Effectiveness of remotely delivered motivational conversations on health outcomes in patients living with musculoskeletal conditions: A systematic review and meta-analysis

OBJECTIVE

To evaluate the efficacy of remotely delivered motivational conversations on health outcomes in musculoskeletal populations.

METHODS

Four electronic databases (inception-March 2022) were searched and combined with grey literature. Randomised control trials (RCTs) evaluating the effect of remotely delivered motivational conversation-based interventions within musculoskeletal populations, using valid measures of pain, disability, quality of life (QoL), or self-efficacy were included. Overall quality was assessed using GRADE criteria. Meta-analyses were performed using random effects models with pooled effect sizes expressed as standardised mean differences ( ± 95%CIs).

RESULTS

Twelve RCTs were included. Meta-analyses revealed very-low to moderate quality evidence that remote interventions have a positive effect on pain and disability both immediately post intervention and at long-term follow-up compared to control, and have a positive effect on self-efficacy immediately post intervention. There was no effect on QoL immediately post intervention or at long-term follow up.

CONCLUSION

Remotely delivered motivation-based conversational interventions have a positive effect on pain, disability, and self-efficacy but not on QoL.

PRACTICE IMPLICATIONS

Motivational conversations, delivered remotely, may be effective in improving some health-related outcomes in MSK populations. However, higher quality evidence is needed to determine optimal intervention durations, and dosing frequencies using sufficient sample sizes and follow-up time frames.

Physiotherapists' perspectives of barriers and facilitators to effective community provision after hip fracture: a qualitative study in England

PURPOSE

to investigate physiotherapists' perspectives of effective community provision following hip fracture.

METHODS

qualitative semi-structured interviews were conducted with 17 community physiotherapists across England. Thematic analysis drawing on the Theoretical Domains Framework identified barriers and facilitators to implementation of effective provision. Interviews were complemented by process mapping community provision in one London borough, to identify points of care where suggested interventions are in place and/or could be implemented.

RESULTS

four themes were identified: ineffective coordination of care systems, ineffective patient stratification, insufficient staff recruitment and retention approaches and inhibitory fear avoidance behaviours. To enhance care coordination, participants suggested improving access to social services and occupational therapists, maximising multidisciplinary communication through online notation, extended physiotherapy roles, orthopaedic-specific roles and seven-day working. Participants advised the importance of stratifying patients on receipt of referrals, at assessment and into appropriately matched interventions. To mitigate insufficient staff recruitment and retention, participants proposed return-to-practice streams, apprenticeship schemes, university engagement, combined acute-community rotations and improving job description advertisements. To reduce effects of fear avoidance behaviour on rehabilitation, participants proposed the use of patient-specific goals, patient and carer education, staff education in psychological strategies or community psychologist access. Process mapping of one London borough identified points of care where suggested interventions to overcome barriers were in place and/or could be implemented.

CONCLUSION

physiotherapists propose that effective provision of community physiotherapy following hip fracture could be improved by refining care coordination, utilising stratification techniques, employing enhanced recruitment and retainment strategies and addressing fear avoidance behaviours.

Embedding the rehabilitation treatment specification system (RTSS) into clinical practice: an evaluation of a pilot teaching programme

BACKGROUND

Deficiency in the provision and quality of treatment specification by rehabilitation clinicians impairs the ability to differentiate effective from ineffective elements of treatment. The standardised language of the rehabilitation treatment specification system (RTSS) has been proposed as a countermeasure. To date, there is no evidence of its use in clinical practice and what effect it may have. This study aimed to assess the ability of a pilot teaching programme to embed the RTSS into the clinical practice of an inpatient oncology physiotherapy team. The objectives were to evaluate the teaching programme's effect on; participants' familiarity and perceived benefit of the RTSS, its uptake, participants' clinical reasoning, and their feelings and attitudes towards adopting the RTSS. This study provides an evaluation of the pilot teaching programme which will subsequently inform a larger iteration in an ongoing Health Education England (HEE) project aiming to disseminate and embed the RTSS into physiotherapy practice to improve physiotherapists' treatment specification.

METHODS

A 6-week, multi-modal RTSS pilot teaching programme based upon socio-constructivist theory was delivered to 10 inpatient oncology physiotherapists at a large urban UK trust in 2021. Self-reported measures and clinical case note audits were assessed before and after the RTSS teaching programme to evaluate its effect on RTSS familiarity and perceived benefit, uptake, and clinical reasoning. A post-teaching focus group was undertaken. It was qualitatively analysed using an inductive, independent thematic approach to evaluate clinicians' reflection and adoption.

RESULTS

Ten participants (8F, 29.4(±3.5) years) with variable clinical experience completed the RTSS teaching programme (six 1-hour lecture/case-based-learning sessions weekly) with 85% mean attendance. Nine yielded complete data for analyses, and 7 participated in the focus group. There was significant improvements in self-reported familiarity and confidence using the RTSS. Furthermore, there was a significant effect of the teaching on self-reported clinical reasoning overall and specifically in knowledge and theory application. But this was not reflected in clinicians' uptake of RTSS language, nor in the quality of clinical reasoning emergent in their case notes. Qualitative analyses revealed that while clinicians' conceptual understanding and the relative advantage of using the RTSS in practice was pervasive, they articulated that translating its perceived academic disposition into their clinical practice a challenge.

CONCLUSIONS

The RTSS teaching programme was shown to be effective in improving self-reported measures of clinical reasoning, despite clinical uptake of the RTSS remaining low. Future iterations should be tested across physiotherapy specialisms and in a larger sample with consideration of pedagogical and cultural measures to support the clinical diffusion of the RTSS.

A Preoperative Spinal Education intervention for spinal fusion surgery designed using the Rehabilitation Treatment Specification System is safe and could reduce hospital length of stay, normalize expectations, and reduce anxiety

Aims

Psychoeducative prehabilitation to optimize surgical outcomes is relatively novel in spinal fusion surgery and, like most rehabilitation treatments, they are rarely well specified. Spinal fusion patients experience anxieties perioperatively about pain and immobility, which might prolong hospital length of stay (LOS). The aim of this prospective cohort study was to determine if a Preoperative Spinal Education (POSE) programme, specified using the Rehabilitation Treatment Specification System (RTSS) and designed to normalize expectations and reduce anxieties, was safe and reduced LOS.

Methods

POSE was offered to 150 prospective patients over ten months (December 2018 to November 2019) Some chose to attend (Attend-POSE) and some did not attend (DNA-POSE). A third independent retrospective group of 150 patients (mean age 57.9 years (SD 14.8), 50.6% female) received surgery prior to POSE (pre-POSE). POSE consisted of an in-person 60-minute education with accompanying literature, specified using the RTSS as psychoeducative treatment components designed to optimize cognitive/affective representations of thoughts/feelings, and normalize anxieties about surgery and its aftermath. Across-group age, sex, median LOS, perioperative complications, and readmission rates were assessed using appropriate statistical tests.

Results

In all, 65 (43%) patients (mean age 57.4 years (SD 18.2), 58.8% female) comprised the Attend-POSE, and 85 (57%) DNA-POSE (mean age 54.9 years (SD 15.8), 65.8% female). There were no significant between-group differences in age, sex, surgery type, complications, or readmission rates. Median LOS was statistically different across Pre-POSE (5 days ((interquartile range (IQR) 3 to 7)), Attend-POSE (3 (2 to 5)), and DNA-POSE (4 (3 to 7)), (p = 0.014). Pairwise comparisons showed statistically significant differences between Pre-POSE and Attend-POSE LOS (p = 0.011), but not between any other group comparison. In the Attend-POSE group, there was significant change toward greater surgical preparation, procedural familiarity, and less anxiety.

Conclusion

POSE was associated with a significant reduction in LOS for patients undergoing spinal fusion surgery. Patients reported being better prepared for, more familiar, and less anxious about their surgery. POSE did not affect complication or readmission rates, meaning its inclusion was safe. However, uptake (43%) was disappointing and future work should explore potential barriers and challenges to attending POSE. Cite this article: Bone Jt Open 2022;3(2):135–144.

Discharge after hip fracture surgery in relation to mobilisation timing by patient characteristics: linked secondary analysis of the UK National Hip Fracture Database

Background

Early mobilisation leads to a two-fold increase in the adjusted odds of discharge by 30-days compared to late mobilisation. Whether this association varies by patient characteristics identified as reasons for delayed mobilisation is unknown.

Methods

Audit data was linked to hospitalisation records for 133,319 patients 60 years or older surgically treated for hip fracture in England or Wales between 2014 and 2016. Adjusted proportional odds regression models tested whether the cumulative incidences of discharge differed between those mobilised early and those mobilised late for subgroups defined by dementia, delirium, hypotension, prefracture ambulation, and prefracture residence, accounting for the competing risk of death.

Results

Overall, 34,253 patients presented with dementia, 9818 with delirium, and 10,123 with hypotension. Prefracture, 100,983 were ambulant outdoors, 30,834 were ambulant indoors only, 107,144 were admitted from home, and 23,588 from residential care. 1502 had incomplete data for ambulation and 2587 for prefracture residence. 10, 8, 8, 12, and 12% fewer patients with dementia, delirium, hypotension, ambulant indoors only prefracture, or admitted from residential care mobilised early when compared to those who presented without dementia, delirium, hypotension, with outdoor ambulation prefracture, or admitted from home. The adjusted odds ratios of discharge by 30-days postoperatively among those who mobilised early compared with those who mobilised late were 1.71 (95% CI 1.62–1.81) for those with dementia, 2.06 (95% CI 1.98–2.15) without dementia, 1.56 (95% CI 1.41–1.73) with delirium, 2.00 (95% CI 1.93–2.07) without delirium, 1.83 (95% CI, 1.66–2.02) with hypotension, 1.95 (95% CI, 1.89–2.02) without hypotension, 2.00 (95% CI 1.92–2.08) with outdoor ambulation prefracture, 1.80 (95% CI 1.70–1.91) with indoor ambulation only prefracture, 2.30 (95% CI 2.19–2.41) admitted from home, and 1.64 (95% CI 1.51–1.77) admitted from residential care, accounting for the competing risk of death.

Conclusion

Irrespective of dementia, delirium, hypotension, prefracture ambulation or residence, early compared to late mobilisation increased the likelihood of hospital discharge by 30-days postoperatively. However, fewer patients with dementia, delirium, or hypotension, poorer prefracture ambulation, or from residential care mobilised early. There is a need reduce this care gap by ensuring sufficient resource to enable all patients to benefit from early mobilisation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-021-02624-w.

The 30-day survival and recovery after hip fracture by timing of mobilization and dementia : a UK database study

AIMS

The aim of this study to compare 30-day survival and recovery of mobility between patients mobilized early (on the day of, or day after surgery for a hip fracture) and patients mobilized late (two days or more after surgery), and to determine whether the presence of dementia influences the association between the timing of mobilization, 30-day survival, and recovery.

METHODS

Analysis of the National Hip Fracture Database and hospital records for 126,897 patients aged ≥ 60 years who underwent surgery for a hip fracture in England and Wales between 2014 and 2016. Using logistic regression, we adjusted for covariates with a propensity score to estimate the association between the timing of mobilization, survival, and recovery of walking ability.

RESULTS

A total of 99,667 patients (79%) mobilized early. Among those mobilized early compared to those mobilized late, the weighted odds ratio of survival was 1.92 (95% confidence interval (CI) 1.80 to 2.05), of recovering outdoor ambulation was 1.25 (95% CI 1.03 to 1.51), and of recovering indoor ambulation was 1.53 (95% CI 1.32 to 1.78) by 30 days. The weighted probabilities of survival at 30 days post-admission were 95.9% (95% CI 95.7% to 96.0%) for those who mobilized early and 92.4% (95% CI 92.0% to 92.8%) for those who mobilized late. The weighted probabilities of regaining the ability to walk outdoors were 9.7% (95% CI 9.2% to 10.2%) and indoors 81.2% (95% CI 80.0% to 82.4%), for those who mobilized early, and 7.9% (95% CI 6.6% to 9.2%) and 73.8% (95% CI 71.3% to 76.2%), respectively, for those who mobilized late. Patients with dementia were less likely to mobilize early despite observed associations with survival and ambulation recovery for those with and without dementia.

CONCLUSION

Early mobilization is associated with survival and recovery for patients (with and without dementia) after hip fracture. Early mobilization should be incorporated as a measured indicator of quality. Reasons for failure to mobilize early should also be recorded to inform quality improvement initiatives. Cite this article: Bone Joint J 2021;103-B(7):1317-1324.

500 30-DAY SURVIVAL AND RECOVERY AFTER HIP FRACTURE BY MOBILISATION TIMING AND DEMENTIA: A UK DATABASE STUDY

Introduction

To compare 30-day survival and recovery of prefracture ambulation between patients mobilised early (on the day of or day after surgery) and patients mobilised late (2 days of more after surgery) in England and Wales. To determine whether the presence of dementia influences the association between mobilisation timing and 30-day survival and recovery.

Methods

Secondary analysis of the UK National Hip Fracture Database linked to hospitalisation records for 126,897 patients 60 years or older who underwent surgery for nonpathological first hip fracture in England or Wales between 2014 and 2016. We used logistic regression to regress survival and ambulation recovery at 30-days with respect to mobilisation timing, overall and by dementia, with adjustment for confounding using a propensity score for mobilisation treatment with respect to confounders.

Results

Overall, 99,667 (79%) patients mobilised early. Among those who mobilised early compared to those who mobilised late, the weighted odds ratio of survival was 1.92 (95% CI 1.80–2.05), of recovering outdoor ambulation was 1.25 (95% CI 1.03–1.51), and of recovering indoor ambulation was 1.53 (95% CI 1.32–1.78) by 30 days. Early compared with late mobilisation led to a 3.8% increase in the weighted probability of survival, 22.8% increase in weighted probability of recovering outdoor ambulation and 10.0% increase in the weighted probability of recovering indoor ambulation, by 30-days. Patients with dementia were less likely to mobilise early but increases in survival and ambulation recovery were observed both for those with and without dementia.

Conclusion

Early mobilisation led to increase probability of survival and recovery for patients (with and without dementia) after hip fracture. Early mobilisation should be incorporated as a measured indicator of quality internationally. Reasons for failure to mobilise early should also be captured to inform quality improvement initiatives.

501 DISCHARGE AFTER HIP FRACTURE SURGERY IN RELATION TO MOBILISATION TIMING BY PATIENT CHARACTERISTICS: A NATIONAL DATABASE STUDY

Introduction

Early mobilisation leads to a two-fold increase in the odds of discharge by 30-days compared to late mobilisation. Whether this association varies by identified reasons for delayed mobilisation is unknown.

Methods

Audit data linked to hospitalisation records for patients 60 years or older surgically treated for hip fracture in England/Wales 2014–2016. Adjusted proportional odds regression models tested whether the cumulative incidences of discharge differed for early compared with late mobilisation across subgroups defined by dementia, delirium, hypotension, prefracture ambulation and residence, accounting for competing risk of death.

Results

Overall, 34,253 patients presented with dementia, 9,818 with delirium, and 10,123 with hypotension. Prefracture, 100,983 were ambulant outdoors, 30,834 were ambulant indoors only, 107,144 were admitted from home, and 23,588 from residential care. 10%, 8%, 8%, 12%, and 12% fewer patients with dementia, delirium, hypotension, ambulant indoors only prefracture, or from residential care mobilised early compared to those without dementia, delirium, hypotension, with outdoor ambulation prefracture, or from home. Adjusted odds ratios of discharge by 30-days for early compared with late mobilisation were 1.71 (95% CI 1.62–1.81) for those with dementia, 2.06 (95% CI 1.98–2.15) without dementia, 1.56 (95% CI 1.41–1.73) with delirium, 2.00 (95% CI 1.93–2.07) without delirium, 1.83 (95% CI, 1.66–2.02) with hypotension, 1.95 (95% CI, 1.89–2.02) without hypotension, 2.00 (95% CI 1.92–2.08) with outdoor ambulation prefracture, 1.80 (95% CI 1.70–1.91) with indoor ambulation only prefracture, 2.30 (95% CI 2.19–2.41) from home, and 1.64 (95% CI 1.51–1.77) from residential care.

Conclusion

Irrespective of dementia, delirium, hypotension, prefracture ambulation or residence, early compared to late mobilisation increased the likelihood of discharge by 30-days. Fewer patients with these conditions, poorer prefracture ambulation, or from residential care mobilised early. There is a need reduce this care gap by ensuring sufficient resource to enable all patients to benefit from early mobilisation.

34 Discharge After Hip Fracture Surgery by Mobilisation Timing: Secondary Analysis of the UK National Hip Fracture Database

Background

To maximise the benefits of hip fracture surgery the National Institute for Health and Care Excellence Clinical Guideline recommends mobilisation on the day after hip fracture surgery based a low to moderate quality trial with a small sample size. There is a need to generate additional evidence to support early mobilisation as a new UK Best Practice Tariff (BPT).

Objective

To determine whether mobilisation timing was associated with the cumulative incidence of hospital discharge by 30-days after hip fracture surgery, accounting for potential confounders and the competing risk of in-hospital death.

Method

We examined data for 135,105 patients 60 years or older who underwent surgery for nonpathological first hip fracture between January 2014 and December 2016 in any hospital in England or Wales. We tested whether the cumulative incidences of discharge differed between those mobilised early (within 36 hours of surgery) and those mobilised late accounting for potential confounders and the competing risk of in-hospital death.

Results

106,722 (79%) of patients first mobilised early. The average rate of discharge was 60.1 (95% CI 59.8–60.5) per 1,000 patient days, varying from 65.2 (95% CI 64.8–65.6) among those who mobilised early to 44.5 (95% CI 43.9–45.1) among those who mobilised late, accounting for the competing risk of death. By 30-days postoperatively, the crude and adjusted odds ratios of discharge were 2.26 (95% CI 2.2–2.32) and 1.93 (95% CI 1.86–1.99) respectively among those who first mobilised early compared to those who mobilised late, accounting for the competing risk of death.

Conclusion

Early mobilisation led to a near two fold increase in the adjusted odds of discharge by 30-days postoperatively. We recommend inclusion of mobilisation within 36 hours of surgery as a new UK BPT to help reduce delays to mobilisation currently experienced by one-fifth of patients surgically treated for hip fracture.

132 Physical Function Comparison of Acutely Unwell COVID-Negative Older Adults Pre-Pandemic and Through-Pandemic; “Covid-Protected”

Introduction

The risk of severe morbidity after COVID-19 infection is high in older adults (Lithander et al, 2020). Subsequent responsive UK Government guidance for older adults included self-isolation during the pandemic. It is therefore hypothesised that during the pandemic older adults are inadvertently deconditioned due to iatrogenic factors such as inactivity, social isolation, hospital-avoidance and malnutrition, and present with reduced resilience to illness and lower levels of function. The OPU continued to admit COVID-negative, or recently termed “COVID-protected”, patients throughout the pandemic. Data captured prior to, and during the COVID-19 pandemic has been compared to explore the implications on older adults, and elicit whether they are protected from the consequences of the pandemic?

Method

Demographic and physical function data (average 6 m gait-speed, Elderly Mobility Scale) were captured pre- and through-pandemic for all patients admitted to a COVID-negative OPU ward over a one month period. Ethical review was provided through local Trust governance process.

Results

Pre-pandemic 2019 (n = 67, mean(±SD) age 82.7(±8.2) years, 61%, hospital length-of-stay (LOS) 7.9(±7.3) days, hospital mortality-rate 7.2%) and through-pandemic 2020 (n = 73, 83.1(±8.3) years, 59%♀, LOS 9.0(±9.1) days, hospital mortality-rate 7.5%) data were captured during July 2019 and May 2020 respectively. There were no between-group differences in age [t(−.313) = 138, p = 0.755], gender [X², 1 df, p = 0.782], LOS [t(0.78) = 134, p = 0.44], or hospital mortality-rate [X² 1 df, p = 0.96]. Through-pandemic patients had a significantly slower 6 m gait-speed (0.11(±0.05) m.s-1) than pre-pandemic (0.16(±0.24) m.s-1); [t(2.74) = 93, p = 0.007] and lower median (IQR) Elderly Mobility Scale (4(6 IQR) vs 9 (12 IQR) [u = 866, p = 0.015]).

Conclusion

Our data indicates this relatively short period of self-isolation might have significant implications on the physical function of older adults. The likely mechanism is iatrogenic deconditioning. Critical Public Health and policy responses are required to mitigate these unforeseen risks by deploying prehabilitative counter-measures and accurately targeted hospital and community rehabilitation.

Discharge after hip fracture surgery by mobilisation timing: secondary analysis of the UK National Hip Fracture Database

Objective

To determine whether mobilisation timing was associated with the cumulative incidence of hospital discharge by 30 days after hip fracture surgery, accounting for potential confounders and the competing risk of in-hospital death.

Method

We examined data for 135,105 patients 60 years or older who underwent surgery for nonpathological first hip fracture between 1 January 2014 and 31 December 2016 in any hospital in England or Wales. We tested whether the cumulative incidences of discharge differed between those mobilised early (within 36 h of surgery) and those mobilised late, accounting for potential confounders and the competing risk of in-hospital death.

Results

A total of 106,722 (79%) of patients first mobilised early. The average rate of discharge was 39.2 (95% CI 38.9–39.5) per 1,000 patient days, varying from 43.1 (95% CI 42.8–43.5) among those who mobilised early to 27.0 (95% CI 26.6–27.5) among those who mobilised late, accounting for the competing risk of death. By 30-day postoperatively, the crude and adjusted odds ratios of discharge were 2.36 (95% CI 2.29–2.43) and 2.08 (95% CI 2.00–2.16), respectively, among those who first mobilised early compared with those who mobilised late, accounting for the competing risk of death.

Conclusion

Early mobilisation led to a 2-fold increase in the adjusted odds of discharge by 30-day postoperatively. We recommend inclusion of mobilisation within 36 h of surgery as a new UK Best Practice Tariff to help reduce delays to mobilisation currently experienced by one-fifth of patients surgically treated for hip fracture.

Identifying consistent biomechanical parameters across rising-to-walk subtasks to inform rehabilitation in practice: A systematic literature review

BACKGROUND

The best approach to rehabilitate the control of everyday whole-body movement (e.g. rise-to-walk) after pathology remains unclear in part because the associated controlled performance variables are not known. Rise-to-walk can be performed fluidly (sit-to-walk) or non-fluidly (sit-to-stand, proceeded by gait-initiation). Biomechanical variables that remain consistent in health regardless of how rise-to walk is performed represent controlled performance variable candidates which could monitor rehabilitative change.

RESEARCH QUESTION

To determine if any biomechanical parameters remain consistent across rising-to-walk (RTW) subtasks (sit-to-stand, gait-initiation, and sit-to-walk) in healthy adults for purposes of movement control assessment in clinical practice.

METHODS

Data sources included Medline, Cinahl, and Scopus databases, and the grey literature. Study selection was based on eligibility criteria and must have reported spatiotemporal, kinematic and/or kinetic biomechanical parameters featuring >1 RTW subtask. Data extraction and synthesis; standardised-mean-differences (SMDs) were calculated (pooled if replicated in >1 study) for each parameter. Consistency was determined if SMD95 %CIs included the zero-effect line.

RESULTS

Nine studies (n = 99) were included (40 ± 7.5yrs). Seven parameters were replicated in >1 study and subjected to meta-analysis (fixed-effect model). Two were consistent between sit-to-stand and sit-to-walk: flexion-momentum time (M(95 %CI) = 0.055(-0.423 to 0.533); p = 0.823) and peak whole-body-centre-of-mass vertical velocity (M(95 %CI)= -0.415(-0.898 to 0.069); p = 0.093); and centre-of-pressure to whole-body-centre-of-mass distance at toe-off (M(95 %CI)= -0.137(-0.712 to 0.439); p = 0.642) between gait-initiation and sit-to-walk. Another 20 parameters were consistent based on single-study SMDs.

SIGNIFICANCE

Consistent parameters might exist across RTW subtasks. However, the evidence is based on few studies with small samples and variable RTW protocols. Future studies designed to confirm consistency using a standardised RTW protocol are needed.

Gait-initiation onset estimation during sit-to-walk: Recommended methods suitable for healthy individuals and ambulatory community-dwelling stroke survivors

Background

Gait-initiation onset (GI-onset) during sit-to-walk (STW) is commonly defined by mediolateral ground-reaction-force (xGRF) rising and crossing a threshold pre-determined from sit-to-stand peak xGRF. However, after stroke this method [xGRFthresh] lacks validity due to impaired STW performance. Instead, methodologies based upon instance of swing-limb maximum-vertical-GRF [vGRFmaxSWING], maximum-xGRF [xGRFmax], and swing-limb heel-off [firstHEELoff] can be applied, although their validity is unclear. Therefore, we determined these methodologies’ validity by revealing the shortest transition-time (seat-off–GI-onset), their utility in routinely estimating GI-onset, and whether they exhibited satisfactory intra-subject reliability.

Methods

Twenty community-dwelling stroke (60 (SD 14) years), and twenty-one age-matched healthy volunteers (63 (13) years) performed 5 standardised STW trials with 2 force-plates and optical motion-tracking. Transition-time differences across-methods were assessed using Friedman tests with post-hoc pairwise-comparisons. Within-method single-measure intra-subject reliability was determined using ICC_3,1 and standard errors of measurement (SEMs).

Results

In the healthy group, median xGRFthresh transition-time was significantly shorter than xGRFmax (0.183s). In both the healthy and stroke groups, xGRFthresh transition-times (0.027s, 0.695s respectively) and vGRFmaxSWING (0.080s, 0.522s) were significantly shorter than firstHEELoff (0.293s, 1.085s) (p<0.001 in all cases). GI-onset failed to be estimated in 48% of stroke trials using xGRFthresh. Intra-subject variability was relatively high but was comparable across all estimation methods.

Conclusion

The firstHEELoff method yielded significantly longer transition-times. The xGRFthresh method failed to routinely produce an estimation of GI-onset estimation. Thus, with all methods exhibiting low, yet comparable intra-subject repeatability, averaged xGRFmax or vGRFmaxSWING repeated-measures are recommended to estimate GI-onset for both healthy and community-dwelling stroke individuals.

Reliability and feasibility of gait initiation centre-of-pressure excursions using a Wii® Balance Board in older adults at risk of falling

Background

Impairments in dynamic balance have a detrimental effect in older adults at risk of falls (OARF). Gait initiation (GI) is a challenging transitional movement. Centre of pressure (COP) excursions using force plates have been used to measure GI performance. The Nintendo Wii Balance Board (WBB) offers an alternative to a standard force plate for the measurement of CoP excursion.

Aims

To determine the reliability of COP excursions using the WBB, and its feasibility within a 4-week strength and balance intervention (SBI) treating OARF.

Methods

Ten OARF subjects attending SBI and ten young healthy adults, each performed three GI trials after 10 s of quiet stance from a standardised foot position (shoulder width) before walking forward 3 m to pick up an object. Averaged COP mediolateral (ML) and anteroposterior (AP) excursions (distance) and path-length time (GI-onset to first toe-off) were analysed.

Results

WBB ML (0.866) and AP COP excursion (0.895) reliability (ICC_3,1) was excellent, and COP path-length reliability was fair (0.517). Compared to OARF, healthy subjects presented with larger COP excursion in both directions and shorter COP path length. OARF subjects meaningfully improved their timed-up-and-go and ML COP excursion between weeks 1–4, while AP COP excursions, path length, and confidence-in-balance remained stable.

Discussion

COP path length and excursion directions probably measure different GI postural control attributes. Limitations in WBB accuracy and precision in transition tasks needs to be established before it can be used clinically to measure postural aspects of GI viably.

Conclusions

The WBB could provide valuable clinical evaluation of balance function in OARF.

Missed opportunities for physical activity management at key points throughout the chemotherapy pathway for colorectal survivors: an observational interview study

PURPOSE

Physical activity (PA) is central to self-management for people with colorectal cancer (CRC) to support health behaviour and function secondary to cancer treatment. However, there is limited evidence on how health professionals (HPs) promote PA during cancer treatment. This study aimed to investigate how and when PA is promoted throughout the chemotherapy pathway among colorectal cancer survivors.

METHODS

A qualitative study was conducted with adults with CRC receiving chemotherapy at a large cancer centre. Cross-sectional observation of clinical consultations was conducted at four points during the chemotherapy pathway: prior, midpoint, final cycle, and 8 weeks following chemotherapy. Following completion of treatment, audio-recorded, semi-structured interviews were conducted with patients and HPs and transcribed verbatim. Codes and themes were identified and triangulated from all the data using framework analysis. Observational themes are reported and complimented by interview data.

RESULTS

Throughout the chemotherapy pathway (pre, midpoint, end), many opportunities were missed by HPs to promote PA as a beneficial means to maintain functioning and ameliorate cancer treatment side effects. When discussed, PA levels were used only to determine fitness for future oncological treatment. No PA promotion was observed despite patients reporting low PA levels or treatment side effects. Post-treatment, PA promotion was more routinely delivered by HPs, as evidenced by problem-solving and onward referrals to relevant HPs.

CONCLUSION

PA promotion was largely absent during treatment despite it being a key component of patient self-management following treatment. This suggests considerable missed opportunities for HPs to provide cancer survivors with PA evidence-based interventions. Further research is necessary to identify how best to ensure PA is promoted throughout the cancer journey.

IMPLICATION FOR CANCER SURVIVORS

These findings suggest many may not be receiving support to be physically active during treatment.

Parameters that remain consistent independent of pausing before gait-initiation during normal rise-to-walk behaviour delineated by sit-to-walk and sit-to-stand-and-walk

BACKGROUND

Rising-to-walk is an everyday transitional movement task rarely employed in gait rehabilitation. Sit-to-walk (STW) and sit-to-stand-and-walk (STSW), where a pause separates sit-to-stand and gait-initiation (GI) represent extremes of rising-to-walk behaviour. Delayed GI can indicate pathological impairment but is also observed in healthy individuals. We hypothesise that healthy subjects express consistent biomechanical parameters, among others that differ, during successful rising-to-walk task performance regardless of behaviour. This study therefore sought to identify if any parameters are consistent between STW and STSW in health because they represent normal rise-to-walk performance independent of pause, and also because they represent candidate parameters sensitive enough to monitor change in pathology.

METHODS

Ten healthy volunteers performed 5 trials of STW and STSW. Event timing, ground-reaction-forces (GRFs), whole-body-centre-of-mass (BCoM) displacement, and centre-of-pressure (CoP) to extrapolated BCoM (xCoM) distance (indicator of positional stability) up to the 3rd step were compared between-tasks with paired t-tests. For consistent parameters; agreement between-tasks was assessed using Bland-Altman analyses and minimal-detectable-change (MDC) calculations.

RESULTS

Mean vertical GRFs, peak forward momentum and fluidity during rising; CoP-xCoM separation at seat-off, upright, GI-onset, and steps1-2; and forward BCoM velocity were all significantly greater in STW. In contrast, peak BCoM vertical momentum, flexion-momentum time, and 3rd step stability were consistent between tasks and yielded acceptable reliability.

CONCLUSION

STW is a more challenging task due to the merging of rising with GI reflected by greater CoP-xCoM separation compared to STSW indicative of more positional instability. However, BCoM vertical momentum, flexion-momentum time, and step3 stability remained consistent in healthy individuals and are therefore candidates with which to monitor change in gait rehabilitation following pathology. Future studies should impose typical pause-durations observed in pathology upon healthy subjects to determine if the parameters we have identified remain consistent.

Physical activity interventions are delivered consistently across hospitalized older adults but multimorbidity is associated with poorer rehabilitation outcomes: A population-based cohort study

BACKGROUND

Older adults live with multimorbidity including frailty and cognitive impairment often requiring hospitalization. While physical activity interventions (PAIs) are a normal rehabilitative treatment, their clinical effect in hospitalized older adults is uncertain.

OBJECTIVE

To observe PAI dosing characteristics and determine their impact on clinical performance parameters.

DESIGN

A single-site prospective observational cohort study in an older persons' unit.

SUBJECTS

Seventy-five older persons' unit patients ≥65 years.

INTERVENTION

PAI; therapeutic contact between physiotherapy clinician and patient.

MEASUREMENTS

Parameters included changes in activities-of-daily-living (Barthel Index), handgrip strength, balance confidence, and gait velocity, measured between admission and discharge (episode). Dosing characteristics were PAI temporal initiation, frequency, and duration. Frailty/cognition status was dichotomized independently per participant yielding 4 subgroups: frail/nonfrail and cognitively-impaired/cognitively-unimpaired.

RESULTS

Median (interquartile range) PAI initiation occurred after 2 days (1-4), frequency was 0.4 PAIs per day (0.3-0.5), and PAI duration per episode was 3.75 hours (1.8-7.2). All clinical parameters improved significantly across episodes: grip strength median (interquartile range) change, 2.0 kg (0.0-2.3) (P < .01); Barthel Index, 5 (3-8) (P < .01); gait velocity, 0.06 m.∙s^-1 (0.06-0.16) (P < .01); and balance confidence, -3 (-6 to -1) (P < .01). Physical activity intervention dosing remained consistent within subgroups. While several moderate to large associations between amount of PAIs and change in clinical parameters were observed, most were within unimpaired subgroups.

CONCLUSIONS

PAI dosing is consistent. However, while clinical changes during hospital episodes are positive, more favourable responses to PAIs occur if patients are nonfrail/cognitively-unimpaired. Therefore, to deliver a personalized rehabilitation approach, adaptation of PAI dose based on patient presentation is desirable.

Captivating a captive audience: a quality improvement project increasing participation in intradialytic exercise across five renal dialysis units

BACKGROUND

Benefits of exercise on dialysis (EOD) are well established, however, uptake in our local satellite haemodialysis units is low. The implications of the status quo are risks to treatment efficiency, equity and patient centredness in managing personal health risks. The current study aimed to identify and address barriers to exercise participation while on dialysis by substantiating local EOD risks, assigning context, implementing changes and evaluating their impact. Our primary objective was to increase the uptake of EOD across our five dialysis units.

METHODS

Semi-structured interview and questionnaire data from patients and nursing staff were used to inform a root-cause analysis of barriers to exercise participation while on dialysis. Intervention was subsequently designed and implemented by a senior physiotherapist. It consisted of patient and nursing staff education, equipment modification and introduction of patient motivation schemes.

RESULTS

Staff knowledge, patient motivation and equipment problems were the main barriers to EOD. A significant increase in the uptake of EOD from 23.3% pre-intervention to 74.3% post-intervention was achieved [χ2 (1, N = 174) = 44.18, P < 0.001].

CONCLUSIONS

Barriers to EOD are challenging, but there is evidence that patients wish to participate and would benefit from doing so. The input of a physiotherapist in the dialysis units had a significant positive effect on the uptake of EOD. National guidelines should encourage dialysis units to include professional exercise provision in future service planning.

Sit-to-stand-and-walk from 120% Knee Height: A Novel Approach to Assess Dynamic Postural Control Independent of Lead-limb

Individuals with sensorimotor pathology e.g., stroke have difficulty executing the common task of rising from sitting and initiating gait (sit-to-walk: STW). Thus, in clinical rehabilitation separation of sit-to-stand and gait initiation - termed sit-to-stand-and-walk (STSW) - is usual. However, a standardized STSW protocol with a clearly defined analytical approach suitable for pathological assessment has yet to be defined. Hence, a goal-orientated protocol is defined that is suitable for healthy and compromised individuals by requiring the rising phase to be initiated from 120% knee height with a wide base of support independent of lead limb. Optical capture of three-dimensional (3D) segmental movement trajectories, and force platforms to yield two-dimensional (2D) center-of-pressure (COP) trajectories permit tracking of the horizontal distance between COP and whole-body-center-of-mass (BCOM), the decrease of which increases positional stability but is proposed to represent poor dynamic postural control. BCOM-COP distance is expressed with and without normalization to subjects' leg length. Whilst COP-BCOM distances vary through STSW, normalized data at the key movement events of seat-off and initial toe-off (TO1) during steps 1 and 2 have low intra and inter subject variability in 5 repeated trials performed by 10 young healthy individuals. Thus, comparing COP-BCOM distance at key events during performance of an STSW paradigm between patients with upper motor neuron injury, or other compromised patient groups, and normative data in young healthy individuals is a novel methodology for evaluation of dynamic postural stability.

Sit-to-walk and sit-to-stand-and-walk task dynamics are maintained during rising at an elevated seat-height independent of lead-limb in healthy individuals

INTRODUCTION

Sit-to-walk (STW) is a common transitional motor task not usually included in rehabilitation. Typically, sit-to-stand (STS), pause, then gait initiation (GI) before walking is used, which we term sit-to-stand-and-walk (STSW). Separation between centre-of-pressure (COP) and whole-body centre-of-mass (BCOM) during GI is associated with dynamic postural stability. Rising from seats higher than knee-height (KH) is more achievable for patients, but whether this and/or lead-limb significantly affects task dynamics is unclear. This study tested whether rising from seat-heights and lead-limb affects STW and STSW task dynamics in young healthy individuals.

METHODS

Ten (5F) young (29±7.7 years) participants performed STW and STSW from a standardised position. Five trials of each task were completed at 100 and 120%KH leading with dominant and non-dominant legs. Four force-plates and optical motion capture delineated key movement events and phases with effect of seat-height and lead-limb determined by 2-way ANOVA within tasks.

RESULTS

At 120%KH, lower peak vertical ground-reaction-forces (vGRFs) and vertical BCOM velocities were observed during rising irrespective of lead-limb. No other parameters differed between seat-heights or lead-limbs. During GI in STSW there was more lateral, and less posterior, COP excursion than expected.

CONCLUSION

Reduction in vGRFs and velocity during rising at 120%KH is consistent with reduced effort in young healthy individuals and is likely therefore to be an appropriate seat-height for patients. Lead-limb had no effect upon STSW or STW parameters suggesting that normative data independent of lead-limb can be utilised to monitor motor rehabilitation should differences be observed in patients. STSW should be considered an independent movement transition.

Feasibility of using MIRA with adult patients presenting with upper limb motor dysfunction post neurological damage

Computer-based technology is an emerging modality to facilitate upper limb rehabilitation post neurological damage. A feasibility project using MIRA technology in an adult outpatient neurophysiotherapy service was conducted. Ten patients trialled nine MIRA games that promoted discrete and continuous unilateral and bilateral upper limb movements. The effect of MIRA use on usual service operation as well as any adverse events was noted. Patient views of using MIRA were explored through self-reported questionnaires. For six patients, comparison of amount and frequency of active upper limb exercises using MIRA and typical prescribed upper limb exercises was made. Use of MIRA did not negatively affect service operation and was not associated with any adverse event reporting. The majority of patients enjoyed using MIRA and felt that it was a useful modality to supplement existing prescribed upper limb exercises. Those with previous experience of technology expressed the most positive feedback. There is evidence that MIRA tasks may facilitate intensive repetitive upper limb movements, although some patients reported in-exercise discomfort. In conclusion, it was feasible to use MIRA with adult patients post neurological damage presenting with upper limb motor dysfunction, particularly those patients with proximal upper limb motor dysfunction previously familiar with computer use or gaming experience.

Clinical predictive value of manual muscle strength testing during critical illness: an observational cohort study

INTRODUCTION

Impaired skeletal muscle function has important clinical outcome implications for survivors of critical illness. Previous studies employing volitional manual muscle testing for diagnosing intensive care unit-acquired weakness (ICU-AW) during the early stages of critical illness have only provided limited data on outcome. This study aimed to determine inter-observer agreement and clinical predictive value of the Medical Research Council sum score (MRC-SS) test in critically ill patients.

METHODS

Study 1: Inter-observer agreement for ICU-AW between two clinicians in critically ill patients within ICU (n = 20) was compared with simulated presentations (n = 20). Study 2: MRC-SS at awakening in an unselected sequential ICU cohort was used to determine the clinical predictive value (n = 94) for outcomes of ICU and hospital mortality and length of stay.

RESULTS

Although the intra-class correlation coefficient (ICC) for MRC-SS in the ICU was 0.94 (95% CI 0.85-0.98), κ statistic for diagnosis of ICU-AW (MRC-SS <48/60) was only 0.60 (95% CI 0.25-0.95). Agreement for simulated weakness presentations was almost complete (ICC 1.0 (95% CI 0.99-1.0), with a κ statistic of 1.0 (95% CI 1.0-1.0)). There was no association observed between ability to perform the MRC-SS and clinical outcome and no association between ICU-AW and mortality. Although ICU-AW demonstrated limited positive predictive value for ICU (54.2%; 95% CI 39.2-68.6) and hospital (66.7%; 95% CI 51.6-79.6) length of stay, the negative predictive value for ICU length of stay was clinically acceptable (88.2%; 95% CI 63.6-98.5).

CONCLUSIONS

These data highlight the limited clinical applicability of volitional muscle strength testing in critically ill patients. Alternative non-volitional strategies are required for assessment and monitoring of muscle function in the early stages of critical illness.

On the fringes of conquest: maya-spanish contact in colonial belize

The defeat of the Aztecs of Mexico by Hernán Cortés in 1521 was but the beginning of a long and torturous conquest of Central America that did not always result in the mastery of people and production for which the Spanish had hoped. The Maya of the resource-poor Yucatán peninsula were spared the heavy colonial hand that held fast to central Mexico and its riches. In addition, the dense forests of the peninsula served as a haven for refugees fleeing oppressive conditions in colonial towns. Despite the paucity of documentary information on Maya communities of the frontier, knowledge of Maya-Spanish relations in the 16th and 17th centuries has advanced in recent years through archeological and ethnohistorical research. Work in one region of the Maya lowlands has brought us closer to an understanding of the early interaction of the rulers and the ruled.

Gamma-ray spectroscopy at the limits: first observation of rotational bands in 255Lr

The rotational band structure of 255Lr has been investigated using advanced in-beam gamma-ray spectroscopic techniques. To date, 255Lr is the heaviest nucleus to be studied in this manner. One rotational band has been unambiguously observed and strong evidence for a second rotational structure was found. The structures are tentatively assigned to be based on the 1/2-[521] and 7/2-[514] Nilsson states, consistent with assignments from recently obtained alpha decay data. The experimental rotational band dynamic moment of inertia is used to test self-consistent mean-field calculations using the Skyrme SLy4 interaction and a density-dependent pairing force.

Observation of a rotational band in the odd-Z transfermium nucleus 101251Md

A rotational band has been unambiguously observed in an odd-proton transfermium nucleus for the first time. An in-beam gamma-ray spectroscopic study of 101/251Md has been performed using the gamma-ray array JUROGAM combined with the gas-filled separator RITU and the focal plane device GREAT. The experimental results, compared to Hartree-Fock-Bogolyubov calculations, lead to the interpretation that the rotational band is built on the [521]1/2(-) Nilsson state.

Measurement of the sign of the spectroscopic quadrupole moment for the 2(1)+ state in 70Se: no evidence for oblate shape

Using a method whereby molecular and atomic ions are independently selected, an isobarically pure beam of 70Se ions was postaccelerated to an energy of 206 MeV using REX-ISOLDE. Coulomb-excitation yields for states in the beam and target nuclei were deduced by recording deexcitation gamma rays in the highly segmented MINIBALL gamma-ray spectrometer in coincidence with scattered particles in a silicon detector. At these energies, the Coulomb-excitation yield for the first 2+ state is expected to be strongly sensitive to the sign of the spectroscopic quadrupole moment through the nuclear reorientation effect. Experimental evidence is presented here for a prolate shape for the first 2+ state in 70Se, reopening the question over whether there are, as reported earlier, deformed oblate shapes near to the ground state in the light selenium isotopes.

Nuclear isomers in superheavy elements as stepping stones towards the island of stability

A long-standing prediction of nuclear models is the emergence of a region of long-lived, or even stable, superheavy elements beyond the actinides. These nuclei owe their enhanced stability to closed shells in the structure of both protons and neutrons. However, theoretical approaches to date do not yield consistent predictions of the precise limits of the 'island of stability'; experimental studies are therefore crucial. The bulk of experimental effort so far has been focused on the direct creation of superheavy elements in heavy ion fusion reactions, leading to the production of elements up to proton number Z = 118 (refs 4, 5). Recently, it has become possible to make detailed spectroscopic studies of nuclei beyond fermium (Z = 100), with the aim of understanding the underlying single-particle structure of superheavy elements. Here we report such a study of the nobelium isotope 254No, with 102 protons and 152 neutrons--the heaviest nucleus studied in this manner to date. We find three excited structures, two of which are isomeric (metastable). One of these structures is firmly assigned to a two-proton excitation. These states are highly significant as their location is sensitive to single-particle levels above the gap in shell energies predicted at Z = 114, and thus provide a microscopic benchmark for nuclear models of the superheavy elements.

Structure of the odd-A, shell-stabilized nucleus 253/102No

In-beam gamma-ray spectroscopic measurements have been made on 253/102No. A single rotational band was identified up to a probable spin of 39/2planck, which is assigned to the 7/2(+)[624] Nilsson configuration. The bandhead energy and the moment of inertia provide discriminating tests of contemporary models of the heaviest nuclei. Novel methods were required to interpret the sparse data set associated with cross sections of around 50 nb. These methods included comparisons of experimental and simulated spectra, as well as testing for evidence of a rotational band in the gammagamma matrix.

Conversion electron cascades in 254(102)No

The spectrum of prompt conversion electrons emitted by excited 254No nuclei has been measured, revealing discrete lines arising from transitions within the ground state band. A striking feature is a broad distribution that peaks near 100 keV and comprises high multiplicity electron cascades, probably originating from M1 transitions within rotational bands built on high K states.

Evaluation of phosphodiesterase I-based protocols for the detection of multiply damaged sites in DNA: the detection of abasic, oxidative and alkylative tandem damage in DNA oligonucleotides

It has been proposed that DNA multiply damaged sites (MDS), where more than one moiety in a local region ( approximately 1 helical turn, 10 bp) of the DNA is damaged, are lesions of enhanced biological significance. However, other than indirect measures, there are few analytical techniques that allow direct detection of MDS in DNA. In the present study we demonstrate the potential of protocols incorporating an exonucleolytic snake venom phosphodiesterase (SVPD) digestion stage to permit the direct detection of certain tandem damage, in which two lesions are immediately adjacent to each other on the same DNA strand. A series of prepared oligonucleotides containing either single or pairs of tetrahydrofuran moieties (F), thymine glycol lesions (T(g)) or methylphosphotriester adducts (Me-PTE) were digested with SVPD and the digests examined by either (32)P-end-labelling or electrospray mass spectrometry. The unambiguous observation of SVPD-resistant 'trimer' species in the digests of oligonucleotides containing adjacent F, T(g) and Me-PTE demonstrates that the SVPD digestion strategy is capable of allowing direct detection of certain tandem damage. Furthermore, in studies to determine the specificity of SVPD in dealing with pairs of lesions on the same strand, it was found mandatory to have the two lesions immediately adjacent to each other in order to generate the trimer species; pairs of lesions separated by as few as one or two normal nucleotides behave principally as single lesions towards SVPD.

Corn pollen deposition on milkweeds in and near cornfields

The density of corn pollen on leaves of milkweed plants inside and outside of cornfields was measured in several studies from different localities. The purpose was to obtain a representative picture of naturally occurring pollen densities to provide a perspective for laboratory and field studies of monarch larvae feeding on milkweed leaves with Bt corn pollen. Pollen density was highest (average 170.6 grains per cm(2)) inside the cornfield and was progressively lower from the field edge outward, falling to 14.2 grains per cm(2) at 2 m. Inside the cornfield, and for each distance from the field edge, a frequency distribution is presented showing the proportion of leaf samples with different pollen densities. Inside cornfields, 95% of leaf samples had pollen densities below 600 grains per cm(2) and the highest pollen density observed was 1400 grains per cm(2), which occurred in a study with a rainless anthesis period. All other studies had rainfall events during the anthesis period. A single rain event can remove 54-86% of the pollen on leaves. Leaves on the upper portion of milkweed plants, where young monarch larvae tend to feed, had only 30-50% of the pollen density levels of middle leaves.

Presence of benzo[a]pyrene diol epoxide adducts in target DNA leads to an increase in UV-induced DNA single strand breaks and supF gene mutations

Exposure to DNA damaging agents and mutagens often occurs as combinations of agents, or as complex mixtures of chemicals. We found that plasmid DNA adducted with benzo[a]pyrene diol epoxide (BPDE) was more susceptible to UV-induced single strand breaks than was control DNA. To determine whether the increase in DNA damage also applied to mutagenic lesions, the supF gene forward mutation assay was used to compare mutations induced by BPDE alone, UVB, UVC, BPDE followed by UVB and BPDE followed by UVC. It was found that the mutation frequency for BPDE + UVB (1167 in 10(4) transformants) was higher than BPDE alone (12 in 10(4) transformants) or UVB alone (446 in 10(4) transformants), and the mutation frequency for BPDE + UVC (197 in 10(4) transformants) was higher than BPDE alone or UVC alone (26 in 10(4) transformants). For BPDE + UVB and BPDE + UVC there was a significant increase in plasmids with multiple mutations. Whilst these indicate error prone repair due to the single strand breaks, the different mutation frequencies in plasmids treated to give similar levels of strand breaks suggest other mechanisms for the mutations in plasmids with single mutation events. The spectrum of non-multiple mutations in the two combined treatments included both UV signature mutations (GC-->AT as the most common mutation) and BPDE signature mutations (GC-->TA and GC-->CG as the most common mutations). However, the increase in absolute mutation frequency of BPDE signature mutations between BPDE treatment and BPDE + UV treatment was greater than the increase in absolute mutation frequency of UV signature mutations, even though the level of BPDE adducts was identical in each case. These results suggest two possibilities: (i) the BPDE adducts are photoactivated to a more mutagenic lesion, or (ii) the presence of UV lesions lead to the BPDE adducts becoming more mutagenic.

Characterization of DNA damage at purine residues in oligonucleotides and calf thymus DNA induced by the mutagen 1-nitrosoindole-3-acetonitrile

N-Nitrosoindoles can efficiently transfer the nitroso group to nucleophilic targets in isolated purine nucleotides, causing depurination, deamination, and the formation of a novel guanine analogue, oxanine [Lucas, L. T., Gatehouse, D., and Shuker, D. E. G. (1999) J. Biol. Chem. 274, 18319-18326]. To determine the likely biological relevance of these modification pathways, the reactivity of 1-nitrosoindole-3-acetonitrile (NIAN), a model 3-substituted N-nitrosoindole, with oligonucleotides and calf thymus DNA was examined at physiological pH and temperature. Reaction of NIAN with single-stranded oligonucleotides containing various guanine motifs resulted in the production of single-strand break products at guanine sites due to the formation of alkali-labile lesions. The number of lesions increased with NIAN concentration and incubation time. Modification of calf thymus DNA by NIAN resulted in depurination, which gave the corresponding purine bases, deamination coupled with depurination, which gave xanthine, and the formation of oxanine. The former pathway was clearly the most important, and all reaction products exhibited a dose-response relationship. Cytosine and thymine residues were inactive toward NIAN. Further studies revealed an additional product in NIAN-treated duplex DNA containing a CCGG motif that was characterized as an interstrand cross-link, the yield of which increased with increasing NIAN concentration. These results indicate that the transnitrosating ability of NIAN to modify purine residues is preserved at the macromolecular level, with guanine residues appearing to be a primary site of reaction. All of these modification processes are potentially mutagenic events if they occur in vivo.