Social Support, Resilience, and Mental Health Among Three High-Risk Groups in Hong Kong: A Mediation Analysis.

Objectives: To compare the prevalence of anxiety/depression, resilience, and social support among nurses, foreign domestic helpers (FDHs), and residents living in subdivided units (SDUs), and to examine their associations in these high-risk groups in Hong Kong during Omicron waves. Methods: We recruited 1,014 nurses, 621 FDHs, and 651 SDU residents from December 2021 to May 2022 in this cross-sectional survey. The depression, anxiety, social support, and resilience levels were measured by the validated scales. The multivariate binary logistic regression and causal mediation analysis were applied to examine the associations. Results: We observed a prevalence of 17.7% in anxiety and 21.6% in depression which were the highest in SDU residents, followed by FDHs, and lowest in nurses. Social support was associated with increased resilience levels and decreased risks of anxiety/depression. The association of social support with mental disorders was partly mediated by resilience, accounting for 30.9% and 20.9% of the total effect of social support on anxiety and depression, respectively. Conclusion: Public health strategies should target improving social support and providing resilience-promoting interventions to help reduce mental disorders in vulnerable groups.

Aveir VR real-world performance and chronic pacing threshold prediction using mapping and fixation electrical data.

AIMS: Aveir VR performance and predictors for its pacing threshold (PCT) in a real-world cohort were investigated. METHODS: Electrical measurements at various stages of an Aveir VR implant were prospectively collected. Predictors for 3-month PCT were studied. A retrospective cohort of consecutive 139 Micra implants was used to compare the PCT evolution. High PCT was defined as ≥1.5 V, using a pulse width of 0.4 ms for Aveir and 0.24 ms for Micra. Excellent PCT was defined as ≤0.5 V at the respective pulse width. RESULTS: Among the 123 consecutive Aveir VR implant attempts, 122 (99.2%) were successful. The majority were of advanced age (mean 79.7) and small body size (mean BSA 1.60). Two patients (1.6%) experienced complications, including one pericardial effusion after device reposition and one intraoperative device dislodgement. Eighty-eight patients reached a 3-month follow-up. Aveir 3-month PCT was correlated with impedance at mapping (P = 0.015), tether mode (P < 0.001), end-of-procedure (P < 0.001), and mapping PCT (P = 0.035), but not with PCTs after fixation (P > 0.05). Tether mode impedance >470 ohms had 88% sensitivity and 71% specificity in predicting excellent 3-month PCT. Although it is more common for Aveir to have high PCT at end of procedure (11.5% for Aveir and 2.2% for Micra, P = 0.004), the rate at 3 months was similar (2.3% for Aveir and 3.1% for Micra, P = 1.000). CONCLUSION: Aveir VR demonstrated satisfactory performance in this high-risk cohort. Pacing thresholds tend to improve to a greater extent than Micra after implantation. The PCT after fixation, even after a waiting period, has limited predictive value for the chronic threshold. Low-mapping PCT and high intraoperative impedance predict chronic low PCT.

Desistance from physical abuse in a national study of Nepal: Protective informal social control and self-compassion.

BACKGROUND: Research on the conditions under which perpetrators desist from child maltreatment has seen greater attention as part of the efforts to break the cycle of maltreatment. New theoretical insights suggest that informal actions (herein protective informal social control of child maltreatment) by network members which communicate warmth, empathy with victim distress, and promote the modeling of positive parenting practices are more likely to increase maltreatment desistance. Likewise, parents' desistance from maltreatment is theorized to impact on adolescents' (victim) cognition and self-compassion. OBJECTIVE: This study examined the relationship among protective informal social control of child maltreatment (protective ISC_CM) by social networks, physical abuse desistance, and adolescent self-compassion. PARTICIPANTS AND SETTING: A nationally representative sample of 1100 mothers and their adolescent children (aged 11-15) in Nepal was obtained. METHODS: Questionnaires were administered to mothers and their adolescent children independently. Hypotheses were tested using regression models with standard errors corrected for clustering within wards. RESULTS: More than 1 in 7 mothers reported perpetrating physical abuse in the past year, and 1 in every 5 adolescents reported being victims of physical abuse. Odds of abuse desistance increase by roughly 10 % for each act of protective ISC_CM reported by the mother. Also, odds of abuse desistance associated with higher adolescent self-compassion, and acts of protective ISC_CM associated with higher levels of adolescent self-compassion. CONCLUSION: The findings suggest that interventions to boost desistance from maltreatment and break the cycle of abuse in Nepal, should focus on promoting protective informal social control actions.

Automatic algorithmic driven monitoring of atrioventricular nodal re-entrant tachycardia ablation to improve procedural safety.

Background: During slow pathway modification for atrioventricular nodal reentrant tachycardia, heart block may occur if ablation cannot be stopped in time in response to high risk electrogram features (HREF). Objectives: To develop an automatic algorithm to monitor HREF and terminate ablation earlier than human reaction. Methods: Digital electrogram data from 332 ablation runs from February 2020 to June 2022 were included. They were divided into training and validation sets which contained 126 and 206 ablation runs respectively. HREF in training set was measured. Then a program was developed with cutoff values decided from training set to capture all these HREF. Simulation ablation videos were rendered using validation set electrogram data. The videos were played to three independent electrophysiologists who each determined when to stop ablation. Timing of ablation termination, sensitivity, and specificity were compared between human and program. Results: Reasons for ablation termination in the training set include short AA time, short VV time, AV block and VA block. Cutoffs for the program were set to maximize program sensitivity. Sensitivity and specificity for the program in the validation set were 95.2% and 91.1% respectively, which were comparable to that of human performance at 93.5% and 95.4%. If HREF were recognized by both human and program, ablations were terminated earlier by the program 90.2% of times, by a median of 574 ms (interquartile range 412-807 ms, p < 0.001). Conclusion: Algorithmic-driven monitoring of slow pathway modification can supplement human judgement to improve ablation safety.

Phospholipid lateral diffusion in the presence of cationic peptides as measured via 31P CODEX NMR.

The effects of two cationic peptides on phospholipid lateral diffusion in binary mixtures of POPC with various anionic phospholipids were measured via 31P CODEX NMR. Large unilamellar vesicles composed of POPC/POPG (70/30 mol/mol), or POPC/DOPS (70/30 mol/mol), or POPC/TOCL (85/15 mol/mol), or POPC/DOPA (50/50 mol/mol) were exposed to either polylysine (pLYS, N = 134 monomers) or KL-14 (KKLL KKAKK LLKKL), a model amphipathic helical peptide, in an amount corresponding to 80% neutralization of the anionic phospholipid charge by the cationic lysine residues. In the absence of added peptide, phospholipid lateral diffusion coefficients (all measured at 10 °C) increased with increasing reduced temperature (T-Tm). The POPC/DOPA mixture was an exception to this generalization, in that lateral diffusion for both components was far slower than any other mixture investigated, an effect attributed to intermolecular hydrogen bonding. The addition of pLYS or KL-14 decreased lateral diffusion in the POPC/DOPS LUV, but had minimal effects in the POPC/POPG LUV, indicating that ease of access of the cationic peptide residues to the anionic phospholipid groups was important. Both cationic peptides produced the opposite effect in the POPC/DOPA case, in that lateral diffusion increased significantly in their presence, with KL-14 being most effective. This latter observation was interpreted in terms of the electrostatic / H-bond model proposed by Kooijman et al. [Journal of Biological Chemistry, 282:11356-11,364, 2007] to describe the mechanism of interaction between the phosphomonoester head group of PA and the tertiary amine of lysine.

Experience of a demand-side subsidy scheme for residential long-term care: perspectives of elderly and their carers.

BACKGROUND: Vouchers, which are demand-side subsidies to targeted groups, are a type of consumer-led near-cash social transfer for specified benefits that have been used in education, health and other sectors. To provide better access to residential care services and an additional choice for elderly people in need, a novel means-tested residential care service voucher has been introduced in Hong Kong for elderly people to purchase places in the private sector to enable consumer-directed care. The objectives of this paper are to analyze the perspectives of voucher users and their carers toward the voucher scheme and to identify key elements in the design that will contribute to meeting the scheme's objectives. METHODS: An exploratory sequential mixed method design was adopted with initial explorative qualitative data collection of the perspectives of elderly people and their carers (Phase 1), which informed the design of the subsequent questionnaire survey (Phase 2). Thirty carers in 5 focus groups and 20 individual interviews with elderly people were conducted between April and May 2018. A total of 401 respondents (373 carers and 28 elderly people) completed the survey questionnaire. Findings from both phases were integrated both narratively and via a joint display. RESULTS: Five key themes summarized the features in two main elements of the design and implementation of the voucher scheme: awareness, meaning that inadequate knowledge and understanding of voucher schemes hinder participation; service needs and types, indicating that the urgent need for residential care services is the key reason for participation; shared responsibility, meaning that a high copayment level discourages participation; choice and flexibility, reflecting appreciation of the additional choices provided by voucher schemes although the availability of residential care beds limits choices; and service quality, indicating mixed perceptions of service quality and the impact of the voucher scheme. Voucher users believe that the voucher scheme is more helpful for relieving the financial burden (98.7%), reducing carers' stress (97.0%) and reducing the waiting time for subsidized homes for elderly people (89.0%) than for increasing choice and flexibility (78.1%) and improving service quality (62.1%). CONCLUSIONS: This study demonstrates how the design of a voucher scheme affects its take-up by targeted beneficiaries. When a voucher scheme is implemented in a long-term care system, it must consider the congruence with existing policies in long-term care provision and financing. The voucher scheme in Hong Kong has been able to generate the utilization of nonsubsidized places in homes for elderly people that were underutilized, but its effectiveness is limited by inadequate knowledge and understanding of the voucher scheme and the availability of residential care places. Giving the purchasing power and choice of providers to beneficiaries has the potential to enhance the quality of services, which will contribute to meeting the objectives. The study findings carry significant implications for long-term care policies and provide insights into the key features of the voucher scheme for residential care services and how to best design and implement a voucher scheme for elderly people in the context of policy objectives and a long-term care policy.

Building Awareness of Diagnosis Together: Ambiguity During Progression-Free Survival Experienced by Patients With Lung Cancer and Caregivers in China.

BACKGROUND: Lung cancer, as a multistep and multifactorial disease, is among the most fatal cancers worldwide. As new therapies are developed and early screening increases, patients tend to experience progression-free survival (PFS) as a coexistence of living and dying simultaneously. OBJECTIVE: The aim of this study was to explore the awareness context experienced by Chinese elderly patients and family members. METHODS: Interviews were conducted with 20 interviewees, including 13 elderly patients with lung cancer and 7 caregivers that were recruited using purposive sampling. Semistructured, face-to-face, in-depth interviews were conducted using a qualitative descriptive approach. RESULTS: Ambiguity was commonly experienced by patients with lung cancer with PFS. Three themes emerged from the data analysis: "ambiguity in cancer diagnosis," "ambiguity in prognostic awareness," and "ambiguity in identity." In this case, ambiguity refers to a situation or context in which patients are uncertain about whether there will be a recurrence of their cancer and when it might occur. CONCLUSIONS: The findings highlighted that patients experienced ambiguity in response to unclear diagnoses, uncertain prognoses, and identity crises during PFS. IMPLICATIONS FOR PRACTICE: Healthcare teams should be equipped with psychosocial knowledge and communication skills to manage ambiguity in diagnosis and prognosis for patients with PFS.

What determines Hong Kong South Asians' perceptions on COVID-19 vaccine? Implications on culturally appropriate vaccine messages for ethnic minority community.

Guided by the behavioral model of health service use, this study examined the effect of South Asians' perceptions of healthcare, religious belief, and socioeconomic status on their perceived benefits and risks of COVID-19 vaccines (N = 245). Cross-sectional survey was used. Logistic regressions results showed that higher levels of perceived involvement in South Asian community health and trust in the healthcare system were associated with higher odds of reporting perceived vaccine benefits. Permanent residents, students (vs. unemployed), and Pakistani (vs. Indians) also perceived the vaccine as beneficial. On the other hand, believing that the body was sacred and being Buddhist (vs. Hindu) were associated with higher odds of perceiving severe vaccination risk. Those who believed that God would cure COVID-19 and those with higher education tended to perceive the vaccine as having a limited effect. Implications on designing culturally appropriate COVID-19 vaccines messages in interethnic settings are discussed.

Effects of students' perception of teachers' ethnic-racial socialization on students' ethnic identity and mental health in rural China's schools.

Introduction: Using students in the Liangshan Yi autonomous prefectures of southwestern China (n = 585; 13-15 years old), we examined (i) the effects of students' perception of their teachers' ethnic-racial socialization on their ethnic identity and mental health outcomes of depressive and stress symptoms; (ii) the effects of students' ethnic identity on their depressive and stress symptoms; (iii) the differential associations among these factors in Yi ethnic minority versus Han cultural majority students. Methods: We conducted a cross-sectional survey and used multistage sampling to collect the information. Chinese-validated standardized measures were used: the Patient Health Questionaires-9, Children's Revised Impact of Event Scale-8, Multigroup Ethnic Identity Measure, Cultural Socialization Scale, and Teachers' Attitude on Adoption of Cultural Diversity Scale. Multigroup confirmatory factor analysis and multigroup structural equation modeling were employed. Results: Comparing the findings in Yi and Han students, their perception of teachers' ethnic-racial socialization had dissimilar effects on their ethnic identity and mental health outcomes. Three key findings comparing the differences between Yi and Han students were as follows: (i) students' perception of their teachers' multicultural socialization practices positively affected the ethnic identity of both Yi and Han young people; however, their perception of their teachers' socializing them to their own cultures did not exert any effect; (ii) students' perception of teachers' multicultural socialization practices had different mental health effects on Yi versus Han students; and (iii) ethnic identity affected the mental health of Yi ethnic minority students only. Conclusion: The findings underscore the importance of teachers' multicultural socialization in the ethnic identity development of both Yi ethnic minority and Han majority students. Ethnic identity serves as a linking variable bridging perceived teachers' multicultural socialization practices and mental health in Yi ethnic minority students but not among the Han cultural majority youths. Research, practice, and policy implications relevant to the global context are also discussed.

Vulnerable populations during COVID-19 response: Health-related quality of life among Chinese population and its influence due to socio-demographic factors and loneliness.

Background: Infection control policy affected people's wellbeing during the COVID-19 pandemic, especially those vulnerable populations. This study aimed to compare the health-related quality of life (HRQoL) of the Hong Kong (HK) Chinese population under the pandemic with the normative profiles and explore its influencing factors, including socio-demographic characteristics, loneliness, and the interaction between them. Methods: A cross-sectional questionnaire survey (301 online and 202 in-person) was conducted between June and December 2020 among the adult Chinese population during the 2nd wave of COVID-19 in HK. HRQoL was measured by a Hong Kong validated EQ-5D-5L instrument (EQ-5D-5L HK). Loneliness was measured by a single-item question regarding the frequency of the participants reporting feeling lonely and their subjective social status was measured by the MacArthur Scale of Subjective Social Status. A series of Tobit regressions was conducted. The interaction terms between socio-demographics and loneliness were also examined to decide their association with HRQoL. Results: A total of 503 responses were collected. The level of HRQoL of the respondents was significantly lower than the referred norms profile among the local general population. The findings identified that younger age, single, a higher subjective social status, and a lower level of loneliness were significantly associated with better HRQoL. Moreover, age and marital status were significant moderators in the relationship between loneliness and HRQoL. Conclusion: The present study found that some population groups face additional vulnerabilities during the pandemic in terms of declined HRQoL. In addition, reducing loneliness can protect the HRQoL during the pandemic, especially among older people. This article provides useful information for policy-makers to design and promote effective services or provide education to improve the connection of people and recover from the global pandemic.

Preference of caregivers on residential care homes for older persons with versus without communication problems: a discrete choice experiment.

BACKGROUND: A residential care service voucher scheme has been introduced to expand the capacity and enhance choice of public-funded long-term care (LTC) in Hong Kong, enabling users to have greater choices over the types of LTC facilities. Older persons with communication problems have difficulties in understanding the care options available to them and expressing their preferences to care homes and daily service delivery, therefore hindering their ability to exercise control and choice. Thus, they may have different needs and preferences for the facilities than others due to their conditions. This study therefore aimed to investigate their preference for care homes in comparison with those without communication problems. METHODS: A discrete choice experiment was conducted to elicit preference for six attributes derived from prior studies. The family caregivers of a random sample of older voucher holders were invited to undertake face-to-face interview. Willingness-to-pay (WTP) for the attributes was estimated for those with or without communication problems separately. RESULTS: Two hundred eighty-three caregivers provided valid responses (74% response rate). Caregivers of those with communication problem preferred facilities operated by non-governmental organizations (WTP=HK$1777.4) and shorter travelling time (WTP=HK$1502.5 for <=0.5 hours), while those without the problem had greater preference for fewer roommates (WTP=HK$3048.1 for single room) and extra healthcare professionals (WTP=HK$1765.5). Heterogenous WTPs were identified from those with different income, marital status and caregivers' age. CONCLUSIONS: The reputation, greater space and staff, and proximity/familiarity of the facilities were important for those with communication problems. To help meet these preferences, the facilities could establish collaborations with local community-based service providers and build their own outreach team to familiarize themselves with older persons. Additionally, household income and informal support availability should be considered for care planning.

Healthcare vouchers for better elderly services? Input from private healthcare service providers in Hong Kong.

Hong Kong's health system comprises parallel and segmented public and private financed and provided sectors, in which access to the limited public primary healthcare has been an issue. This gave the government the impetus to implement the Elderly Healthcare Voucher Scheme since 2009, providing Hong Kong resident aged 65 and above an annual entitlement of HK$2,000 to purchase private primary healthcare. This was to reduce the demand for public healthcare and encourage the use of private preventive care and chronic disease management. To evaluate the effectiveness and impact of the voucher scheme, in-depth understanding from the providers' perspectives on implementation barriers and facilitators was studied. The perspectives of 33 service providers were sought through five focus group discussions and seven telephone interviews between 2016 and 2017. Mixed sampling strategies were used, and the discussion covered three main areas: (a) factors that affect the impact of voucher scheme in bridging the private and public primary healthcare sector; (b) perceived barriers to participation in the voucher scheme and (c) potential enhancement of the voucher scheme. Participants agreed that the voucher scheme encouraged uptake of private primary care for acute episodes, but not for chronic disease management and rehabilitation due to inadequate financial entitlements and the elderly persons' lack of knowledge on the services covered. Low financial incentives, tedious administrative work and inadequate communications were identified as barriers for enrolment. The voucher scheme has resulted in increased utilisation of private primary healthcare but has not reduced the demand for public primary healthcare. Fundamental questions remain about the scheme's potential role in improving universal health coverage and financial sustainability which are related to the program design and to whether this is the better mechanism, or a complementary mechanism to address some of the more complex health system priorities including better chronic disease management.

Neighborhood as a place to foster generalized trust among young adults in Hong Kong.

AIMS: Generalized trust is a crucial determinant of individual and social well-being and is the fundamental element of a healthy society. However, a decline in generalized trust was observed among Hong Kong young adults, despite local neighborhoods, and placed-based experiences gaining popularity among Hong Kong young people. Hence, this paper examines the effect of neighborhood-level factors on promoting generalized trust. METHOD: Cross-sectional data were obtained from 1635 young adults aged 17-23 through mixed-mode surveys-a computer-assisted telephone interviewing CATI telephone survey, an online survey, and a mail survey. RESULTS: Logistic regression results showed that neighborhood cohesiveness, being an active member of a religious organization, being an active member of a local youth organization, acceptance of ethnic diversity, and having a good parental relationship were related to higher odds of reporting generalized trust. CONCLUSION: Research and practice implications and the international relevance of the findings are discussed.

Multilevel Determinants of COVID-19 Vaccine Uptake Among South Asian Ethnic Minorities in Hong Kong: Cross-sectional Web-Based Survey.

BACKGROUND: The COVID-19 pandemic continues to have a disproportionate effect on ethnic minorities. Across countries, greater vaccine hesitancy has been observed among ethnic minorities. After excluding foreign domestic helpers, South Asians make up the largest proportion of ethnic minorities in Hong Kong. It is necessary to plan for COVID-19 vaccination promotional strategies that cater to the unique needs of South Asians in Hong Kong. OBJECTIVE: This study investigated the prevalence of COVID-19 vaccine uptake among a sample of South Asians in Hong Kong. We examined the effects of sociodemographic data and factors at individual level (perceptions), interpersonal level (information exposure on social media), and sociostructural level (cultural) based on the socioecological model. METHODS: A cross-sectional web-based survey was conducted on May 1-31, 2021. Participants were South Asian people aged 18 years or older living in Hong Kong; able to comprehend English, Hindi, Nepali, or Urdu; and having access to a smartphone. Three community-based organizations providing services to South Asians in Hong Kong facilitated the data collection. The staff of the community-based organizations posted the study information in WhatsApp groups involving South Asian clients and invited them to participate in a web-based survey. Logistic regression models were fit for data analysis. RESULTS: Among 245 participants, 81 (33.1%) had taken at least one dose of the COVID-19 vaccine (one dose, 62/245, 25.2%; and both doses, 19/245, 7.9%). After adjusting for significant background characteristics, cultural and religious reasons for COVID-19 vaccine hesitancy were associated with lower COVID-19 vaccine uptake (adjusted odds ratio [AOR] 0.83, 95% CI 0.71-0.97; P=.02). At the individual level, having more positive attitudes toward COVID-19 vaccination (AOR 1.31, 95% CI 1.10-1.55; P=.002), perceived support from significant others (AOR 1.29, 95% CI 1.03-1.60; P=.03), and perceived higher behavioral control to receive COVID-19 vaccination (AOR 2.63, 95% CI 1.65-4.19; P<.001) were associated with higher COVID-19 vaccine uptake, while a negative association was found between negative attitudes and the dependent variable (AOR 0.73, 95% CI 0.62-0.85; P<.001). Knowing more peers who had taken the COVID-19 vaccine was also associated with higher uptake (AOR 1.39, 95% CI 1.11-1.74; P=.01). At the interpersonal level, higher exposure to information about deaths and other serious conditions caused by COVID-19 vaccination was associated with lower uptake (AOR 0.54, 95% CI 0.33-0.86; P=.01). CONCLUSIONS: In this study, one-third (81/245) of our participants received at least one dose of the COVID-19 vaccine. Cultural or religious reasons, perceptions, information exposure on social media, and influence of peers were found to be the determinants of COVID-19 vaccine uptake among South Asians. Future programs should engage community groups, champions, and faith leaders, and develop culturally competent interventions.

Vouchers for primary healthcare services in an ageing world? The perspectives of elderly voucher recipients in Hong Kong.

Considering the ageing population in economically advanced regions across the world, measures are necessary to enhance the health of the older population as well as contain public healthcare spending. Hong Kong implements the Elderly Health Care Voucher Scheme (EHCVS), providing older people aged 65 or above an annual subsidy of visiting private healthcare service providers for chronic disease prevention and management. The services also aim at reallocating demand from the public to private sector as well as improve quality of services. This qualitative study explored the experiences of EHCVS recipients (n = 55, aged 61-94) with eight focus group interviews in Hong Kong in the year 2016. Convenience sampling was used. Research questions were: (1) Why do older people choose not to use EHCVS for preventive as well as disease management services among older people in Hong Kong? (2) What are the barriers to reallocating demand from the public to private sector? (3) In what ways did EHCVS improve the quality of primary care services for older people? Using a deductive and inductive approach, eight qualitative themes were identified. Findings suggested that the non-targeted services and inadequate knowledge on EHCVS deterred older people from using the vouchers for disease management and prevention. The relatively expensive private services, lack of trust in the private sector, low public clinic fees and good services quality of the public sector, together with inadequate private practitioners in the healthcare market were barriers that hinder demand reallocation. Nevertheless, the quality of primary care services had been improved after the implementation of EHCVS with shortened wait times and opportunities to discuss health-related issues with private practitioners. Findings were discussed with practice, policy and research implications.

ProxyPhos sensors for the detection of negatively charged membranes.

Membrane-embedded negatively charged phospholipids (MENCP) can be used as biomarkers for a range of biological processes, including early detection of apoptosis in animal cells, drug-induced phospholipidosis, and selective detection of bacterial over animal cells. Currently, several technologies for the detection of apoptosis and bacterial cells are based on the recognition of MENCPs, including the AnnexinV stain and PSVue™ probes. As probes, these technologies have limitations, the most significant of which is the need for washing the unbound probe away to achieve optimal signal. In contrast, a turn-on chemosensor selective for MENCP would address this shortcoming, and allow for a more rapid protocol for the detection of apoptosis, bacteria and for other relevant applications. In this work, the aim was to explore whether ProxyPhos chemosensors, previously reported by our group for the detection of proximally phosphorylated peptides and proteins, could be re-purposed for the detection of MENCPs. Six lead ProxyPhos sensors were screened against synthetic vesicles containing biologically relevant negatively charged phospholipids including phosphatidic acid (PA), phosphatidylglycerol (PG), cardiolipin (CL) and phosphatidylserine (PS). Through these screens, ProxyPhos sensors exhibiting high selectivity for the detection of MENCPs over zwitterionic lipids were identified. Particular selectivity was observed for PA and CL. Sensitivity of the lead sensors for MENCPs was suitable for the detection of apoptosis: ProxyPhos detected vesicles containing as little as 2.5% PS and detected camptothecin-induced apoptosis in mammalian cells in flow cytometry experiments. The results suggest that ProxyPhos sensors can be used for the detection of MENCPs in synthetic vesicles and live mammalian cells.

A Molecular Rotor Possessing an H-M-H "Spoke" on a P-M-P "Axle": A Platinum(II) trans-Dihydride Spins Rapidly Even at 75 K.

A new class of low-barrier molecular rotors, metal trans-dihydrides, is suggested here. To test whether rapid rotation can be achieved, the known complex trans-H2Pt(P(t)Bu3)2 was experimentally studied by (2)H and (195)Pt solid-state NMR spectroscopy (powder pattern changes with temperature) and computationally modeled as a (t)Bu3P-Pt-P(t)Bu3 stator with a spinning H-Pt-H rotator. Whereas the related chloro-hydride complex, trans-H(Cl)Pt(P(t)Bu3)2, does not show rotational behavior at room temperature, the dihydride trans-H2Pt(P(t)Bu3)2 rotates fast on the NMR time scale, even at low temperatures down to at least 75 K. The highest barrier to rotation is estimated to be ∼3 kcal mol(-1), for the roughly 3 Šlong rotator in trans-H2Pt(P(t)Bu3)2.

Centerband-only-detection-of-exchange (31)P nuclear magnetic resonance and phospholipid lateral diffusion: theory, simulation and experiment.

Centerband-only-detection-of-exchange (CODEX) (31)P NMR lateral diffusion measurements were performed on dimyristoylphosphatidylcholine (DMPC) assembled into large unilamellar spherical vesicles. Optimization of sample and NMR acquisition conditions provided significant sensitivity enhancements relative to an earlier first report (Q. Saleem, A. Lai, H. Morales, and P. M. Macdonald, Chem. Phys. Lipids, 2012, 165, 721). An analytical description was developed that permitted the extraction of lateral diffusion coefficients from CODEX data, based on a Gaussian-diffusion-on-a-sphere model (A. Ghosh, J. Samuel, and S. Sinha, Europhys. Lett., 2012, 98, 30003-p1) as relevant to CODEX (31)P NMR measurements on a population of spherical unilamellar phospholipid bilayer vesicles displaying a distribution of vesicle radii.

NMR methods for measuring lateral diffusion in membranes.

Lateral diffusion is a fundamental property of biological membrane components, important for a host of biomembrane functions. Although long studied, novel aspects of the relationship between the structure of membrane components and their lateral diffusion properties continue to emerge. NMR-based lateral diffusion measurements are complicated by the spectral broadening arising from the slow anisotropic motions in membranes. Nevertheless, both pulsed field gradient (PFG) and exchange spectroscopy (EXSY) methods can be adapted to permit NMR measurements of lateral diffusion in membranes. These variously will be described in overview, highlighting advantages and limitations of each, but with particular emphasis on results from our laboratory using (1)H PFG NMR measurements in magnetically aligned bicelles and (31)P CODEX (Centreband-Only-Detection-of-Exchange) measurements in spherical phospholipid vesicles.

Lateral diffusion of bilayer lipids measured via (31)P CODEX NMR.

We have employed (31)P CODEX (centre-band-only-detection-of-exchange) NMR to measure lateral diffusion coefficients of phospholipids in unilamellar lipid bilayer vesicles consisting of 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC), alone or in mixtures with 30 mol% 1-palmitoyl-2-oleoyl-phosphatidylglycerol (POPG) or cholesterol (CHOL). The lateral diffusion coefficients of POPC and POPG were extracted from experimental CODEX signal decays as a function of increasing mixing time, after accounting for the vesicle's size and size distribution, as determined via dynamic light scattering, and the viscosity of the vesicular suspension, as determined via (1)H pulsed field gradient NMR. Lateral diffusion coefficients for POPC and POPG determined in this fashion fell in the range 1.0-3.2 × 10(-12) m(2) s(-1) at 10 °C, depending on the vesicular composition, in good agreement with accepted values. Thus, two advantages of (31)P CODEX NMR for phospholipid lateral diffusion measurements are demonstrated: no labelling of the molecule of interest is necessary, and multiple lateral diffusion coefficients can be measured simultaneously. It is expected that this approach will prove particularly useful in diagnosing heterogeneities in lateral diffusion behaviours, such as might be expected for specific lipid-lipid or lipid-protein interactions, and thermotropic or electrostatically induced phase inhomogeneities.