and consent is managed. Adopting such measures is likely to lead to improved family experience and more consistent and high‐quality discussion regarding PM.

What's already known about this topic?

There has been a significant decline in uptake of paediatric post mortem, despite evidence that it provides clinically useful data in between 22% and 76% of cases.

What does this study add?

This study identifies key actions by health care staff that are highly influential in whether or not parents' consent to the postmortem procedure. Recommendations for practice are also provided.

Availability of less invasive prenatal, perinatal and paediatric autopsy will improve uptake rates: a mixed-methods study with bereaved parents

Objective

To investigate whether less invasive methods of autopsy would be acceptable to bereaved parents and likely to increase uptake.

Design

Mixed methods study.

Setting

Bereaved parents recruited prospectively across seven hospitals in England and retrospectively through four parent support organisations.

Sample

Eight hundred and fifty‐nine surveys and 20 interviews with bereaved parents.

Methods

Cross‐sectional survey and qualitative semi‐structured telephone interviews.

Main outcome measures

Likely uptake, preferences, factors impacting decision‐making, views on different autopsy methods.

Results

Overall, 90.5% of participants indicated that they would consent to some form of less invasive autopsy [either minimally invasive autopsy (MIA), non‐invasive autopsy (NIA) or both]; 53.8% would consent to standard autopsy, 74.3% to MIA and 77.3% to NIA. Regarding parental preferences, 45.5% preferred MIA, 30.8% preferred NIA and 14.3% preferred standard autopsy. Participants who indicated they would decline standard autopsy but would consent to a less invasive option were significantly more likely to have a lower educational level (odds ratio 0.49; 95% CI 0.35–0.70; P = 0.000062). Qualitative findings suggest that parents value NIA because of the lack of any incision and MIA is considered a good compromise as it enables tissue sampling while easing the parental burden associated with consenting to standard autopsy.

Conclusion

Less invasive methods of autopsy are acceptable alternatives for bereaved parents, and if offered, are likely to increase uptake and improve parental experience. Further health economic, validation and implementation studies are now required to assess the viability of offering these in routine widespread clinical care.

Tweetable abstract

Mixed methods UK study finds less invasive methods of autopsy are acceptable alternatives for bereaved parents, and if offered, are likely to increase uptake and improve parental experience.

Mixed methods UK study finds less invasive methods of autopsy are acceptable alternatives for bereaved parents, and if offered, are likely to increase uptake and improve parental experience.

Role of Androgen Receptor Variants in Prostate Cancer: Report from the 2017 Mission Androgen Receptor Variants Meeting

CONTEXT

Although a number of studies have demonstrated the importance of constitutively active androgen receptor variants (AR-Vs) in prostate cancer, questions still remain about the precise role of AR-Vs in the progression of castration-resistant prostate cancer (CRPC).

OBJECTIVE

Key stakeholders and opinion leaders in prostate cancer convened on May 11, 2017 in Boston to establish the current state of the field of AR-Vs.

EVIDENCE ACQUISITION

The meeting "Mission Androgen Receptor Variants" was the second of its kind sponsored by the Prostate Cancer Foundation (PCF). This invitation-only event was attended by international leaders in the field and representatives from sponsoring organizations (PCF and industry sponsors). Eighteen faculty members gave short presentations, which were followed by in-depth discussions. Discussions focused on three thematic topics: (1) potential of AR-Vs as biomarkers of therapeutic resistance; (2) role of AR-Vs as functionally active CRPC progression drivers; and (3) utility of AR-Vs as therapeutic targets in CRPC.

EVIDENCE SYNTHESIS

The three meeting organizers synthesized this meeting report, which is intended to summarize major data discussed at the meeting and identify key questions as well as strategies for addressing these questions. There was a critical consensus that further study of the AR-Vs is an important research focus in CRPC. Contrasting views and emphasis, each supported by data, were presented at the meeting, discussed among the participants, and synthesized in this report.

CONCLUSIONS

This article highlights the state of knowledge and outlines the most pressing questions that need to be addressed to advance the AR-V field.

PATIENT SUMMARY

Although further investigation is needed to delineate the role of androgen receptor (AR) variants in metastatic castration-resistant prostate cancer, advances in measurement science have enabled development of blood-based tests for treatment selection. Detection of AR variants (eg, AR-V7) identified a patient population with poor outcomes to existing AR-targeting therapies, highlighting the need for novel therapeutic agents currently under development.

A signature of miRNAs in the blood to help prognosticate prostate cancer at the time of diagnosis

e16558

Background: Prostate cancer (PCa) is the most commonly diagnosed cancer in men. Around 80% of PCas are diagnosed as early, localised stage yet a subset of these will metastasise and eventually prove fatal. Management decisions are based on risk stratification systems. However, these systems are not able to clearly distinguish indolent from aggressive PCa’s and as a result many patients with indolent cancers may be over treated. Circulating microRNAs (miRNA) may be an easily accessible, suitable biomarker to distinguish true indolent from clinically significant early PCas thus reducing overtreatments. Methods: Blood samples from 24 men with benign prostatic hypertrophy (BPH, n = 8), localised PCa (n = 8) or metastatic PCa (n = 8) were collected at time of diagnosis. All men had intact prostates and were naïve to any endocrine or other cancer therapy. A platform of circulating miRNAs were analysed in serum using Abcam FireflyTM technology. Data collected were independently verified using real-time qPCR (Exiqon TM ). The miRNAs identified as being significantly different between groups were then analysed in a published dataset. Results: Serum levels of seven of the miRs examined were significantly different in patients with prostate cancer compared to control across both platforms (miR-10b, miR-125b, miR-210, miR-21, miR-378a, miR-483 and miR93 all with P values < 0.005). A further four miRNAs could differentiate between the benign and metastatic cohorts (miR-126 P = 0.008, miR-150 P = 0.05, miR375 P = 0.007). Kaplein-Meier analysis further identified that the serum levels of four miRNAs showed significant association with survival rates (miR-21 P = 0.032, miR-126 P = 0.032, miR-150 P = 0.032, miR-93 P = 0.019). On examination in a cohort of 280 men from The Cancer Genome Atlas (TCGA), four miRs from the cohort had significantly different expression in patients who eventually relapsed (miR-21 P = 0.048, miR-375 P = 0.021, miR-210 P = 0.0003, miR-93 P = 0.008) Conclusions: Our circulating miRNA based signature could be used to stratify men at prostate cancer diagnosis and help identify those who are likely to harbour micro metastases and would benefit more from an early radical treatment. The data is being validated in larger cohorts.

A circulating miRNA signature to help prognosticate at prostate cancer diagnosis

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Background: Prostate cancer (PCa) is the most commonly diagnosed cancer in men. Around 80% of PCas are diagnosed as early, localised stage yet a subset of these will metastasise and eventually prove fatal. Management decisions are based on risk stratification systems. However, these systems are not able to clearly distinguish indolent from aggressive PCa’s and as a result many patients with indolent cancers may be over treated. Circulating microRNAs (miRNA) may be an easily accessible, suitable biomarker to distinguish true indolent from clinically significant early prostate cancers (PCa) thus reducing overtreatments. Methods: Blood samples from 24 men with benign prostatic hypertrophy (BPH, n = 8), localised PCa (n = 8) or metastatic PCa (n = 8) were collected at time of diagnosis. All men had intact prostates and were naïve to any endocrine or other cancer therapy. A platform of circulating miRNAs were analysed in serum using Abcam Firefly technology. Data collected were independently verified using real-time qPCR (Exiqon). The miRNAs identified as being significantly different between groups were then analysed in a published dataset. Results: Serum levels of seven of the miRs examined were significantly different in patients with prostate cancer compared to control across both platforms (miR-10b, miR-125b, miR-210, miR-21, miR-378a, miR-483 and miR93 all with P values < 0.005). A further four miRNAs could differentiate between the benign and metastatic cohorts (miR-126 P = 0.008, miR-150 P = 0.05, miR375 P = 0.007). Kaplein-Meier analysis further identified that the serum levels of four miRNAs showed significant association with survival rates (miR-21 P = 0.032, miR-126 P = 0.032, miR-150 P = 0.032, miR-93 P = 0.019). On examination in a cohort of 280 men from The Cancer Genome Atlas (TCGA), four miRs from the cohort had significantly different expression in patients who eventually relapsed (miR-21 P = 0.048, miR-375 P = 0.021, miR-210 P = 0.0003, miR-93 P = 0.008) Conclusions: Our circulating miRNA based signature could be used to stratify men at prostate cancer diagnosis and help identify those who are likely to harbour micro metastases and would benefit more from an early radical treatment. The data is being validated in larger cohorts.

Cell-lineage specificity and role of AP-1 in the prostate fibroblast androgen receptor cistrome

Androgen receptor (AR) signalling in fibroblasts is important in prostate development and carcinogenesis, and is inversely related to prostate cancer mortality. However, the molecular mechanisms of AR action in fibroblasts and other non-epithelial cell types are largely unknown. The genome-wide DNA binding profile of AR in human prostate fibroblasts was identified by chromatin immunoprecipitation sequencing (ChIP-Seq), and found to be common to other fibroblast lines but disparate from AR cistromes of prostate cancer cells and tissue. Although AR binding sites specific to fibroblasts were less well conserved evolutionarily than those shared with cancer epithelia, they were likewise correlated with androgen regulation of fibroblast gene expression. Whereas FOXA1 is the key pioneer factor of AR in cancer epithelia, our data indicated that AP-1 likely plays a more important role in the AR cistrome in fibroblasts. The specificity of AP-1 and FOXA1 to binding in these cells is demonstrated using immunoblot and immunohistochemistry. Importantly, we find the fibroblast cistrome is represented in whole tissue/in vivo ChIP-seq studies at both genomic and resulting protein levels, highlighting the importance of the stroma in whole tissue -omic studies. This is the first nuclear receptor ChIP-seq study in prostatic fibroblasts, and provides novel insight into the action of fibroblast AR in prostate cancer.

Experiences with maternal and perinatal death reviews in the UK--the MBRRACE-UK programme

Established in 1952, the programme of surveillance and Confidential Enquiries into Maternal Deaths in the UK is the longest running such programme worldwide. Although more recently instituted, surveillance and confidential enquiries into perinatal deaths are also now well established nationally. Recent changes to funding and commissioning of the Enquiries have enabled both a reinvigoration of the processes and improvements to the methodology with an increased frequency of future reporting. Close engagement with stakeholders and a regulator requirement for doctors to participate have both supported the impetus for involvement of all professionals leading to greater potential for improved quality of care for women and babies.

Phosphorylation of activating transcription factor-2 (ATF-2) within the activation domain is a key determinant of sensitivity to tamoxifen in breast cancer

Activating transcription factor-2 (ATF-2) has been implicated as a tumour suppressor in breast cancer (BC). c-JUN N-terminal kinase (JNK) and p38 MAPK phosphorylate ATF-2 within the activation domain (AD), which is required for its transcriptional activity. To date, the role of ATF-2 in determining response to endocrine therapy has not been explored. Effects of ATF-2 loss in the oestrogen receptor (ER)-positive luminal BC cell line MCF7 were explored, as well as its role in response to tamoxifen treatment. Genome-wide chromatin binding patterns of ATF-2 when phosphorylated within the AD in MCF-7 cells were determined using ChIP-seq. The expression of ATF-2 and phosphorylated ATF-2 (pATF-2-Thr71) was determined in a series of 1,650 BC patients and correlated with clinico-pathological features and clinical outcome. Loss of ATF-2 diminished the growth-inhibitory effects of tamoxifen, while tamoxifen treatment induced ATF-2 phosphorylation within the AD, to regulate the expression of a set of 227 genes for proximal phospho-ATF-2 binding, involved in cell development, assembly and survival. Low expression of both ATF-2 and pATF-2-Thr71 was significantly associated with aggressive pathological features. Furthermore, pATF-2 was associated with both p-p38 and pJNK1/2 (< 0.0001). While expression of ATF-2 is not associated with outcome, pATF-2 is associated with longer disease-free (p = 0.002) and BC-specific survival in patients exposed to tamoxifen (p = 0.01). Furthermore, multivariate analysis confirmed pATF-2-Thr71 as an independent prognostic factor. ATF-2 is important for modulating the effect of tamoxifen and phosphorylation of ATF-2 within the AD at Thr71 predicts for improved outcome for ER-positive BC receiving tamoxifen.

Prostate cancer cell malignancy via modulation of HIF-1α pathway with isoflurane and propofol alone and in combination

Background:

Surgery is considered to be the first line treatment for solid tumours. Recently, retrospective studies reported that general anaesthesia was associated with worse long-term cancer-free survival when compared with regional anaesthesia. This has important clinical implications; however, the mechanisms underlying those observations remain unclear. We aim to investigate the effect of anaesthetics isoflurane and propofol on prostate cancer malignancy.

Methods:

Prostate cancer (PC3) cell line was exposed to commonly used anaesthetic isoflurane and propofol. Malignant potential was assessed through evaluation of expression level of hypoxia-inducible factor-1α (HIF-1α) and its downstream effectors, cell proliferation and migration as well as development of chemoresistance.

Results:

We demonstrated that isoflurane, at a clinically relevant concentration induced upregulation of HIF-1α and its downstream effectors in PC3 cell line. Consequently, cancer cell characteristics associated with malignancy were enhanced, with an increase of proliferation and migration, as well as development of chemoresistance. Inhibition of HIF-1α neosynthesis through upper pathway blocking by a PI-3K-Akt inhibitor or HIF-1α siRNA abolished isoflurane-induced effects. In contrast, the intravenous anaesthetic propofol inhibited HIF-1α activation induced by hypoxia or CoCl₂. Propofol also prevented isoflurane-induced HIF-1α activation, and partially reduced cancer cell malignant activities.

Conclusions:

Our findings suggest that modulation of HIF-1α activity by anaesthetics may affect cancer recurrence following surgery. If our data were to be extrapolated to the clinical setting, isoflurane but not propofol should be avoided for use in cancer surgery. Further work involving in vivo models and clinical trials is urgently needed to determine the optimal anaesthetic regimen for cancer patients.

The full spectrum of handlebar injuries in children: a decade of experience

BACKGROUND

Traumatic paediatric handlebar injury (HBI) is known to occur with different vehicles, affect different body regions, and have substantial associated morbidity. However, previous handlebar injury research has focused on the specific combination of abdominal injury and bicycle riding. Our aim was to fully describe the epidemiology and resultant spectrum of injuries caused by a HBI.

METHODS

Retrospective data analysis of all paediatric patients (<18 years) in a prospectively identified trauma registry over a 10-year period. Primary outcome was the HBI, its location and management. The effects of patient age, vehicle type, the impact region, and Injury Severity Score (ISS) were also evaluated. HBI patients were compared against a cohort injured while riding similar vehicles, but not having sustained a HBI.

RESULTS

1990 patients were admitted with a handlebar-equipped vehicle trauma; 236 (11.9%) having sustained a HBI. HBI patients were twice as likely to be aged between 6 and 14 years old compared with non-HBI patients (OR 2.2; 95% CI 1.5-3.2). 88.6% of the HBI patients sustained an isolated injury, and 45.3% had non-abdominal handlebar impact. There were no significant differences in median ISS (p=0.4) or need for operative intervention (OR 1.1; 95% CI 0.9-1.5) between HBI and non-HBI patients. HBI patients had a significantly longer LOS (1.8 days vs. 1.2 days; p=0.001), and more frequently required a major operation (OR 3.4; 95% CI 2.2-5.4). The majority of splenic, renal and hepatic injuries were managed conservatively.

CONCLUSIONS

Although the majority of paediatric HBI is associated with both intra-abdominal injury and bicycle riding, it produces a spectrum of potentially serious injuries and patients are more likely to undergo major surgery. Therefore these patients should always be treated with a high degree of suspicion.

Chromatographic Hydrophobicity Index by Fast-Gradient RP-HPLC: A High-Throughput Alternative to log P/log D

A new chromatographic hydrophobicity index (CHI) is described which can be used as part of a protocol for high-throughput (50-100 compounds/day) physicochemical property profiling for rational drug design. The index is derived from retention times (t(R)) observed in a fast gradient reversed-phase HPLC method. The isocratic retention factors (log k') were measured for a series of 76 structurally unrelated compounds by using various concentrations of acetonitrile in the mobile phase. By plotting the log k' as a function of the acetonitrile concentration, the slope (S) and the intercept (log k'(w)) values were calculated. The previously validated index of hydrophobicity φ(0) was calculated as -log k'(w)/S. A good linear correlation was obtained between the gradient retention time values, t(R) and the isocratically determined φ(0) values for the 76 compounds. The constants of this linear correlation can be used to calculate CHI. For most compounds, CHI is between 0 and 100 and in this range it approximates to the percentage (by volume) of acetonitrile required to achieve an equal distribution of compound between the mobile and the stationary phases. CHI values can be measured using acidic, neutral, or slightly basic eluents. Values corresponding to the neutral form of molecules could be measured for 52 of the compounds and showed good correlation (r = 0.851) to the calculated octanol/water partition coefficient (c log P) values.

Allosteric conversation in the androgen receptor ligand-binding domain surfaces

Androgen receptor (AR) is a major therapeutic target that plays pivotal roles in prostate cancer (PCa) and androgen insensitivity syndromes. We previously proposed that compounds recruited to ligand-binding domain (LBD) surfaces could regulate AR activity in hormone-refractory PCa and discovered several surface modulators of AR function. Surprisingly, the most effective compounds bound preferentially to a surface of unknown function [binding function 3 (BF-3)] instead of the coactivator-binding site [activation function 2 (AF-2)]. Different BF-3 mutations have been identified in PCa or androgen insensitivity syndrome patients, and they can strongly affect AR activity. Further, comparison of AR x-ray structures with and without bound ligands at BF-3 and AF-2 showed structural coupling between both pockets. Here, we combine experimental evidence and molecular dynamic simulations to investigate whether BF-3 mutations affect AR LBD function and dynamics possibly via allosteric conversation between surface sites. Our data indicate that AF-2 conformation is indeed closely coupled to BF-3 and provide mechanistic proof of their structural interconnection. BF-3 mutations may function as allosteric elicitors, probably shifting the AR LBD conformational ensemble toward conformations that alter AF-2 propensity to reorganize into subpockets that accommodate N-terminal domain and coactivator peptides. The induced conformation may result in either increased or decreased AR activity. Activating BF-3 mutations also favor the formation of another pocket (BF-4) in the vicinity of AF-2 and BF-3, which we also previously identified as a hot spot for a small compound. We discuss the possibility that BF-3 may be a protein-docking site that binds to the N-terminal domain and corepressors. AR surface sites are attractive pharmacological targets to develop allosteric modulators that might be alternative lead compounds for drug design.

Impact of Analytical Bias in Metabonomic Studies of Human Blood Serum and Plasma

Concurrent with the explosion in the number of publications reporting biomarker discovery by profiling technologies, such as proteomics and pattern recognition, has been the increase in evidence highlighting the susceptibility of these approaches to analytical and experimental bias. The work presented here addresses these timely issues by delivering a detailed characterization of the effect of common sources of bias in clinical studies on serum and plasma profiles generated by a key technology in metabonomics, NMR spectroscopy. Specifically, differences in composition when blood samples were collected onto and in the absence of ice, over a series of serum-clot contact times, the stability of NMR-prepared samples over time and the effect on the metabolic profile of freeze-thawing were examined. While differences between individuals were far greater than variation from any other experimental factor, each of the conditions examined did cause slight alterations to the NMR profile that could produce a systematic bias. Variation due to clotting time caused changes in energy metabolites, which were delayed by ice with no other spectral effects. Room-temperature stability and hence NMR spectral repeatability were high (<1% intrasample variation). Higher molecular weight species such as lipoproteins were more susceptible to the variations present in the examined factors. These observations have implications for profiling study design, and hence, our results form a new and valuable resource for those attempting clinical metabolic profiling, for regulatory agencies involved in the licensing of clinical tests and in the generation of international reporting standards for metabonomics.

Exposure to repeat doses of antenatal glucocorticoids is associated with altered cardiovascular status after birth

OBJECTIVE

To determine if exposure to more than one course of antenatal glucocorticoids is associated with changes in infant blood pressure and myocardial wall thickness in the first month after birth.

DESIGN

Prospective cohort study.

SETTING

Tertiary neonatal intensive care unit.

PARTICIPANTS

Mothers who were eligible for but declined to enter a randomised trial of repeated doses of antenatal glucocorticoids (ACTORDS)-that is, who had a singleton, twin, or triplet pregnancy at <32 weeks gestation, had received an initial course of glucocorticoids seven or more days previously, and were considered to be at continued risk of preterm birth.

MAIN OUTCOME MEASURES

Blood pressure daily for the first week then weekly until 4 weeks of age. End diastolic interventricular septal and left ventricular posterior wall (EDIVS and EDLVPW) thickness at 48-72 hours after birth.

RESULTS

Thirty seven women were enrolled and delivered 50 infants. Thirty mothers (39 infants) were exposed to one course of glucocorticoids, and seven mothers (11 infants) to more than one course. Blood pressures were higher in the first week after birth in infants exposed to multiple courses of glucocorticoids, and in infants with a latency between last exposure and delivery of less than seven days. Systolic blood pressure on day 1 was >2SD above published normal ranges in 67% of babies exposed to multiple courses and 24% of babies exposed to a single course of glucocorticoids (p = 0.04). There was no difference between groups in thickness of the EDIVS or EDLVPW. However, 44/50 (88%) babies had EDIVS and 49/50 (98%) babies had EDLVPW thickness >2 SD above the expected mean for birth weight and gestation. EDIVS but not EDLVPW thickness increased with increasing latency (mean 0.02 mm/day, p = 0.03).

CONCLUSION

Future randomised trials should assess the long term effects of exposure to antenatal glucocorticoids, particularly multiple courses, on the cardiovascular status of the infant.

Unique selectivity of perfluorinated stationary phases with 2,2,2-trifluoroethanol as organic mobile phase modifier

The selectivity of Luna C18 Xterra C18 and Fluophase (perfluorinated C6) stationary phases has been investigated with aqueous acetonitrile, methanol and 2,2,2-trifluoroethanol mobile phases using linear solvation equations. The gradient retention times of a set of 60 compounds with known molecular descriptors have been determined. Linear solvation equations have been set up to describe the relationship between the gradient retention times and the molecular properties. The selectivity of the stationary phase/mobile phase systems was characterised by the regression coefficients of the molecular descriptors. The perfluorinated stationary phase showed very different selectivity using 2,2,2-trifluoroethanol (TFE) as co-solvent. Compounds with H-bond donor functionality were retained much less than in the other investigated high-performance liquid chromatography (HPLC) systems. This unique selectivity can be explained by the stronger adsorption of trifluoroethanol on the perfluorinated stationary phase surface, than on the hydrocarbon surface. It suggests the importance of the adsorbed organic modifiers in the separation mechanism during reversed-phase HPLC.

Effect of 4-vinylcyclohexene on micronucleus formation in the bone marrow of rats and mice

This study was conducted to evaluate the potential of 4-vinylcyclohexene (VCH) to induce micronuclei in the bone marrow of mice and rats. Male and female Crl:CD BR (Sprague-Dawley) rats and B6C3F1/CrBR mice were exposed to VCH 6 hr/day for 2 days or for 13 weeks. In the 2-day study, mice were exposed by inhalation to 0, 250, 500, or 1000 ppm, and rats were exposed to 0, 500, 1000, or 2000 ppm. In the 13-week study, mice were exposed to 0, 50, 250, or 1000 ppm, and rats were exposed to 0, 250, 1000, or 1500 ppm. In each study, a separate group of mice was exposed to 1000 ppm 1,3-butadiene (BD) so that a comparison could be made between the two compounds. Likewise, cyclophosphamide was also included for rats as a positive control. Bone marrow was collected from VCH-exposed animals approximately 24 h and 48 h after the final exposure. There were no statistically significant increases in micronucleatedpolychromatic erythrocytes (MN-PCEs) among VCH-treated mice and rats at any dose level or sampling interval at either 2-days or 13-weeks. Also, no statistically significant differences in the polychromatic erythrocytes (PCE) to normochromatic erythrocytes (NCE) ratios were observed in any of the VCH-treated mice and rats compared to air-exposed animals. As expected, both the butadiene-treated mice and the cyclophosphamide-treated rats showed significantly more MN-PCEs than the control animals.

Rapid method for the estimation of octanol/water partition coefficient (log P(oct)) from gradient RP-HPLC retention and a hydrogen bond acidity term (zetaalpha(2)(H))

We propose a rapid method for the measurement of octanol/water partition coefficients (log P(oct)) via fast gradient reversed phase retention and the calculation of the hydrogen bond acidity of the compounds. The cycle time of the generic gradient HPLC method is 5 minutes. The general solvation equation obtained for the log Poct values and the fast gradient Chromatographic Hydrophobicity Indices with acetonitrile (CHI(ACN)) and methanol

Chronic toxicity/oncogenicity study of styrene in CD-1 mice by inhalation exposure for 104 weeks

Groups of 70 male and 70 female Charles River CD-1 mice were exposed whole body to styrene vapor at 0, 20, 40, 80 or 160 ppm 6 h per day 5 days per week for 98 weeks (females) or 104 weeks (males). The mice were observed daily; body weights, food and water consumption were measured periodically, a battery of hematological and clinical pathology examinations were conducted at weeks 13, 26, 52, 78 and 98 (females)/104 (males). Ten mice of each gender per group were pre-selected for necropsy after 52 and 78 weeks of exposure and the survivors of the remaining 50 of each gender per group were necropsied after 98 or 104 weeks. An extensive set of organs from the control and high-exposure mice were examined histopathologically, whereas target organs, gross lesions and all masses were examined in all other groups. Styrene had no effect on survival in males. Two high-dose females died (acute liver toxicity) during the first 2 weeks; the remaining exposed females had a slightly higher survival than control mice. Levels of styrene and styrene oxide (SO) in the blood at the end of a 6 h exposure during week 74 were proportional to exposure concentration, except that at 20 ppm the SO level was below the limit of detection. There were no changes of toxicological significance in hematology, clinical chemistry, urinalysis or organ weights. Mice exposed to 80 or 160 ppm gained slightly less weight than the controls. Styrene-related non-neoplastic histopathological changes were found only in the nasal passages and lungs. In the nasal passages of males and females at all exposure concentrations, the changes included respiratory metaplasia of the olfactory epithelium with changes in the underlying Bowman's gland; the severity increased with styrene concentration and duration of exposure. Loss of olfactory nerve fibers was seen in mice exposed to 40, 80 or 160 ppm. In the lungs, there was decreased eosinophilia of Clara cells in the terminal bronchioles and bronchiolar epithelial hyperplasia extending into alveolar ducts. Increased tumor incidence occurred only in the lung. The incidence of bronchioloalveolar adenomas was significantly increased in males exposed to 40, 80 or 160 ppm and in females exposed to 20, 40 and 160 ppm. The increase was seen only after 24 months. In females exposed to 160 ppm, the incidence of bronchiolo-alveolar carcinomas after 24 months was significantly greater than in the controls. No difference in lung tumors between control and styrene-exposed mice was seen in the intensity or degree of immunostaining, the location of tumors relative to bronchioles or histological type (papillary, solid or mixed). It appears that styrene induces an increase in the number of lung tumors seen spontaneously in CD-1 mice.

Analysis of the steroid receptor coactivator 1 (SRC1)-CREB binding protein interaction interface and its importance for the function of SRC1

The transcriptional activity of nuclear receptors is mediated by coactivator proteins, including steroid receptor coactivator 1 (SRC1) and its homologues and the general coactivators CREB binding protein (CBP) and p300. SRC1 contains an activation domain (AD1) which functions via recruitment of CBP and and p300. In this study, we have used yeast two-hybrid and in vitro interaction-peptide inhibition experiments to map the AD1 domain of SRC1 to a 35-residue sequence potentially containing two alpha-helices. We also define a 72-amino-acid sequence in CBP necessary for SRC1 binding, designated the SRC1 interaction domain (SID). We show that in contrast to SRC1, direct binding of CBP to the estrogen receptor is weak, suggesting that SRC1 functions primarily as an adaptor to recruit CBP and p300. In support of this, we show that the ability of SRC1 to enhance ligand-dependent nuclear receptor activity in transiently transfected cells is dependent upon the integrity of the AD1 region. In contrast, the putative histone acetyltransferase domain, the Per-Arnt-Sim basic helix-loop-helix domain, the glutamine-rich domain, and AD2 can each be removed without loss of ligand-induced activity. Remarkably, a construct corresponding to residues 631 to 970, which contains only the LXXLL motifs and the AD1 region of SRC1, retained strong coactivator activity in our assays.

Characterizing the selectivity of stationary phases and organic modifiers in reversed-phase high-performance liquid chromatographic systems by a general solvation equation using gradient elution

Retention data for a set of 69 compounds using rapid gradient elution are obtained on a wide range of reversed-phase stationary phases and organic modifiers. The chromatographic stationary phases studied are Inertsil (IN)-ODS, pentafluorophenyl, fluoro-octyl, n-propylcyano, Polymer (PLRP-S 100), and hexylphenyl. The organic solvent modifiers are 2,2,2-trifluoroethanol (TFE); 1,1,1,3,3,3-hexafluoropropan-2-ol (HFIP); isopropanol; methanol (MeOH); acetonitrile (AcN); tetrahydrofuran; 1,4-dioxane; N,N-dimethylformamide; and mixed solvents of dimethylsulfoxide (DMSO) with AcN and DMSO with MeOH (1:1). A total of 25 chromatographic systems are analyzed using a solvation equation. In general, most of the systems give reasonable statistics. The selectivity of the reversed phase-high-performance liquid chromatographic (HPLC) systems with respect to the solute's dipolarity-polarity, hydrogen-bond acidity, and basicity are reflected in correspondingly large coefficients in the solvation equation. We wanted to find the most orthogonal HPLC systems, showing the highest possible selectivity difference in order to derive molecular descriptors using the gradient retention times of a compound. We selected eight chromatographic systems that have a large range of coefficients of interest (s, a, and b) similar to those found in water-solvent partitions used previously to derive molecular descriptors. The systems selected are IN-ODS phases with AcN, MeOH, TFE, and HFIP as mobile phase, PLRP-S 100 phase with AcN, propylcyano phase with AcN and MeOH, and fluorooctyl phase with TFE. Using the retention data obtained for a compound in the selected chromatographic systems, we can estimate the molecular descriptors with the faster and simpler gradient elution method.

Intravenous clonidine infusion in critically ill children: dose-dependent sedative effects and cardiovascular stability

Clonidine is used for analgesia and sedation in paediatric anaesthesia, but there are no data on its sedative properties and side effects in critically ill children. We studied 30 ventilated children aged 10 yr and under to determine an effective i.v. dosing range and to assess its cardiovascular effects. Twenty non-paralysed, ventilated children were given a background infusion of midazolam 50 micrograms kg-1 h-1 combined with a variable clonidine infusion (0.1-2 micrograms kg-1 h-1) to maintain optimal sedation. The effects of clonidine 1 microgram kg-1 h-1 on cardiac index were measured in 10 postoperative cardiac patients using a reverse Fick method. Dose-dependent sedation was achievable (713 out of 861 h) without cardiovascular side effects, but an infusion limit of clonidine 1 microgram kg-1 h-1 was inadequate in two patients. An increased dose limit of 2 micrograms kg-1 h-1 combined with midazolam 50 micrograms kg-1 h-1 achieved satisfactory sedation scores for 602 out of a total of 672 h studied with no failures. Clonidine in combination with midazolam at 1 microgram kg-1 h-1 was not associated with significant changes in heart rate arterial pressure or cardiac index.

Reproduction/developmental toxicity screening test in rats with orally-administered 1-hexene

This study was conducted to provide screening information concerning the potential systemic, reproductive and developmental toxicity of 1-hexene when administered orally, by gavage, to male and female rats using a modified OECD 421 protocol. 1-Hexene was administered at doses of 100, 500, and 1000 mg/kg/day in corn oil; the control group received the vehicle at an equivalent volume. The males were treated for 28 days prior to mating and until euthanasia (44 days of dosing). The females were treated for 14 days prior to mating and during mating, gestation, and lactation until euthanasia (41-55 total days of dosing). Females were allowed to deliver and rear their offspring until lactation day 4. The parental rats were subject to a gross and microscopic examination. Viability and development of the pups were followed through lactation day 4. There was no mortality, and there were no clinical signs of toxicity or differences in body weights, weight gain, feed consumption or organ weights. Copulation and fertility indices, precoital intervals, gestation lengths and pregnancy rates were comparable among the groups, and no signs of prolonged delivery or unusual nesting behaviors were noted. Pup viability, body weights, external observations and necropsy data were comparable among the groups. Pitted kidneys were observed at necropsy for two parental males in the 500 mg/kg/day group and three males in the 1000 mg/kg/day group. Microscopic changes in the kidneys of some male rats from the 100, 500, and 1000 mg/kg/day groups consisted of dose-related accumulations of hyaline droplets in the epithelial cells of the proximal convoluted tubules of the kidneys. In summary, the only treatment-related effect noted in this study was hydrocarbon nephropathy in male rats, which is not considered relevant for human health. The NOAEL for systemic and reproductive toxicity was 1000 mg/kg/day, excluding the finding of male rat hydrocarbon nephropathy.

Mother, daughter, patient, nurse: women's emotion work in aged care

This paper examines emotion work within the predominantly female environment of aged-care nursing, identifying phenomena which must be accounted for in a theory of emotional labour. These phenomena include the blurring of public and private in women's experiences and maternal models of care. Initial findings demonstrate the high levels of stress experienced by staff, related to emotional labour and to conflicts around the erosion of care standards. Sixteen women, from rural Australia, participated in the first stage of the research. The oldest was in her sixties, the youngest in her thirties. Length of aged-care experience ranged from 2 to 33 years. Although most of the women expected to still be in aged care in 5 years' time, they were negative in their attitudes to personal ageing, suggesting an ambivalence in their feelings about working in aged care. Three women nurses are the particular focus of this paper. Their narratives illustrate the intersection of private and public caring in nurses' lives and the implications of this for emotional labour. Phenomena such as dual caring, conflicts in insider-outsider roles, and transference are revealed in their narratives. We argue that the welfare of the recipient of gerontic nursing is linked to the well-being of the nurse-carer but that a cultural change is needed so as to recognize and value emotion work. However, endorsing Staden, we agree that such a change is dependent on the politicization of 'caring'. There is also need for further and broader research concerning the nature of emotional labour and the ethics of care.

Motor activity effects in female Fischer 344 rats exposed to isopropanol for 90 days

In a previous subchronic neurotoxicity study, increases in motor activity were observed for female rats after 9 and 13 weeks of exposure to 5000 ppm of isopropanol vapor. The present study was conducted to evaluate the reproducibility of these effects and, if reproducible, to assess the potential for reversibility following cessation of exposure. Two groups, each containing 30 female Fischer 344 rats, were exposed to concentrations of zero (control) and 5000 ppm of isopropanol vapor for 6 h per day, 5 days per week. Fifteen of the animals in the control and 5000 ppm groups were exposed for 9 weeks (designated as the 9-week subgroup), while the other 15 animals in each group were exposed for 13 weeks (designated as the 13-week subgroup). Motor activity was assessed for both subgroups prior to exposure and following 4, 7 and 9 weeks of exposure. Motor activity was also measured for rats in the 13-week subgroup following 11 and 13 weeks of exposure. These motor activity measurements were made 18-20 h following the end of the last exposure for that week. In addition, to evaluate the reversibility of motor activity effects, measurements were made on three occasions during the week following the final exposure for rats in both the 9-week and 13-week subgroups and weekly thereafter for five additional weeks for rats in the 13-week subgroup. Increases in cumulative test session motor activity counts were observed following 4, 7 and 9 weeks of exposure for rats in the 9-week subgroup. Increases in cumulative test session motor activity counts were also observed following 4, 7, 9, 11 and 13 weeks of exposure for rats in the 13-week subgroup. Reversibility of this effect was observed for rats in the 9-week subgroup within 2 days following the last exposure. Reversibility was also noted for rats in the 13-week subgroup but not until Study Week 15 (2 weeks following the last exposure). Minor changes were observed in the shape of the motor activity habituation curves for isopropanol-exposed animals in the 9-week and 13-week subgroups at ca. 50% of the measurement intervals beginning at Study Week 4. While most of these statistical changes were observed in conjunction with increases in cumulative test session motor activity, some were observed following time points where recovery of the cumulative test session motor activity counts had occurred. No change in the shape of the motor activity habituation curve was observed at 42 days following the last exposure, indicating that complete recovery of motor activity effects had occurred. Thus, repeated exposure of female rats to 5000 ppm of isopropanol produced reversible increases in motor activity.

Dermal absorption and pharmacokinetics of isopropanol in the male and female F-344 rat

Isopropanol (IPA), as a 70% aqueous solution, was applied under occluded conditions to the shaved backs of male and female Fischer F-344 rats for a period of 4 hr. Maximum analyzed blood concentrations of IPA were attained at 4 hr and decreased steadily following removal of the test material. Blood concentrations were below the limit of quantification at 8 hr. Acetone (ACE) blood levels rose steadily during the 4-hr exposures and continued to rise following removal of the test material, reaching peak analyzed levels at 4.5 hr (male) and 5 hr (females). ACE blood concentrations were below the limit of quantification at 24 hr. Basic pharmacokinetic parameters were similar for male and female rats with mean, first-order elimination half-lives for IPA and ACE of 0.8 to 0.9 hr and 2.1 to 2.2 hr, respectively. Following iv administration of [14C]IPA, 50-55% of the dose was eliminated as 14CO2 with lesser amounts recovered as expired volatiles or in urine. Total recoveries following iv administration were 83% for both males and females. Following a 4-hr dermal exposure to [14C]IPA (70% aqueous solution), 84-86% of the dose was recovered from the application site. Dermal absorption rates were calculated by two independent methods. The values obtained were 0.78 +/- 0.03 and 0.85 +/- 0.04 mg/cm2/hr for males and 0.77 +/- 0.13 and 0.78 +/- 0.16 mg/cm2/hr for females. Calculated permeability coefficients of 1.37 to 1.50 x 10(-3) cm/hr for males and 1.35 to 1.37 x 10(-3) cm/hr for females indicate that in the rat, IPA is rapidly absorbed dermally when applied under occluded conditions.