Eocene animal trace fossils in 1.7-billion-year-old metaquartzites.

The Paleoproterozoic (1.7 Ga [billion years ago]) metasedimentary rocks of the Mount Barren Group in southwestern Australia contain burrows indistinguishable from ichnogenera Thalassinoides, Ophiomorpha, Teichichnus, and Taenidium, known from firmgrounds and softgrounds. The metamorphic fabric in the host rock is largely retained, and because the most resilient rocks in the sequence, the metaquartzites, are too hard for animal burrowing, the trace fossils have been interpreted as predating the last metamorphic event in the region. Since this event is dated at 1.2 Ga, this would bestow advanced animals an anomalously early age. We have studied the field relationships, petrographic fabric, and geochronology of the rocks and demonstrate that the burrowing took place during an Eocene transgression over a weathered regolith. At this time, the metaquartzites of the inundated surface had been weathered to friable sandstones or loose sands (arenized), allowing for animal burrowing. Subsequent to this event, there was a resilicification of the quartzites, filling the pore space with syntaxial quartz cement forming silcretes. Where the sand grains had not been dislocated during weathering, the metamorphic fabric was seemingly restored, and the rocks again assumed the appearance of hard metaquartzites impenetrable to animal burrowing.

The role of emotions in academic performance of undergraduate medical students: a narrative review.

BACKGROUND: This paper is devoted to a narrative review of the literature on emotions and academic performance in medicine. The review aims to examine the role emotions play in the academic performance of undergraduate medical students. METHODS: Eight electronic databases were used to search the literature from 2013 to 2023, including Academic Search Ultimate, British Education Index, CINAHL, Education Abstract, ERIC, Medline, APA Psych Articles and APA Psych Info. Using specific keywords and terms in the databases, 3,285,208 articles were found. After applying the predefined exclusion and inclusion criteria to include only medical students and academic performance as an outcome, 45 articles remained, and two reviewers assessed the quality of the retrieved literature; 17 articles were selected for the narrative synthesis. RESULT: The findings indicate that depression and anxiety are the most frequently reported variables in the reviewed literature, and they have negative and positive impacts on the academic performance of medical students. The included literature also reported that a high number of medical students experienced test anxiety during their study, which affected their academic performance. Positive emotions lead to positive academic outcomes and vice versa. However, Feelings of shame did not have any effect on the academic performance of medical students. DISCUSSION: The review suggests a significant relationship between emotions and academic performance among undergraduate medical students. While the evidence may not establish causation, it underscores the importance of considering emotional factors in understanding student performance. However, reliance on cross-sectional studies and self-reported data may introduce recall bias. Future research should concentrate on developing anxiety reduction strategies and enhancing mental well-being to improve academic performance.

Exploring the experience of working relationships for support workers of adults with intellectual disabilities.

BACKGROUND: Research suggests that a better awareness of how staff who directly support people with intellectual disabilities experience their working relationships, will contribute to understanding staff wellbeing and the quality of care they offer. This study aimed to gain insights into the lived experiences of support workers in supported living services in England. METHOD: Six support workers participated in semi-structured interviews, about their working relationships with service-users and colleagues. Data was analysed using interpretative phenomenological analysis. RESULTS: Six interconnected themes emerged: The essence of good relationships; a trusting relationship as the vehicle for meeting service-users' needs; belonging to the support team; the organisational context of relationships; the social context of relationships; 'a fine balancing act'. CONCLUSIONS: The findings provide insights into staff wellbeing, indicating that developing supportive, trusting relationships with both service-users and colleagues, plays an important role in delivering effective care. Potential implications for service providers are discussed.

Neurologists' lived experiences of communicating the diagnosis of a motor neurodegenerative condition: an interpretative phenomenological analysis.

BACKGROUND: Receiving the diagnosis of a motor neurodegenerative condition (MNDC) can be a life-changing experience. Although several studies of individuals' experiences have indicated dissatisfaction with aspects of how an MNDC diagnosis was communicated, few studies have addressed doctors' experiences of breaking bad news for these conditions, especially from a qualitative perspective. This study explored UK neurologists' lived experience of delivering an MNDC diagnosis. METHODS: Interpretative phenomenological analysis was used as the overarching method. Eight consultant neurologists working with patients with MNDCs took part in individual, semi-structured interviews. RESULTS: Two themes were constructed from the data: 'Meeting patients' emotional and information needs at diagnosis: a balancing act between disease, patient and organization-related factors', and 'Empathy makes the job harder: the emotional impact and uncovered vulnerabilities associated with breaking bad news'. Breaking the news of an MNDC diagnosis was challenging for participants, both in terms of achieving a patient-centred approach and in terms of dealing with their own emotions during the process. CONCLUSIONS: Based on the study's findings an attempt to explain sub-optimal diagnostic experiences documented in patient studies was made and how organizational changes can support neurologists with this demanding clinical task was discussed.

Exploring the validity of the body image scale with survivors of breast cancer: A cognitive interview approach.

OBJECTIVE: The aim of this study is to explore the construct validity of the Body Image Scale for Cancer Questionnaire (BIS) using cognitive interviews. METHODS: Twelve breast cancer survivors participated in a cognitive interview while completing the BIS. Each participant was asked to think-out-loud while answering items, and an interviewer asked probing questions relating to the participants' comprehension, example retrieval, certainty of answer and other decision-making factors. Interviews were audio recorded and transcribed, and the data were analysed deductively and inductively. RESULTS: The participants' interpretations of the questions varied significantly. Several participants perceived the phrasing of some questions to be leading. The participants were able to provide examples of how their physical, physiological and body function affected their body image. The participants expressed positive attitudes towards, and gratitude for their body, which was not captured by the questionnaire. At times, the participants felt uncertain in how to respond appropriately to specific items, and the participants found some items challenging to answer. Finally, the BIS included sensitive questions that elicited emotional reactions and discomfort for some participants. CONCLUSION: The findings of this study provide insight into, and suggestions for potential questionnaire revisions that may enhance the validity and relevance of the BIS for use with breast cancer survivors.

Staff compassion in acute mental health wards: a grounded theory investigation.

BACKGROUND: Staff working on acute inpatient mental health wards face unique challenges in terms of short admissions, acuity, complexity and exposure to violence, suicide and self-harm. They experience high levels of stress and burnout, which can impact compassion. AIM: To qualitatively explore staff's understanding and conceptualisation of the development, loss and restoration of compassion within acute inpatient environments. METHOD: Eleven participants from a variety of professional backgrounds currently working on acute wards were interviewed. Using constructivist grounded theory, data were synthesised into theoretical categories and sub-categories. RESULTS: A conceptual model of the facilitators and inhibitors of compassionate care was developed, based on five categories that emerged from the data: A compassionate stance; the challenges of acute wards; feeling under threat; restoring compassion; and a compassionate organisation. CONCLUSIONS: Findings outline the process whereby staff compassion can be challenged or depleted, leading to a negative appraisal of the patient. Colleague support, knowing and understanding patients, and accessing a reflective space all supported the restoration of compassion. Staff reported lack of organisational compassion influenced their ability to maintain a compassionate stance. The importance of appropriate training and support structures is discussed, alongside recommendations to support the development of compassionate acute mental health care.

Neurologists' current practice and perspectives on communicating the diagnosis of a motor neurodegenerative condition: a UK survey.

BACKGROUND: The communication of a life-changing diagnosis can be a difficult task for doctors with potential long-term effects on patient outcomes. Although several studies have addressed the experiences of individuals with motor neurodegenerative diseases in receiving this diagnosis, a significant research gap exists regarding professionals' perspectives, especially in the UK. This study aimed to assess UK neurologists' current practice and perspectives on delivering the diagnosis of a motor neurodegenerative disease, explore different aspects of the process and detail the potential challenges professionals might face. METHODS: We conducted an anonymised online survey with 44 questions, grouped into four sections; basic demographic information, current practice, the experience of breaking bad news and education and training needs. RESULTS: Forty-nine professionals completed the survey. Overall, participants seemed to meet the setting-related standards of good practice; however, they also acknowledged the difficulty of this aspect of their clinical work, with about half of participants (46.5%) reporting moderate levels of stress while breaking bad news. Patients' relatives were not always included in diagnostic consultations and participants were more reluctant to promote a sense of optimism to patients with poorer prognosis. Although professionals reported spending a mean of around 30-40 min for the communication of these diagnoses, a significant proportion of participants (21-39%) reported significantly shorter consultation times, highlighting organisational issues related to lack of capacity. Finally, the majority of participants (75.5%) reported not following any specific guidelines or protocols but indicated their interest in receiving further training in breaking bad news (78.5%). CONCLUSIONS: This was the first UK survey to address neurologists' practice and experiences in communicating these diagnoses. Although meeting basic standards of good practice was reported by most professionals, we identified several areas of improvement. These included spending enough time to deliver the diagnosis appropriately, including patients' relatives as a standard, promoting a sense of hope and responding to professionals' training needs regarding breaking bad news.

Experiences of clinical psychologists working in palliative care: A qualitative study.

BACKGROUND: Compassion fatigue refers to the emotional and physical exhaustion felt by professionals in caring roles, whereas compassion satisfaction encompasses the positive aspects of helping others. Levels of compassion satisfaction and fatigue have been found to be inconsistent in palliative care professionals, which could have serious implications for patients, professionals and organisations. OBJECTIVES: This study explored the experiences of clinical psychologists working in palliative care, all worked with adults with cancer, to gain an understanding of the impact this work has on their self and how they manage this. METHODS: A qualitative approach was taken, using semi-structured interviews and interpretative phenomenological analysis. RESULTS: Three superordinate themes were identified: commitment, existential impact on the self and the oracle. The participants' experiences were characterised by the relationship between themselves and their patients, the influence of working in palliative services on their world view and the impact of organisational changes. Differences between working as a clinical psychologist in palliative care versus non-palliative settings were considered. CONCLUSIONS: Professionals working in palliative care should be supported to reflect on their experiences of compassion and resilience, and services should provide resources that facilitate staff to practice positive self-care to maintain their well-being.

Musculoskeletal Preparticipation Physical Evaluation-Does it Lead to Decreased Musculoskeletal Morbidity?

A preparticipation physical evaluation (PPE) is a requirement that many athletes must complete before participating in organized sports. Currently, the traditional musculoskeletal (MSK) portion of the PPE lacks robust evidence to support its ability to accurately predict those at greater risk for MSK injury. Functional movement testing has garnered attention for potential use in the PPE having shown some promise for greater sensitivity at identifying those at greater risk for MSK injury. Despite the widespread use of MSK PPE screening to identify athletes at greater risk for MSK injury, there is no significant evidence demonstrating that subsequent interventions result in decreased MSK injury.

Deposition of 1.88-billion-year-old iron formations as a consequence of rapid crustal growth.

Iron formations are chemical sedimentary rocks comprising layers of iron-rich and silica-rich minerals whose deposition requires anoxic and iron-rich (ferruginous) sea water. Their demise after the rise in atmospheric oxygen by 2.32 billion years (Gyr) ago has been attributed to the removal of dissolved iron through progressive oxidation or sulphidation of the deep ocean. Therefore, a sudden return of voluminous iron formations nearly 500 million years later poses an apparent conundrum. Most late Palaeoproterozoic iron formations are about 1.88 Gyr old and occur in the Superior region of North America. Major iron formations are also preserved in Australia, but these were apparently deposited after the transition to a sulphidic ocean at 1.84 Gyr ago that should have terminated iron formation deposition, implying that they reflect local marine conditions. Here we date zircons in tuff layers to show that iron formations in the Frere Formation of Western Australia are about 1.88 Gyr old, indicating that the deposition of iron formations from two disparate cratons was coeval and probably reflects global ocean chemistry. The sudden reappearance of major iron formations at 1.88 Gyr ago--contemporaneous with peaks in global mafic-ultramafic magmatism, juvenile continental and oceanic crust formation, mantle depletion and volcanogenic massive sulphide formation--suggests deposition of iron formations as a consequence of major mantle activity and rapid crustal growth. Our findings support the idea that enhanced submarine volcanism and hydrothermal activity linked to a peak in mantle melting released large volumes of ferrous iron and other reductants that overwhelmed the sulphate and oxygen reservoirs of the ocean, decoupling atmospheric and seawater redox states, and causing the return of widespread ferruginous conditions. Iron formations formed on clastic-starved coastal shelves where dissolved iron upwelled and mixed with oxygenated surface water. The disappearance of iron formations after this event may reflect waning mafic-ultramafic magmatism and a diminished flux of hydrothermal iron relative to seawater oxidants.

The association between historical childhood sexual abuse and later parenting stress: a systematic review.

An individual's own experiences of childhood and being parented are likely to be key determinants of their later parenting experiences. Childhood sexual abuse (CSA) is arguably the most toxic experience to occur in childhood and therefore may be particularly likely to impact on parenting stress in the context of parenting one's own children. This paper aims to review studies investigating associations between earlier CSA and later parenting to determine the size and consistency of the effects, identify any mediators and moderators of the relationship, and assess the quality of the evidence base. PsycINFO, Academic Search Complete, CINAHL, MEDLINE, Web of Science, PubMed and PILOTS were searched from date of inception until 4th March 2016 and 14 studies met the inclusion criteria. Seven studies indicated a degree of direct association between experiencing CSA and later parenting stress, two studies found no association and five studies suggest that other variables such as locus of control and current stressors may affect the relationship between CSA and parenting stress. Additionally, 10 studies suggest an indirect relationship between CSA and parenting stress through current level of depression. Results suggest the existence of a relationship between CSA and parenting stress though this association is mostly mediated by other variables, including depression and other stressors. Clearer definitions of CSA and use of validated questionnaires are essential to progress this field of research.

Quality of doctor-patient communication through the eyes of the patient: variation according to the patient's educational level.

Good doctor-patient communication may lead to better compliance, higher patient satisfaction, and finally, better health. Although the social variance in how physicians and patients communicate is clearly demonstrated, little is known about what patients with different educational attainments actually prefer in doctor-patient communication. In this study we describe patients' perspective in doctor-patient communication according to their educational level, and to what extent these perspectives lean towards the expert opinion on doctor-patient communication. In a multi-center study (Belgium, The Netherlands, UK and Italy), focus group discussions were organised using videotaped medical consultations. A mixed methods approach was used to analyse the data. Firstly, a difference in perspective in communication style was found between the lower educated participants versus the middle and higher educated participants. Secondly, lower educated participants referred positively most to aspects related to the affective/emotional area of the medical consultation, followed by the task-oriented/problem-focused area. Middle and higher educated participants positively referred most to the task-oriented/problem-focused area. The competency of the physician was an important category of communication for all participants, independent of social background. The results indicate that the preferences of lower educated participants lean more towards the expert opinion in doctor-patient communication than the middle and higher educated participants. Patients' educational level seems to influence their perspective on communication style and should be taken into account by physicians. Further quantitative research is needed to confirm these results.

What do people appreciate in physicians' communication? An international study with focus groups using videotaped medical consultations.

BACKGROUND: The literature shows that the quality of communication is usually determined from a professional perspective. Patients or lay people are seldom involved in the development of quality indicators or communication. OBJECTIVE: To give voice to the lay people perspective on what constitutes 'good communication' by evoking their reactions to variations in physician communication. DESIGN: Lay people from four different countries watched the same videotaped standardized medical encounters and discussed their preferences in gender-specific focus groups who were balanced in age groups. SETTING AND PARTICIPANTS: Two hundred and fifty-nine lay people (64 NL, 72 IT, 75 UK and 48 BE) distributed over 35 focus groups of 6-8 persons each. MAIN VARIABLES STUDIED: Comments on doctors' behaviours were classified by the GULiVer framework in terms of contents and preferences. RESULTS: Participants prevalently discussed 'task-oriented expressions' (39%: competency, self-confident, providing solutions), 'affective oriented/emotional expressions' (25%: empathy, listening, reassuring) and 'process-oriented expressions' (23%: flexibility, summarizing, verifying). 'Showing an affective attitude' was most appreciated (positive percentage within category: 93%, particularly facilitations and inviting attitude), followed by 'providing solution' (85%). Among disfavoured behaviour, repetitions (88%), 'writing and reading' (54%) and asking permission (42%) were found. CONCLUSIONS: Although an affective attitude is appreciated by nearly everybody, people may vary widely in their communication needs and preferences: what is 'good communication' for one person may be disliked or even a source of irritation for another. A physician should be flexible and capable of adapting the consultation to the different needs of different patients. This challenges the idea of general communication guidelines.

The dragon and the snake: health practices among Chinese in the UK from an inter-disciplinary perspective.

OBJECTIVES: This paper explores how ethnicity has been represented in research on the health practices of Chinese populations in the UK and suggests ways in which such research might be enriched by adopting an interdisciplinary approach. DESIGN: A systematic literature review of studies was conducted on research with 'Chinese' in the UK. RESULTS: The review highlighted that research with Chinese populations is frequently grounded in assumptions about the homogeneity of Chinese ethnic and cultural identities, and health practices, which undermines the generalizability of findings and conclusions. CONCLUSIONS: There was a lack of clarity surrounding the term 'Chinese' as an ethnic and national label that can lead to racialised constructions of ethnicity. An interdisciplinary approach is a valuable tool for enriching understandings of culturally-specific accounts of health and illness, and to address ways in which Chinese populations negotiate different health care systems and models of health.

Reassessing the first appearance of eukaryotes and cyanobacteria.

The evolution of oxygenic photosynthesis had a profound impact on the Earth's surface chemistry, leading to a sharp rise in atmospheric oxygen between 2.45 and 2.32 billion years (Gyr) ago and the onset of extreme ice ages. The oldest widely accepted evidence for oxygenic photosynthesis has come from hydrocarbons extracted from approximately 2.7-Gyr-old shales in the Pilbara Craton, Australia, which contain traces of biomarkers (molecular fossils) indicative of eukaryotes and suggestive of oxygen-producing cyanobacteria. The soluble hydrocarbons were interpreted to be indigenous and syngenetic despite metamorphic alteration and extreme enrichment (10-20 per thousand) of (13)C relative to bulk sedimentary organic matter. Here we present micrometre-scale, in situ (13)C/(12)C measurements of pyrobitumen (thermally altered petroleum) and kerogen from these metamorphosed shales, including samples that originally yielded biomarkers. Our results show that both kerogen and pyrobitumen are strongly depleted in (13)C, indicating that indigenous petroleum is 10-20 per thousand lighter than the extracted hydrocarbons. These results are inconsistent with an indigenous origin for the biomarkers. Whatever their origin, the biomarkers must have entered the rock after peak metamorphism approximately 2.2 Gyr ago and thus do not provide evidence for the existence of eukaryotes and cyanobacteria in the Archaean eon. The oldest fossil evidence for eukaryotes and cyanobacteria therefore reverts to 1.78-1.68 Gyr ago and approximately 2.15 Gyr ago, respectively. Our results eliminate the evidence for oxygenic photosynthesis approximately 2.7 Gyr ago and exclude previous biomarker evidence for a long delay (approximately 300 million years) between the appearance of oxygen-producing cyanobacteria and the rise in atmospheric oxygen 2.45-2.32 Gyr ago.

Validating relationships among attachment, emotional intelligence and clinical communication.

CONTEXT: In a previous study, we found that emotional intelligence (EI) mediates the negative influences of Year 1 medical students' attachment styles on their provider-patient communication (PPC). However, in that study, students were examined on a relatively straightforward PPC skill set and were not assessed on their abilities to elicit relevant clinical information from standardised patients. The influence of these psychological variables in more demanding and realistic clinical scenarios warrants investigation. OBJECTIVES: This study aimed to validate previous research findings by exploring the mediating effect of EI on the relationship between medical students' attachment styles and their PPC across an ecologically valid PPC objective structured clinical examination (OSCE). METHODS: Year 2 medical students completed measures of attachment (the Experiences in Close Relationships-Short Form [ECR-SF], a 12-item measure which provides attachment avoidance and attachment anxiety dimensional scores) and EI (the Mayer-Salovey-Caruso Emotional Intelligence Test [MSCEIT], a 141-item measure on the perception, use, understanding and management of emotions), prior to their summative PPC OSCE. Provider-patient communication was assessed using OSCE scores. Structural equation modelling (SEM) was used to validate our earlier model of the relationships between attachment style, EI and PPC. RESULTS: A total of 296 of 382 (77.5%) students participated. Attachment avoidance was significantly negatively correlated with total EI scores (r = -0.23, p < 0.01); total EI was significantly positively correlated with OSCE scores (r = 0.32, p < 0.01). Parsimonious SEM confirmed that EI mediated the negative influence of attachment avoidance on OSCE scores. It significantly predicted 14% of the variance in OSCE scores, twice as much as the 7% observed in the previous study. CONCLUSIONS: In more demanding and realistic clinical scenarios, EI makes a greater contribution towards effective PPC. Attachment is perceived to be stable from early adulthood, whereas EI can be developed using targeted educational interventions. The validation of this theoretical model of PPC in Year 2 medical students strengthens the potential educational implications of EI.

Emotional intelligence in medical education: a critical review.

CONTEXT: Emotional intelligence (EI) is a term used to describe people's awareness of, and ability to respond to, emotions in themselves and other people. There is increasing research evidence that doctors' EI influences their ability to deliver safe and compassionate health care, a particularly pertinent issue in the current health care climate. OBJECTIVES: This review set out to examine the value of EI as a theoretical platform on which to base selection for medicine, communication skills education and professionalism. METHODS: We conducted a critical review with the aim of answering questions that clinical educators wishing to increase the focus on emotions in their curriculum might ask. RESULTS: Although EI seems, intuitively, to be a construct that is relevant to educating safe and compassionate doctors, important questions about it remain to be answered. Research to date has not established whether EI is a trait, a learned ability or a combination of the two. Furthermore, there are methodological difficulties associated with measuring EI in a medical arena. If, as has been suggested, EI were to be used to select for medical school, there would be a real risk of including and excluding the wrong people. CONCLUSIONS: Emotional intelligence-based education may be able to contribute to the teaching of professionalism and communication skills in medicine, but further research is needed before its wholesale adoption in any curriculum can be recommended.

'You're putting thoughts into my head': a qualitative study of the readiness of patients with breast, lung or prostate cancer to address emotional needs through the first 18 months after diagnosis.

OBJECTIVE: To investigate the readiness of patients to address emotional needs up to 18 months following a diagnosis of breast, lung or prostate cancer. METHOD: Patients (N = 42) attending pre-treatment, treatment and follow-up clinics were provided with information designed to help them manage their emotional reactions to cancer. Patients were interviewed 3-4 weeks later about their emotional experience of cancer and their attitudes towards managing emotional problems. Qualitative data analysis followed a constant comparative approach. RESULTS: Patients early in the cancer trajectory, who had not yet been engaged in chemotherapy or radiotherapy, described emotional distress as a temporary and understandable reaction that did not warrant professional intervention. They valued knowing that support was available, but did not want to use it, and were reluctant to acknowledge or address emotional needs. Conversely, patients currently or recently engaged in treatment readily acknowledged their emotional needs and welcomed help to address these. CONCLUSIONS: Drawing on social cognitive and other theories, we suggest that engagement in physical treatment and care allows patients to address emotional needs following a cancer diagnosis. Guidance that emotional needs should routinely be assessed and addressed at key points in the cancer trajectory should therefore be implemented cautiously when patients are only recently diagnosed; psychological intervention may be less appropriate at this time than later.

Exploring the relationships among attachment, emotional intelligence and communication.

OBJECTIVES: Attachment style has been shown to influence both emotional intelligence (EI) and the clinical communication of medical students and doctors. No research has assessed the relationships among attachment, EI and clinical communication in medical students. This study was conducted to evaluate the effect of EI on the relationship between medical students' attachment style and clinical communication. METHODS: Medical students were invited to complete measures of attachment (using the Experiences in Close Relationships-Short Form [ECR-SF], a 12-item measure that provides attachment avoidance and attachment anxiety dimensional scores) and EI (using the Mayer-Salovey-Caruso Emotional Intelligence Test [MSCEIT], a 141-item measure of the perception, use, understanding and management of emotions) at the end of Year 1, prior to a summative objective structured clinical examination (OSCE). Clinical communication was assessed using OSCE scores. Structural equation modelling (SEM) was used to analyse a hypothetical model of the relationships among attachment style, EI and clinical communication. RESULTS: A total of 200 of 358 (55.9%) students participated. Attachment avoidance was significantly negatively correlated with total EI scores (r=-0.28, p<0.01); total EI was significantly positively correlated with OSCE scores (r = 0.23, p < 0.01). A parsimonious SEM revealed that attachment avoidance accounted for 13% of the variance in students' total EI scores but did not directly predict OSCE scores, whereas total EI significantly predicted 7% of the variance in OSCE scores. CONCLUSIONS: Attachment is perceived to be stable from early adulthood, whereas the literature suggests that EI can be developed through the use of targeted interventions. This has potential implications for the training of medical students in clinical communication.

Identification and separation of protein, contaminant and substrate peaks using gentle-secondary ion mass spectrometry and the g-ogram.

RATIONALE: Secondary ion mass spectrometry (SIMS) is an important technique for the characterization of proteins at surfaces. However, interpretation of the mass spectra is complicated owing to confusion with peaks from contaminants and the substrate which is further compounded by complex fragmentation mechanisms. We test a new development of the G-SIMS method called the g-ogram to separate out spectral components without a priori information about which peaks to include in the analysis and which peaks relate to each component. METHODS: The effectiveness of the g-ogram method is investigated using a model system of lysozyme adsorbed onto a silicon wafer and indium tin oxide substrates. In the method, two SIMS spectra are acquired using Bi(+) and Mn(+) primary ions which create lower and higher fragmentation in the spectra, respectively. The g-ogram separates out components using a separation parameter that is related to the fragmentation energy. RESULTS: The g-ogram separates the spectrum of lysozyme adsorbed onto a silicon wafer into three components: (i) the substrate and PDMS contamination; (ii) a second, but unexpected, contaminant; and (iii) peaks from the protein amino acids. Similar results are achieved for the indium tin oxide substrate. In addition, evidence of fragments from plural amino acids with two candidate peaks at 140.12 Da and 185.08 Da is observed. CONCLUSIONS: The g-ogram method effectively separates out mass peaks relating to the substrate, contamination and protein without any a priori information or subjective decisions about which peaks to include in the analysis (so called 'peak picking'). This is a great help to analysts. We find two possible peaks from plural amino acids but no evidence of pluralities is found for peaks above 240 Da that are generated from when using Bi or Mn primary ions.