Older Patients with Advanced Chronic Kidney Disease and Their Perspectives on Prognostic Information: a Qualitative Study.

BACKGROUND: Prognostic information is key to shared decision-making, particularly in life-limiting illness like advanced chronic kidney disease (CKD). OBJECTIVE: To understand the prognostic information preferences expressed by older patients with CKD. DESIGN AND PARTICIPANTS: Qualitative study of 28 consecutively enrolled patients over 65 years of age with non-dialysis dependent CKD stages 3b-5, receiving care in a multi-disciplinary CKD clinic. APPROACH: Semi-structured telephone or in-person interviews to explore patients' preference for and perceived value of individualized prognostic information. Interviews were analyzed using inductive content analysis. KEY RESULTS: We completed interviews with 28 patients (77.7 ± SD 6.8 years, 69% men). Patients varied in their preference for prognostic information and more were interested in their risk of progression to end-stage kidney disease (ESKD) than in life expectancy. Many conflated ESKD risk with risk of death, perceiving a binary choice between dialysis and quick decline and death. Patients expressed that prognostic information would allow them to plan, take care of important business, and think about their treatment options. Patients were accepting of prognostic uncertainty and imagined leveraging it to nurture hope or motivate them to better manage risk factors. They endorsed the desire to receive prognosis of life expectancy even though it may be hard to accept or difficult to talk about but worried it could create helplessness for other patients in their situation. CONCLUSION: Most, but not all, patients were interested in prognostic information and could see its value in motivating behavior change and allowing planning. Some patients expressed concern that information on life expectancy might cause depression and hopelessness. Therefore, prognostic information is most appropriate as part of a clinical conversation that fosters shared decision-making and helps patients consider treatment risks, benefits, and burdens in context of their lives.

Capacity Building Together: Shifting Roles for Research and Implementation in Health Resilience Among American Indians in Arizona.

Community engagement has become a leading framework for supporting health equity. The process of engagement includes groups working together to continually identify and erode existing inequalities to promote a justice-oriented approach to health and wellness for all. Missing from the literature is a fine-grained study of processes that occur between and among project partners building the foundation for ongoing trust and reciprocity. Our project, Health Resilience among American Indians in Arizona, brought new and seasoned researchers together to collect and analyze data on healthcare provider knowledge and American Indian resilience. Four years after the conclusion of the project, central members of the team developed a postproject self-assessment to investigate lasting impacts of project participation using what we call an "Iterative Poly-knowledge Evaluation Cycle approach." Results highlight the value of flexibility of roles and organic change within projects, the importance of a focus on strengths rather than deficits, and the identification of lasting change on project team members at all levels to build and bolster multisectoral scaffolding for partnerships for health. We present this case study to contribute to an understanding of impacts of community-engaged, Indigenous research projects on people who work together toward challenging existing systems of inequality for better community health.

Equal, global, local: discourses in Taiwan's international medical graduate debate.

CONTEXT: With the globalisation of medicine, the role of international medical graduates (IMGs) has expanded. Nonetheless, the experiences of native-born IMGs remain under-researched. In Taiwan, public controversy has unfolded around IMGs educated in Poland, calling into question the meaning(s) of equality in policy and medicine. In focusing on the return of IMGs to their countries of origin, this study adds to the growing literature concerning equality and globalisation in medical education. OBJECTIVES: The primary research aim was to analyse how stakeholders in the IMG debate use equality in their arguments. The authors set out to frame the dispute within the recent history of Taiwanese medical governance. An overarching objective was to contribute a critical, historical view of how discourses of globalisation and equality construct different policy approaches to international medical education. METHODS: The authors performed a critical discourse analysis of a public policy dispute in Taiwan, assembling an archive from online interactions, government reports and news articles. Coding focused on stakeholders' uses of equality to generate broader discourses. RESULTS: International and domestic Taiwanese students conceived of equality differently, referencing both 'equality of opportunity' and 'equality of outcome' within localisation and globalisation frameworks, respectively. The dominance of localisation discourse is reflected in hostile online rhetoric towards Poland-educated IMGs. CONCLUSIONS: Rhetorical disagreements over equality in medical education trace shifting state policies, from earlier attempts to remove barriers for IMGs to the present-day push to regulate IMGs for acculturation and quality assurance. The global Internet had a double-sided influence, facilitating both democratic political mobilization and the spread of hate speech. The policy debate in Taiwan mirrors discourses in Canada, where IMGs are likewise conceived either as globally competent physicians or as lacking in merit and technical competence. Future research could investigate the discursive formation and evidential basis of policies regulating international medical education.

Magnetic resonance imaging cervical spine in trauma: A retrospective single-centre audit of patient outcomes.

OBJECTIVE: Magnetic resonance imaging (MRI) is often used in practice to investigate for cord or discoligamentous injury following blunt trauma and a normal computed tomography (CT). This study investigates the MRI findings and surgical outcomes of patients in this cohort. METHODS: Retrospective analysis of patients following trauma with suspected cervical spine injury from 2016 to 2019. Inclusion criteria included patients receiving a normal CT of the cervical spine and subsequent MRI due to cervical spine injury symptomatology (persistent tenderness and/or neurology). Inclusion criteria included: age ≥16 years, alert and <72 h from CT to MRI. Mann-Whitney and χ2 statistical analysis techniques were employed. RESULTS: Two hundred and twenty-eight patients with persistent midline tenderness and/or persistent neurology following blunt trauma and negative CT report were included. One hundred and eighty-one patients received an MRI for persistent tenderness of which 35 revealed abnormal MRI findings. Twenty-one cases required no treatment, 14 cases were treated with a rigid collar with no patients requiring operative management. Forty-seven patients received an MRI for neurological symptoms following blunt trauma and negative CT, with 11 abnormal MRI findings. Management included no treatment (three cases), application of rigid collar (six cases) and operative management (two cases). CONCLUSION: No alert neurologically intact patient with 'persistent tenderness only' received operative management following a normal CT examination. While MRI is sensitive for detecting soft tissue injuries, the prevalence for detecting clinically significant cervical spine injury in blunt trauma patients in the absence of neurology is low. The utility of MRI in this cohort is questionable considering prolonged spinal immobilisation is not without harm.

Information-seeking behaviours and uncertainty around accessing primary care in the changing landscape of the COVID-19 pandemic: a qualitative study.

BACKGROUND: The COVID-19 pandemic has had and will continue to have a disproportionate effect on the most vulnerable. Public health messaging has been vital to mitigate the impact of the pandemic, but messages intended to slow the transmission of the virus may also cause harm. Understanding the areas where public health messaging could be improved may help reduce this harm. AIM: To explore and understand health communication issues faced by those most likely to be impacted by the COVID-19 pandemic. DESIGN & SETTING: A qualitative study using online surveys. The area of focus was Fife, a local authority in Scotland, UK. METHOD: Two consecutive surveys were conducted. Survey 1 explored the observations of support workers and Facebook group moderators, and focused on key issues faced by service users, as well as examples of good practice (n = 19). Survey 2 was aimed at community members, and focused on issues regarding access to and communication around access to primary care (n = 34). RESULTS: Survey 1 found broad issues around communication and access to primary care services. Survey 2 emphasised key issues in accessing primary care, including: (a) the lengthy process of making appointments; (b) feeling like a burden for wanting to be seen; (c) a lack of confidence in remote triaging and consultations; and (d) not knowing what to expect before getting an appointment. CONCLUSION: Clear issues regarding access to primary care were identified. The new understanding of these issues will inform a co-creation process designed to develop clear, actionable, and effective public health messages centred on improving access to primary care.

Factors that influence Cape fur seal predation on Cape gannets at Lambert's Bay, South Africa.

Seabird populations experience predation that can impact their breeding density and breeding success. The Cape gannet Morus capensis is endemic to the Benguela upwelling ecosystem and is classified as Endangered by the IUCN. They are affected by several threats, including predation by the Cape fur seal Arctocephalus pusillus pusillus. Many fledglings succumb to predation during their maiden flight across waters around the island. To curb predation, the selective culling of individual predatory seals was implemented in 2014, 2015, and 2018. Our first study objective was to determine if selective culling of Cape fur seals significantly reduced predation probability on Cape gannets. We tested whether predation probability in 2014, 2015, and 2018 was affected by fish biomass, gannet fledgling numbers, and/or the presence/absence of selective culling. Our second objective was to determine what led to fluctuations in Cape fur seal predation on Cape gannet fledglings between 2007 and 2018. We tested whether fish biomass and the amount of Cape gannet fledglings in the water affected predation probability on the fledglings. Results indicated that selective culling reduced predation within years. We found that with both increased fledgling numbers and increased fish biomass, seal predation probability was reduced. This suggests that a sustainable way to promote the conservation of Cape gannets would be to increase food availability for both the Cape fur seals and Cape gannets. Our findings, collectively with the global trend of the declining Cape gannet population and their endemism, provide reasons advocating for the conservation of the food resources of both the Cape fur seal and the Cape gannet in the Benguela system.

Paths of Emergency Department Care: Development of a Decision Aid to Facilitate Shared Decision Making in Goals of Care Discussions in the Acute Setting.

BACKGROUND: Goals of care (GOC) conversations in the emergency department (ED) are often a brief discussion of code status rather than a patient-oriented dialogue. We aimed to develop a guide to facilitate conversations between ED clinicians and patients to elicit patient values and establish goals for end-of-life care, while maintaining ED efficiency. Paths of ED Care, a conversation guide, is the product of this work. DESIGN: A multidisciplinary/multispecialty group used recommended practices to adapt a GOC conversation guide for ED patients. ED clinicians used the guide and provided feedback on content, design, and usability. Patient-clinician interactions were recorded for discussion analysis, and both were surveyed to inform iterative refinement. A series of discussions with patient representatives, multidisciplinary clinicians, bioethicists, and health care designers yielded feedback. We used a process similar to the International Patient Decision Aid Standards and provide comparison to these. RESULTS: A conversation guide, eight pages with each page 6 by 6 inches in dimension, uses patient-oriented prompts and includes seven sections: 1) evaluation of patient/family understanding of disease, 2) explanation of possible trajectories, 3) introduction to different pathways of care, 4) explanation of pathways, 5) assessment of understanding and concerns, 6) code status, and 7) personalized summary. LIMITATIONS: Recruitment of sufficient number of patients/providers to the project was the primary limitation. Methods are limited to qualitative analysis of guide creation and feasibility without quantitative analysis. CONCLUSIONS: Paths of ED Care is a guide to facilitate patient-centered shared decision making for ED patients, families, and clinicians regarding GOC. This may ensure care concordant with patients' values and preferences. Use of the guide was well-received and facilitated meaningful conversations between patients and providers.

Building a Narrative of Equity: Weaving Indigenous Approaches into Community-Engaged Research.

In 2020, global injustice has taken center stage during the uprising of the Black Lives Matter movement and other social movements. Activists are calling attention to longstanding disparities in health outcomes and an urgent need for justice. Given the global socio-political moment, how can health researchers draw on current critical theory and social movements to create structures for equitable outcomes in health research and practice? Here, we demonstrate principles for effective health research and social justice work that builds on community-engaged approaches by weaving critical Indigenous approaches into structural project designs. Our project, "Health Resilience among American Indians in Arizona", brought new and seasoned researchers together to collect and analyze data on the knowledge of healthcare providers concerning American Indian health and well-being. Four years after the conclusion of the project, the team developed and created a post-project self-assessment to investigate lasting impacts of project participation. In this communication, we discuss the principles of defining and measuring the capacity to build together. This work responds to the call from Indigenous scholars and community leaders to build an internal narrative of change. While we will not present the full instrument, we will discuss building a strong foundation using the principles of engagement for planning and implementing justice and change.

The histone and non-histone methyllysine reader activities of the UHRF1 tandem Tudor domain are dispensable for the propagation of aberrant DNA methylation patterning in cancer cells.

The chromatin-binding E3 ubiquitin ligase ubiquitin-like with PHD and RING finger domains 1 (UHRF1) contributes to the maintenance of aberrant DNA methylation patterning in cancer cells through multivalent histone and DNA recognition. The tandem Tudor domain (TTD) of UHRF1 is well-characterized as a reader of lysine 9 di- and tri-methylation on histone H3 (H3K9me2/me3) and, more recently, lysine 126 di- and tri-methylation on DNA ligase 1 (LIG1K126me2/me3). However, the functional significance and selectivity of these interactions remain unclear. In this study, we used protein domain microarrays to search for additional readers of LIG1K126me2, the preferred methyl state bound by the UHRF1 TTD. We show that the UHRF1 TTD binds LIG1K126me2 with high affinity and selectivity compared to other known methyllysine readers. Notably, and unlike H3K9me2/me3, the UHRF1 plant homeodomain (PHD) and its N-terminal linker (L2) do not contribute to multivalent LIG1K126me2 recognition along with the TTD. To test the functional significance of this interaction, we designed a LIG1K126me2 cell-penetrating peptide (CPP). Consistent with LIG1 knockdown, uptake of the CPP had no significant effect on the propagation of DNA methylation patterning across the genomes of bulk populations from high-resolution analysis of several cancer cell lines. Further, we did not detect significant changes in DNA methylation patterning from bulk cell populations after chemical or genetic disruption of lysine methyltransferase activity associated with LIG1K126me2 and H3K9me2. Collectively, these studies identify UHRF1 as a selective reader of LIG1K126me2 in vitro and further implicate the histone and non-histone methyllysine reader activity of the UHRF1 TTD as a dispensable domain function for cancer cell DNA methylation maintenance.

Determining the conformational stability of a protein using urea denaturation curves.

The stability of globular proteins is an important factor in determining their usefulness in basic research and medicine. A number of environmental factors contribute to the conformational stability of a protein, including pH, temperature, and ionic strength. In addition, variants of proteins may show remarkable differences in stability from their wild-type form. In this chapter, we describe the method and analysis of urea denaturation curves to determine the conformational stability of a protein. This involves relatively simple experiments that can be done in a typical biochemistry laboratory, especially when using ordinary spectroscopic techniques to follow unfolding.

Changing conversations in primary care for patients living with chronic conditions: pilot and feasibility study of the ICAN Discussion Aid.

PURPOSE: To pilot test the impact of the ICAN Discussion Aid on clinical encounters. METHODS: A pre-post study involving 11 clinicians and 100 patients was conducted at two primary care clinics within a single health system in the Midwest. The study examined clinicians' perceptions about ICAN feasibility, patients' and clinicians' perceptions about encounter success, videographic differences in encounter topics, and medication adherence 6 months after an ICAN encounter. RESULTS: 39/40 control encounters and 45/60 ICAN encounters yielded usable data. Clinicians reported ICAN use was feasible. In ICAN encounters, patients discussed diet, being active and taking medications more. Clinicians scored themselves poorer regarding visit success than their patients scored them; this effect was more pronounced in ICAN encounters. ICAN did not improve 6-month medication adherence or lengthen visits. CONCLUSION: This pilot study suggests that using ICAN in primary care is feasible, efficient and capable of modifying conversations. With lessons learned in this pilot, we are conducting a randomised trial of ICAN versus usual care in diverse clinical settings. TRIAL REGISTRATION NUMBER: NCT02390570.

Purposeful SDM: A problem-based approach to caring for patients with shared decision making.

OBJECTIVE: Patient involvement focused the growth of Shared Decision Making (SDM) in contemporary healthcare practice, research, and education. Whilst important, securing appropriate patient involvement or equipping patients to choose is not necessarily the principal purpose of SDM. The purpose of SDM like all medical decision making is to act well in response to a patient's problem, broadly conceived. In which situations and how SDM addresses patient problems is unclear. We seek to develop a purposeful approach to SDM that is oriented to the kinds of problems that SDM might help resolve. METHODS: Through vignettes of the experience of a patient, Rachel we demonstrate different kinds of situations in which Rachel, her family, and clinicians need to make decisions together. RESULTS: Different methods of SDM are needed in situations of: CONCLUSION: SDM may be understood as a range of methods that vary substantially with patients' situations and the purpose that they pursue. PRACTICE IMPLICATIONS: Clinicians struggle to adopt SDM when they do not see it as relevant to clinical work. Orienting SDM to the problems that patients and clinicians routinely face may further SDM adoption, education, and research.

A functional proteomics platform to reveal the sequence determinants of lysine methyltransferase substrate selectivity.

Lysine methylation is a key regulator of histone protein function. Beyond histones, few connections have been made to the enzymes responsible for the deposition of these posttranslational modifications. Here, we debut a high-throughput functional proteomics platform that maps the sequence determinants of lysine methyltransferase (KMT) substrate selectivity without a priori knowledge of a substrate or target proteome. We demonstrate the predictive power of this approach for identifying KMT substrates, generating scaffolds for inhibitor design, and predicting the impact of missense mutations on lysine methylation signaling. By comparing KMT selectivity profiles to available lysine methylome datasets, we reveal a disconnect between preferred KMT substrates and the ability to detect these motifs using standard mass spectrometry pipelines. Collectively, our studies validate the use of this platform for guiding the study of lysine methylation signaling and suggest that substantial gaps exist in proteome-wide curation of lysine methylomes.

The "Glocalization" of Medical School Accreditation: Case Studies From Taiwan, South Korea, and Japan.

PURPOSE: In an age of globalized medical education, medical school accreditation has been hailed as an approach to external quality assurance. However, accreditation standards can vary widely across national contexts. To achieve recognition by the World Federation for Medical Education (WFME), national accrediting bodies must develop standards suitable for both local contexts and international recognition. This study framed this issue in terms of "glocalization" and aimed to shine light on this complicated multistakeholder process by exploring accreditation in Taiwan, South Korea, and Japan. METHOD: This study employed a comparative case-study design, examining the national standards that three accreditation bodies in East Asia developed using international reference standards. In 2015-2016, the authors conducted document analysis of the English versions of the standards to identify the differences between the national and international reference standards as well as how and why external standards were adapted. RESULTS: Each country's accreditation body sought to balance local needs with global demands. Each used external standards as a template (e.g., Liaison Committee on Medical Education, General Medical Council, or WFME standards) and either revised (Taiwan, South Korea) or annotated (Japan) the standards to fit the local context. Four categories of differences emerged to account for how and why national standards departed from external references: structural, regulatory, developmental, and aspirational. CONCLUSIONS: These countries' glocalization of medical accreditation standards serve as examples for others seeking to bring their accreditation practices in line with global standards while ensuring that local values and societal needs are given adequate consideration.

Asp79 makes a large, unfavorable contribution to the stability of RNase Sa.

The two most buried carboxyl groups in ribonuclease Sa (RNase Sa) are Asp33 (99% buried; pK 2.4) and Asp79 (85% buried; pK 7.4). Above these pK values, the stability of the D33A variant is 6kcal/mol less than wild-type RNase Sa, and the stability of the D79A variant is 3.3kcal/mol greater than wild-type RNase Sa. The key structural difference between the carboxyl groups is that Asp33 forms three intramolecular hydrogen bonds, and Asp79 forms no intramolecular hydrogen bond. Here, we focus on Asp79 and describe studies of 11 Asp79 variants. Most of the variants were at least 2kcal/mol more stable than wild-type RNase Sa, and the most interesting was D79F. At pH 3, below the pK of Asp79, RNase Sa is 0.3kcal/mol more stable than the D79F variant. At pH 8.5, above the pK of Asp79, RNase Sa is 3.7kcal/mol less stable than the D79F variant. The unfavorable contribution of Asp79 to the stability appears to result from the Born self-energy of burying the charge and, more importantly, from unfavorable charge-charge interactions. To counteract the effect of the negative charge on Asp79, we prepared the Q94K variant and the crystal structure showed that the amino group of the Lys formed a hydrogen-bonded ion pair (distance, 2.71A; angle, 100 degrees ) with the carboxyl group of Asp79. The stability of the Q94K variant was about the same as the wild-type at pH 3, where Asp79 is uncharged, but 1kcal/mol greater than that of wild-type RNase Sa at pH 8.5, where Asp79 is charged. Differences in hydrophobicity, steric strain, Born self-energy, and electrostatic interactions all appear to contribute to the range of stabilities observed in the variants. When it is possible, replacing buried, non-hydrogen bonded, ionizable side-chains with non-polar side-chains is an excellent means of increasing protein stability.

Contextualizing the Physician Charter on Professionalism in Qatar: From Patient Autonomy to Family Autonomy.

BACKGROUND: The Physician Charter on medical professionalism has been endorsed by professional organizations worldwide, yet it is unclear if this Western framework of professionalism is applicable in non-Western countries. OBJECTIVE: This study examines how physicians practicing in a Middle Eastern context perceive the terms, principles, and commitments outlined in the charter. METHODS: In May 2013, the authors conducted 6 focus groups with 43 clinician-educators practicing at Hamad Medical Corporation in Doha, Qatar, to discuss the applicability of the Physician Charter in a local context. The research team coded and analyzed transcripts to identify sociocultural influences on professionalism. RESULTS: Participants generally expressed agreement with the applicability of the charter's principles to physician professionalism in Qatar. However, 3 contextual factors (religious beliefs and practices, family-centered decision making, and multinationality) complicated the application of the core principles of patient autonomy and social justice. Islamic beliefs reinforced the importance of professional values such as altruism, but presented a barrier to the principle of self-determination for female patients. The family-centered culture in Qatar called for enlarging the scope of patient-centered decision making to include the patient's family. Qatar's multinational population prompted debate over equal treatment and how to conceptualize and implement the principle of social justice. CONCLUSIONS: Several sociocultural contexts influence the conceptualization of the principles of medical professionalism in Qatar. The findings suggest that contextual factors should be considered when developing or adopting a professionalism framework in an international setting and context.

Charge-charge interactions are key determinants of the pK values of ionizable groups in ribonuclease Sa (pI=3.5) and a basic variant (pI=10.2).

The pK values of the titratable groups in ribonuclease Sa (RNase Sa) (pI=3.5), and a charge-reversed variant with five carboxyl to lysine substitutions, 5K RNase Sa (pI=10.2), have been determined by NMR at 20 degrees C in 0.1M NaCl. In RNase Sa, 18 pK values and in 5K, 11 pK values were measured. The carboxyl group of Asp33, which is buried and forms three intramolecular hydrogen bonds in RNase Sa, has the lowest pK (2.4), whereas Asp79, which is also buried but does not form hydrogen bonds, has the most elevated pK (7.4). These results highlight the importance of desolvation and charge-dipole interactions in perturbing pK values of buried groups. Alkaline titration revealed that the terminal amine of RNase Sa and all eight tyrosine residues have significantly increased pK values relative to model compounds.A primary objective in this study was to investigate the influence of charge-charge interactions on the pK values by comparing results from RNase Sa with those from the 5K variant. The solution structures of the two proteins are very similar as revealed by NMR and other spectroscopic data, with only small changes at the N terminus and in the alpha-helix. Consequently, the ionizable groups will have similar environments in the two variants and desolvation and charge-dipole interactions will have comparable effects on the pK values of both. Their pK differences, therefore, are expected to be chiefly due to the different charge-charge interactions. As anticipated from its higher net charge, all measured pK values in 5K RNase are lowered relative to wild-type RNase Sa, with the largest decrease being 2.2 pH units for Glu14. The pK differences (pK(Sa)-pK(5K)) calculated using a simple model based on Coulomb's Law and a dielectric constant of 45 agree well with the experimental values. This demonstrates that the pK differences between wild-type and 5K RNase Sa are mainly due to changes in the electrostatic interactions between the ionizable groups. pK values calculated using Coulomb's Law also showed a good correlation (R=0.83) with experimental values. The more complex model based on a finite-difference solution to the Poisson-Boltzmann equation, which considers desolvation and charge-dipole interactions in addition to charge-charge interactions, was also used to calculate pK values. Surprisingly, these values are more poorly correlated (R=0.65) with the values from experiment. Taken together, the results are evidence that charge-charge interactions are the chief perturbant of the pK values of ionizable groups on the protein surface, which is where the majority of the ionizable groups are positioned in proteins.

Changing the net charge from negative to positive makes ribonuclease Sa cytotoxic.

Ribonuclease Sa (pI = 3.5) from Streptomyces aureofaciens and its 3K (D1K, D17K, E41K) (pI = 6.4) and 5K (3K + D25K, E74K) (pI = 10.2) mutants were tested for cytotoxicity. The 5K mutant was cytotoxic to normal and v-ras-transformed NIH3T3 mouse fibroblasts, but RNase Sa and 3K were not. The structure, stability, and activity of the three proteins are comparable, but the net charge at pH 7 increases from -7 for RNase Sa to -1 for 3K and to +3 for 5K. These results suggest that a net positive charge is a key determinant of ribonuclease cytotoxicity. The cytotoxic 5K mutant preferentially attacks v-ras-NIH3T3 fibroblasts, suggesting that mammalian cells expressing the ras-oncogene are potential targets for ribonuclease-based drugs.

Contribution of active site residues to the activity and thermal stability of ribonuclease Sa.

We have used site-specific mutagenesis to study the contribution of Glu 74 and the active site residues Gln 38, Glu 41, Glu 54, Arg 65, and His 85 to the catalytic activity and thermal stability of ribonuclease Sa. The activity of Gln38Ala is lowered by one order of magnitude, which confirms the involvement of this residue in substrate binding. In contrast, Glu41Lys had no effect on the ribonuclease Sa activity. This is surprising, because the hydrogen bond between the guanosine N1 atom and the side chain of Glu 41 is thought to be important for the guanine specificity in related ribonucleases. The activities of Glu54Gln and Arg65Ala are both lowered about 1000-fold, and His85Gln is totally inactive, confirming the importance of these residues to the catalytic function of ribonuclease Sa. In Glu74Lys, k(cat) is reduced sixfold despite the fact that Glu 74 is over 15 A from the active site. The pH dependence of k(cat)/K(M) is very similar for Glu74Lys and wild-type RNase Sa, suggesting that this is not due to a change in the pK values of the groups involved in catalysis. Compared to wild-type RNase Sa, the stabilities of Gln38Ala and Glu74Lys are increased, the stabilities of Glu41Lys, Glu54Gln, and Arg65Ala are decreased and the stability of His85Gln is unchanged. Thus, the active site residues in the ribonuclease Sa make different contributions to the stability.

Patients at low risk for periprocedural myocardial infarction can be identified by assessment immediately following percutaneous coronary intervention.

Despite utilizing optimal anticoagulant therapy during percutaneous coronary intervention (PCI), the incidence of periprocedural myocardial infarction (PPMI) remains 5 7% and evaluation of preprocedural clinical/angiographic characteristics has failed to reliably predict the likelihood of a PPMI. We hypothesized that immediate post-PCI assessment could identify a group of patients at very low risk for PPMI. A consecutive series of 258 PCI patients was stratified into 3 groups based on immediate post-PCI assessment. Group I (PPMI not expected) included those with an acceptable angiographic result of treated vessel (residual stenosis < 50%), TIMI 3 flow and absence of any intraprocedural complications. Group II (PPMI not unexpected) included those with an acceptable angiographic result, TIMI 3 flow but with any/all of the following: saphenous vein graft (SVG) PCI, transient closure of culprit vessel or major sidebranch, intracoronary thrombus, prolonged chest pain, electrocardiographic (ECG) changes, hypotension, resolved slow flow/no reflow, bailout glycoprotein IIb/IIIa inhibitor use, loss of a minor sidebranch or any angiographic residual stenosis > 50% with TIMI 3 flow. Group III (PPMI expected) included those with any angiographic result of native coronary artery or SVG with < TIMI 3 flow, unresolved chest pain, hypotension or ECG changes at the end of the PCI, loss of a major sidebranch or vessel, or persistent no-reflow. Group stratification was analyzed in relation to the incidence of PPMI (CK-MB > 3 times the upper limit of normal; 18 24 hours post-PCI). Rate of PPMI: Group I (1/141; 0.7%), Group II (7/71; 9.9%), Group III (5/11; 45.5%) (p < 0.001). The 3 groups did not differ in age, clinical presentation or stent use (p = NS). Sixty out of 105 patients (57.1%) with unstable angina, seventy-seven out of 146 patients (52.7%) with B2/C lesions, and 105/180 patients (58.3%) with unstable angina or B2/C lesions were stratified to Group I. This study demonstrates that immediate post-PCI evaluation of the clinical/angiographic characteristics can predict the likelihood of PPMI and a group of patients at a very low risk for a PPMI can be identified, in whom implications exist for limited hospitalization and post-procedural antithrombotic therapy.