Substitution of Coxsackievirus A16 VP1 BC and EF Loop Altered the Protective Immune Responses in Chimera Enterovirus A71

Hand, foot and mouth disease (HFMD) is a childhood disease caused by enterovirus A71 (EV-A71) and coxsackievirus A16 (CV-A16). Capsid loops are important epitopes for EV-A71 and CV-A16. Seven chimeric EV-A71 (ChiE71) involving VP1 BC (45.5% similarity), DE, EF, GH and HI loops, VP2 EF loop and VP3 GH loop (91.3% similarity) were substituted with corresponding CV-A16 loops. Only ChiE71-1-BC, ChiE71-1-EF, ChiE71-1-GH and ChiE71-3-GH were viable. EV-A71 and CV-A16 antiserum neutralized ChiE71-1-BC and ChiE71-1-EF. Mice immunized with inactivated ChiE71 elicited high IgG, IFN-γ, IL-2, IL-4 and IL-10. Neonatal mice receiving passive transfer of WT EV-A71, ChiE71-1-EF and ChiE71-1-BC immune sera had 100%, 80.0% and no survival, respectively, against lethal challenges with EV-A71, suggesting that the substituted CV-A16 loops disrupted EV-A71 immunogenicity. Passive transfer of CV-A16, ChiE71-1-EF and ChiE71-1-BC immune sera provided 40.0%, 20.0% and 42.9% survival, respectively, against CV-A16. One-day-old neonatal mice immunized with WT EV-A71, ChiE71-1-BC, ChiE71-1-EF and CV-A16 achieved 62.5%, 60.0%, 57.1%, and no survival, respectively, after the EV-A71 challenge. Active immunization using CV-A16 provided full protection while WT EV-A71, ChiE71-1-BC and ChiE71-1-EF immunization showed partial cross-protection in CV-A16 lethal challenge with survival rates of 50.0%, 20.0% and 40%, respectively. Disruption of a capsid loop could affect virus immunogenicity, and future vaccine design should include conservation of the enterovirus capsid loops.

[Analysis of the impact of health management measures for entry personnel on imported Dengue fever in Guangdong Province, 2020-2022]

Objective: To explore the impact of health management measures for entry personnel (entry management measures) against COVID-19 on the epidemiological characteristics of imported Dengue fever in Guangdong Province from 2020 to 2022. Methods: Data of imported Dengue fever from January 1, 2016 to August 31, 2022, mosquito density surveillance from 2016 to 2021, and international airline passengers and Dengue fever annual reported cases from 2011 to 2021 in Guangdong were collected. Comparative analysis was conducted to explore changes in the epidemic characteristics of imported Dengue fever before the implementation of entry management measures (from January 1, 2016 to March 20, 2020) and after the implementation (from March 21, 2020 to August 31, 2022). Results: From March 21, 2020, to August 31, 2022, a total of 52 cases of imported Dengue fever cases were reported, with an imported risk intensity of 0.12, which were lower than those before implementation of entry management measures (1 828, 5.29). No significant differences were found in the characteristics of imported cases before and after implementation of entry management measures, including seasonality, sex, age, career, and imported countries (all P>0.05). 59.62% (31/52) of cases were found at the centralized isolation sites and 38.46% (20/52) at the entry ports. However, before implementation of entry management measures, 95.08% (1 738/1 828) of cases were found in hospitals. Among 51 cases who had provided entry dates, 82.35% (42/51) and 98.04% (50/51) of cases were found within seven days and fourteen days after entry, slightly higher than before implementation [(72.69%(362/498) and 97.59% (486/498)]. There was significant difference between the monthly mean values of Aedes mosquito larval density (Bretto index) from 2020 to 2021 and those from 2016 to 2019 (Z=2.83, P=0.005). There is a strong positive correlation between the annual international airline passengers volume in Guangdong from 2011 to 2021 and the annual imported Dengue fever cases (r=0.94, P<0.001), and a positive correlation also existed between the international passenger volume and the annual indigenous Dengue fever cases (r=0.72, P=0.013). Conclusions: In Guangdong, the entry management measures of centralized isolation for fourteen days after entry from abroad had been implemented, and most imported Dengue fever cases were found within fourteen days after entry. The risk of local transmission caused by imported cases has reduced significantly.

[Impact of capsular tension ring implantation in cataract patients with high myopia]

The capsular tension ring (CTR) can stabilize the capsule, support the lax zonules, and inhibit the proliferation and migration of lens epithelial cells. Clinically, CTR is mostly used in patients with zonular weakness, which can improve the stability of intraocular lens (IOL) and reduce the incidence of posterior capsular opacity (PCO). The relatively large capsular bag volume, zonular weakness in cataract patients with high myopia may increase the instability of IOL and PCO. Therefore, many clinicians have implanted CTR in cataract patients with high myopia. In this review, we summarized the application of CTR in cataract patients with high myopia.

[Occurrence of live-born twins with birth weight-discordance and its relationship to the adverse birth outcomes]

Objective: To investigate the occurrence of live-born twins with birth weight-discordance and its relationship to adverse birth outcomes. Methods: A retrospective analysis was performed on 4 011 pairs of live-born twins in the Third Affiliated Hospital of Guangzhou Medical University from January 2011 to December 2020. Based on the birth-weight discordance (∆BW, ∆BW=(birth-weight_big-birth-weight_small)/birth-weight_big×100%)), twins were divided into 4 groups, including ∆BW≤15%,>15%-20%,>20%-25%, and>25%. The differences in maternal and neonatal outcomes among 4 groups were explored. Then the correlation between ∆BW and neonatal adverse outcomes were explored. Results: The ΔBW was 9 (4, 16)% and males were accounted for 53.8% (4 315 cases) of 4 011 pairs of twins. The gestational age was (35.3±2.7) weeks at birth. There were 2 908 pairs (72.5%) of twins with ΔBW≤15%, 481 pairs (12.0%) with ΔBW>15%-20%, 281 pairs (7.0%) with ΔBW 20%-≤25%, and 341 twin pairs (8.5%) with ΔBW>25%. With ∆BW of 20% as the diagnostic cutoff, the incidence of birth weight discordance was 15.5% (622/4 011). The proportion of natural births in the ∆BW≤15% group was higher than that in the ∆BW>15%-20% group (10.5% (288/2 740) vs. 6.3% (29/463), P<0.008 3). The ∆BW>25% group had a significantly higher prevalence of maternal hypertensive disorders during pregnancy than that of the other 3 groups (25.5% (87/341) vs. 16.7% (47/281) vs.17.3% (83/480) vs. 13.8% (400/2 899), all P<0.008 3). Univariate analysis found that the ΔBW>25% group had a lower gestational age and a higher rate of preterm birth than the other groups. The rate of extremely low birth weight (ELBW) or very low birth weight (VLBW), small for gestational age (SGA), and transferring to the department of neonatology in the smaller twins were significantly different among the 4 groups (all P<0.05). Multivariate analysis showed that higher degree of birth weight discordance was all positively associated with the rate of ELBW, SGA, and transferring to the department of neonatology in smaller twin, even after adjusting maternal age and gestational hypertension, year of birth, mode of delivery, gender, and gestational age (all P<0.05). Moreover, the Mantel-Haenszel test also indicated that there were significantly low to moderate correlations between ΔBW and the unfavorable outcomes (r=0.22, 0.53, 0.21, all P<0.001, respectively). The receiver operating characteristic (ROC) curve found that adverse birth outcomes would be well predicted by birth weight-discordant when the diagnostic cut-off of ΔBW was 12%-17%, with an acceptable sensitivity (0.53-0.78) and a high specificity (0.72-0.79). Conclusions: Birth weight discordant is not uncommon in live-born twins, and is associated with adverse outcomes including ELBW, SGA, and transferring to the department of neonatology in the small twins. Besides, the risk is linearly related to the increase of ΔBW. In the future, more researches are needed to explore the underline mechanism and long-term impact of birth weight discordance, to guide the prevention and management.

Mentoring in palliative medicine in the time of covid-19: a systematic scoping review : Mentoring programs during COVID-19

INTRODUCTION

The redeployment of mentors and restrictions on in-person face-to-face mentoring meetings during the COVID-19 pandemic has compromised mentoring efforts in Palliative Medicine (PM). Seeking to address these gaps, we evaluate the notion of a combined novice, peer-, near-peer and e-mentoring (CNEP) and interprofessional team-based mentoring (IPT) program.

METHODS

A Systematic Evidence Based Approach (SEBA) guided systematic scoping review was carried out to study accounts of CNEP and IPT from articles published between 1st January 2000 and 28th February 2021. To enhance trustworthiness, concurrent thematic and content analysis of articles identified from structured database search using terms relating to interprofessional, virtual and peer or near-peer mentoring in medical education were employed to bring together the key elements within included articles.

RESULTS

Fifteen thousand one hundred twenty one abstracts were reviewed, 557 full text articles were evaluated, and 92 articles were included. Four themes and categories were identified and combined using the SEBA's Jigsaw and Funnelling Process to reveal 4 domains - characteristics, mentoring stages, assessment methods, and host organizations. These domains suggest that CNEP's structured virtual and near-peer mentoring process complement IPT's accessible and non-hierarchical approach under the oversight of the host organizations to create a robust mentoring program.

CONCLUSION

This systematic scoping review forwards an evidence-based framework to guide a CNEP-IPT program. At the same time, more research into the training and assessment methods of mentors, near peers and mentees, the dynamics of mentoring interactions and the longitudinal support of the mentoring relationships and programs should be carried out.

[Course of disease and related epidemiological parameters of COVID-19: a prospective study based on contact tracing cohort]

Objective: To analyze the course of disease and epidemiological parameters of COVID-19 and provide evidence for making prevention and control strategies. Methods: To display the distribution of course of disease of the infectors who had close contacts with COVID-19 cases from January 1 to March 15, 2020 in Guangdong Provincial, the models of Lognormal, Weibull and gamma distribution were applied. A descriptive analysis was conducted on the basic characteristics and epidemiological parameters of course of disease. Results: In total, 515 of 11 580 close contacts were infected, with an attack rate about 4.4%, including 449 confirmed cases and 66 asymptomatic cases. Lognormal distribution was fitting best for latent period, incubation period, pre-symptomatic infection period of confirmed cases and infection period of asymptomatic cases; Gamma distribution was fitting best for infectious period and clinical symptom period of confirmed cases; Weibull distribution was fitting best for latent period of asymptomatic cases. The latent period, incubation period, pre-symptomatic infection period, infectious period and clinical symptoms period of confirmed cases were 4.50 (95%CI:3.86-5.13) days, 5.12 (95%CI:4.63-5.62) days, 0.87 (95%CI:0.67-1.07) days, 11.89 (95%CI:9.81-13.98) days and 22.00 (95%CI:21.24-22.77) days, respectively. The latent period and infectious period of asymptomatic cases were 8.88 (95%CI:6.89-10.86) days and 6.18 (95%CI:1.89-10.47) days, respectively. Conclusion: The estimated course of COVID-19 and related epidemiological parameters are similar to the existing data.

[Analysis on characteristics and influencing factors of COVID-19 confirmed cases with viral nucleic acid re-positive after discharge in Guangdong Province]

Objective: To analyze the epidemiological characteristics and influencing factors of COVID-19 confirmed cases with viral nucleic acid re-positive in anal and/or throat swabs after discharge during the domestic imported epidemic stage in Guangdong Province in early 2020. Methods: The COVID-19 confirmed cases with the onset time before March 1, 2020 in Guangdong Province were collected to analyze the demographic data, epidemiological characteristics, and specimen collection and testing data after discharge. Logistic regression model was used for influencing factors analysis of re-positive cases. Results: A total of 1 286 COVID-19 confirmed cases were included, the M(Q₁,Q₃) of age was 44(32,58)years, 617 cases were male, 224 cases were re-positive in anal and/or throat swabs with the re-positive rate 17.42%. The M(Q₁,Q₃) of age of re-positive cases was 35(23, 50) years, which was younger than that of re-negative cases age was those 46(33, 59) years (P<0.001). With the increase of age, re-positive rate decreased (χ²_trend=52.73, P<0.001). 85.27% (191/224) of re-positive cases were found in 14 d after discharge, the duration time of re-positive status was 13(7, 24) d, and 81.69% (183/224) of re-positive cases were re-tested negative in 28 d after re-positive date. No fever and other symptoms had been observed among re-positive cases during the whole follow-up. No secondary infectious cases had been found among close contacts after 14 d of centralized isolation and sampling screening. Univariate logistic regression model analysis revealed that the influencing factors of the re-positive cases included age, occupation, clusters, clinical types, and admission time. Multivariate logistic regression model analysis revealed that age was an independent risk factor. Conclusions: SARS-CoV-2 viral nucleic acid re-positive is found in COVID-19 confirmed cases after discharge in Guangdong Province. Most re-positive cases are confirmed among 14 d after discharge and re-test to negative among 28 d after re-positive date. Age is an risk factor for re-positive cases after discharge.

Seroepidemiology of enterovirus D68 infection in Kuala Lumpur, Malaysia between 2013 and 2015

Enterovirus D68 (EV-D68) is an emerging respiratory pathogen since the 2014 outbreak in the United States. A low level of virus circulation has been reported in Kuala Lumpur, Malaysia, in the past. However, the extent of the infection in Malaysia is not known. In the present study, we determine the seroepidemiology of EV-D68 in Kuala Lumpur, Malaysia, before and after the United States outbreak in August 2014. A luciferase-based seroneutralization test was developed using a clone-derived prototype Fermon strain carrying a nanoluciferase marker. We screened the neutralization capacity of 450 serum samples from children and adults (1-89 years old) collected between 2013 and 2015. EV-D68 seropositivity increased with age, with children aged 1-3 showing significantly lower seroprevalence compared to adults. Multivariate analysis showed that older age groups 13-49 years (odds ratio [OR] = 4.78; 95% confidence interval [CI] = 2.69-8.49; p < 0.0001) and ≥50 years (OR = 3.83; 95% CI = 2.19-6.68; p < 0.0001) were more likely to be EV-D68 seropositive than children <13 years. Sampling post-September 2014 compared to pre-Sept 2014 also predicted seropositivity (OR = 1.66; 95% CI = 1.04-2.65). The presence of neutralizing antibodies against EV-D68 in the study population suggests that EV-D68 was circulating before 2014. A higher seropositivity post-September 2014 suggests that Malaysia also experienced an upsurge in EV-D68 infections after the United States outbreaks in August 2014. A low seropositivity rate observed in children, especially those aged 1-3 years old, suggests that they are at risk and should be prioritized for future vaccination.

Teaching and assessing communication skills in the postgraduate medical setting: a systematic scoping review

BACKGROUND

Poor communication skills can potentially compromise patient care. However, as communication skills training (CST) programs are not seen as a priority to many clinical departments, there is a discernible absence of a standardised, recommended framework for these programs to be built upon. This systematic scoping review (SSR) aims to gather prevailing data on existing CSTs to identify key factors in teaching and assessing communication skills in the postgraduate medical setting.

METHODS

Independent searches across seven bibliographic databases (PubMed, PsycINFO, EMBASE, ERIC, CINAHL, Scopus and Google Scholar) were carried out. Krishna's Systematic Evidence-Based Approach (SEBA) was used to guide concurrent thematic and content analysis of the data. The themes and categories identified were compared and combined where possible in keeping with this approach and then compared with the tabulated summaries of the included articles.

RESULTS

Twenty-five thousand eight hundred ninety-four abstracts were identified, and 151 articles were included and analysed. The Split Approach revealed similar categories and themes: curriculum design, teaching methods, curriculum content, assessment methods, integration into curriculum, and facilitators and barriers to CST. Amidst a wide variety of curricula designs, efforts to develop the requisite knowledge, skills and attitudes set out by the ACGME current teaching and assessment methods in CST maybe categorised into didactic and interactive methods and assessed along Kirkpatrick's Four Levels of Learning Evaluation.

CONCLUSIONS

A major flaw in existing CSTs is a lack of curriculum structure, focus and standardisation. Based upon the findings and current design principles identified in this SSR in SEBA, we forward a stepwise approach to designing CST programs. These involve 1) defining goals and learning objectives, 2) identifying target population and ideal characteristics, 3) determining curriculum structure, 4) ensuring adequate resources and mitigating barriers, 5) determining curriculum content, and 6) assessing learners and adopting quality improvement processes.

Parental bereavement - impact of death of neonates and children under 12 years on personhood of parents: a systematic scoping review

BACKGROUND

Losing a child tragically impacts the well-being and functioning of parents. With these effects extending beyond emotional, physical morbidity and compromising self-perceptions, appropriate, longitudinal, timely and personalised support is key to effective care of bereaved parents. However, in the absence of a comprehensive understanding of parental bereavement, effective support of bereaved parents remains suboptimal. To address this gap, we scrutinise prevailing data on the effects of a child's death, aged 0-12 years, through the lens of the Ring Theory of Personhood (RToP).

METHODS

To study prevailing accounts of bereaved parents following the death of a child, we adopt Krishna's Systematic Evidence Based Approach (SEBA) to structure our Systematic Scoping Review (SSR in SEBA).

RESULTS

Three thousand seventy-four abstracts were reviewed, 160 full text articles were evaluated, and 111 articles were included and analysed using thematic and content analysis. Four themes/categories were identified relating to the four rings of the RToP. Findings reveal that static concepts of protective and risk factors for grief are misplaced and that the support of healthcare professionals is key to assisting bereaved parents.

CONCLUSION

In the absence of consistent support of bereaved parents, this study highlights the need for effective training of healthcare professionals, beginning with an appreciation that every aspect of an individual parent's personhood is impacted by the loss of their child. Acknowledging grief as a complex, evolving and personalised process subjected to parental characteristics, settings, context and available support, this SSR in SEBA calls attention to effective nurturing of the relationship between parents and healthcare professionals, and suggests use of the RToP to assess and direct personalised, timely, specific support of parents in evolving conditions. We believe the findings of this review also call for further studies to support healthcare professionals as they journey with bereaved parents.

Postgraduate ethics training programs: a systematic scoping review

BACKGROUND

Molding competent clinicians capable of applying ethics principles in their practice is a challenging task, compounded by wide variations in the teaching and assessment of ethics in the postgraduate setting. Despite these differences, ethics training programs should recognise that the transition from medical students to healthcare professionals entails a longitudinal process where ethics knowledge, skills and identity continue to build and deepen over time with clinical exposure. A systematic scoping review is proposed to analyse current postgraduate medical ethics training and assessment programs in peer-reviewed literature to guide the development of a local physician training curriculum.

METHODS

With a constructivist perspective and relativist lens, this systematic scoping review on postgraduate medical ethics training and assessment will adopt the Systematic Evidence Based Approach (SEBA) to create a transparent and reproducible review.

RESULTS

The first search involving the teaching of ethics yielded 7669 abstracts with 573 full text articles evaluated and 66 articles included. The second search involving the assessment of ethics identified 9919 abstracts with 333 full text articles reviewed and 29 articles included. The themes identified from the two searches were the goals and objectives, content, pedagogy, enabling and limiting factors of teaching ethics and assessment modalities used. Despite inherent disparities in ethics training programs, they provide a platform for learners to apply knowledge, translating it to skill and eventually becoming part of the identity of the learner. Illustrating the longitudinal nature of ethics training, the spiral curriculum seamlessly integrates and fortifies prevailing ethical knowledge acquired in medical school with the layering of new specialty, clinical and research specific content in professional practice. Various assessment methods are employed with special mention of portfolios as a longitudinal assessment modality that showcase the impact of ethics training on the development of professional identity formation (PIF).

CONCLUSIONS

Our systematic scoping review has elicited key learning points in the teaching and assessment of ethics in the postgraduate setting. However, more research needs to be done on establishing Entrustable Professional Activities (EPA)s in ethics, with further exploration of the use of portfolios and key factors influencing its design, implementation and assessment of PIF and micro-credentialling in ethics practice.

[Clinical outcomes of COVID-19 cases and influencing factors in Guangdong province]

Objective: To analyze the clinical courses and outcomes of COVID-19 cases and the influencing factors in Guangdong province and provide basis for the formulation or adjustment of medical care and epidemic control strategy for COVID-19. Methods: We collected demographic data, medical histories, clinical courses and outcomes of 1 350 COVID-19 patients reported in Guangdong as of 4 March 2020 via epidemiological investigation and process tracking. Disease severity and clinical course characteristics of the patients and influencing factors of severe illness were analyzed in our study. Results: Among 1 350 cases of COVID-19 cases in Guangdong, 72 (5.3%) and 1 049 (77.7%) were mild and ordinary cases, 164 (12.1%) were severe cases, 58 (4.3%) were critical cases and 7 (0.5%) were fatal. The median duration of illness were 23 days (P(25), P(75): 18, 31 days) and the median length of hospitalization were 20 days (P(25), P(75): 15,27 days). For severe cases, the median time of showing severe manifestations was on the 12(th) day after onset (P(25), P(75): 9(th) to 15(th) days), and the median time of severe manifestation lasted for 8 days (P(25), P(75): 4, 14 days). Among 1 066 discharged/fetal cases, 36.4% (36/99) and 1.0% (1/99) of the mild cases developed to ordinary cases and severe cases respectively after admission; and 5.2% (50/968) and 0.6% (6/968) of the ordinary cases developed to severe cases, and critical cases respectively after admission. In severe cases, 11.4% developed to critical cases (10/88). The influencing factors for severe illness or worse included male (aHR=1.87, 95%CI: 1.43-2.46), older age (aHR=1.67, 95%CI: 1.51-1.85), seeking medical care on day 2-3 after onset (aHR=1.73, 95%CI: 1.20-2.50) pre-existing diabetes (aHR=1.75, 95%CI: 1.12-2.73) and hypertension (aHR=1.49, 95%CI: 1.06-2.09). Conclusions: The course of illness and length of hospitalization of COVID-19 cases were generally long and associated with severity of disease clinical outcomes. The severe cases were mainly occurred in populations at high risk. In the epidemic period, classified management of COVID-19 cases should be promoted according to needs for control and prevention of isolation and treatment for the purpose of rational allocation of medical resources.

A systematic scoping review and thematic analysis of interprofessional mentoring in medicine from 2000 to 2019

Interprofessional mentoring in palliative care sees different members of the interprofessional team providing holistic, personalised andlongitudinal mentoring support, skills training and knowledge transfer as they mentor trainees at different points along their mentoring journeys. However, gaps in practice and their risk of potential mentoring malpractice even as interprofessional mentoring use continues to grow in palliative medicine underlines the need for careful scrutiny of its characteristics and constituents in order to enhance the design, evaluation and oversight of interprofessional mentoring programmes. Hence, a systematic scoping review on prevailing accounts of interprofessional mentoring in medicine is conducted to address this gap. Using Arksey and O'Malley's (2005) methodological framework for conducting scoping reviews and identical search strategies, 6 reviewers performed independent literature reviews of accounts of interprofessional mentoring published in 10 databases. Braun and Clarke's (2006) thematic analysis approach was adopted to evaluate across different mentoring settings. A total of 11111 abstracts were identified from 10 databases, 103 full-text articles reviewed and 14 full-text articles were thematically analysed to reveal 4 themes: characterizing, implementing, evaluating and obstacles to interprofessional mentoring. Interprofessional mentoring is founded upon a respectful and collaborative mentoring relationship that thrives despite inevitable differences in individual values, ethical perspectives at different career stages within diverse working environments. This warrants effective mentor-mentee trainings, alignment of expectations, roles and responsibilities, goals and timelines, and effective oversight of the programmes. Drawing upon the data provided, an interprofessional mentoring framework is forwarded to guide the design, evaluation and oversight of the programmes.

A peer support intervention for first-time mothers: Feasibility and preliminary efficacy of the mummy buddy program

BACKGROUND

The transition to motherhood, although joyous, can be highly stressful, and the availability of professional postpartum support for mothers is often limited. Peer volunteer support programs may offer a viable and cost-effective method to provide community-based support for new mothers.

AIM

To determine the feasibility of a peer volunteer support program-The Mummy Buddy Program-in which experienced volunteer mothers are paired with, and trained to offer social support to, first-time mothers.

METHODS

Using a single-group non-randomised feasibility trial, a total of 56 experienced mothers participated in the Mummy Buddy training program, which was focused on education and practical exercises relating to the provision of various forms of social support. Experienced mothers ('Mummy Buddies') were subsequently paired with expectant first-time mothers (n=47 pairs), and were encouraged to provide support until 24-weeks postpartum.

FINDINGS

In terms of key feasibility considerations, 95.1% of Mummy Buddies felt that they were trained sufficiently to perform their role, and 85.8% of New Mothers were satisfied with the support provided by their Buddy. Analyses of preliminary efficacy (i.e., program outcomes) revealed that the first-time mothers maintained normal levels of stress and depressive symptomology, and possessed relatively strong maternal functioning, across the program duration.

CONCLUSION

The Mummy Buddy Program appears to be a feasible and potentially valuable peer volunteer support program for first-time mothers. This study provides a foundation for program expansion and for work designed to examine program outcomes-for first-time mothers, Mummy Buddies, and entire family units-within a sufficiently-powered randomised controlled trial.

[Analysis on the cluster epidemic of coronavirus disease 2019 in Guangdong Province]

Objective: Analysis of clustering characteristics of coronavirus disease 2019 (COVID-19) in Guangdong Province. Methods: The COVID-19 cases in Guangdong Province onset from January 1 to February 29, 2020 were collected from Chinese information system for disease control and prevention and Emergency Public Reporting System. Obtain the epidemiological survey data of the cluster epidemic situation, and clarify the scale of cluster epidemic situation, the characteristics of the index cases, family and non-family subsequent cases. Calculate serial interval according to the onset time of the index cases and subsequent cases, secondary attack rate based on the close contacts tracking results, the characteristics of different cases in the clustered epidemic were compared. Results: A total of 283 cluster were collected, including 633 index cases, 239 subsequent cases. Families are mainly clustered, the total number involved in each cluster is in the range of 2-27, M (P₂₅, P₇₅) are 2.0 (2.0, 4.0). During January 15 to February 29, the secondary attack rate is 2.86% (239/8 363) in Guangdong Province, the family secondary attack rate was 4.84% (276/3 697), and the non-family secondary attack rate was 1.32% (61/4 632). According to the reporting trend of the number of cases in Guangdong Province, it can be divided into four stages, the rising stage, the high platform stage, the descending stage and the low level fluctuation period. The secondary attack rate of the four stages were 3.5% (140/3 987), 2.3% (55/2 399), 2.6% (37/1 435), 1.3% (7/542), respectively. The difference was statistically significant (P=0.003). Conclusion: COVID-19 cluster mainly occurs in families in Guangdong Province. The scale of the clustered epidemic was small; the serial interval was short; and the overall secondary attack rate was low.

Impact of Caring for Terminally Ill Children on Physicians: A Systematic Scoping Review

INTRODUCTION

Caring for terminally ill children influences nurses' and allied health provider's quality of life, ability to provide personalized, dignified and empathetic care and even their concepts of personhood. In the absence of data this review utilizes the Ring Theory of Personhood (RToP) to evaluate how a physician's concept of personhood is affected caring for terminally ill children in order to better support them holistically.

METHODS

Using PRISMA Guidelines, 14 researchers carried out independent searches of PubMed, CINAHL, PsycINFO, Cochrane Library and gray literature databases for articles published between 2000 to 2019. Concurrent and independent employment of content and thematic analysis (Split Approach) was used to enhance the trustworthiness of the analysis.

RESULTS

13,424 titles and abstracts were retrieved, 188 full texts were evaluated, and 39 articles were included and analyzed. Identical categories and themes identified using the Split Approach suggest that caring for dying children in PPC impacts the physician's professional identity, clinical decision making, personal well-being and relationships. The data also suggests that the magnitude of these effects depends on the presence of protective and risk factors.

CONCLUSION

Aside from providing a novel insight into the upon the physician, this review proffers a unique approach to accounting for the presence, magnitude and influence of incoming catalysts, resultant conflicts, and protective and risk factors upon the physician's personhood. Further studies into the changes in personhood are required. Design of a personalized assessment tool based on the RToP will help direct timely, appropriate and personalized support to these physicians.

Retrospective Analysis of 61 Cases of Children Died of Viral Pneumonia

Abstract

Objective To retrospectively analyze the forensic pathological postmortem examination and clinical data of children who died of viral pneumonia in identification of cause of death cases and to discuss the clinical characteristics and pathological features of viral pneumonia in children, in order to provide reference to pathological diagnosis of viral pneumonia in children caused by 2019 novel coronavirus （2019-nCoV） infection. Methods Postmortem examination data from 61 cases of children whose causes of death were identified as viral pneumonia in recent years were collected from the Center of Forensic Identification, Southern Medical University. The gender, age, clinical symptoms and pathological features were comparatively analyzed. Results Among the 61 cases of children who died of viral pneumonia, most were within 2 years old （83.61%）, and a large proportion died within 2 weeks after the onset of the disease （91.80%）. Gross changes in postmortem examination included respiratory mucosal hyperemia, pleural effusion, pulmonary swelling, variegated pulmonary pleura and serosa, as well as focal pulmonary hemorrhage and pulmonary edema. A large proportion of sick children had enlarged mesenteric lymph nodes （83.61%） and thymic dysplasia （21.31%）. Histopathological changes included edema of alveoli and interstitial substance, pneumorrhagia，shedding of alveolar epithelial cells, serous and （or） fibrous exudation in the alveoli, formation of viral inclusions, formation of transparent membranes, infiltration of inflammatory cells that mainly consisted of macrophages and lymphocytes in interstitial substance and alveoli. Viral infections often affected the heart and gastrointestinal tract. Conclusion The clinical symptoms of children with viral pneumonia are difficult to notice, and because the immune systems of children are not fully developed and they have poor immunity, they can easily become severely ill and even die. Analyzing the forensic autopsies and the histopathological characteristics could provide reference for pathological diagnosis of viral pneumonia.

Nurturing professionalism in medical schools. A systematic scoping review of training curricula between 1990-2019

Introduction: Professionalism is an evolving, socioculturally informed multidimensional construct that influences doctor-patient relationships, patient satisfaction and care outcomes. However, despite its clinical significance there is little consistency in how professionalism is nurtured amongst medical students. To address this gap a systemic scoping review of nurturing professionalism in medical schools, is proposed.Methods: Levac's framework and the PRISMA-P 2015 checklist underpinned a 6-stage systematic review protocol. Concurrent use of Braun and Clarke's approach to thematic analysis and directed content analysis was used to identify the key elements in nurturing professionalism.Results: 13921 abstracts were identified from six databases, 854 full-text articles reviewed, and 162 full-text included articles were included. The 4 themes identified through thematic analysis are consistent with findings of the directed content analysis. These were the definition of professionalism, the approaches, content, barriers and enablers to teaching professionalism.Conclusion: Informed by a viable definition of professionalism and clear milestones nurturing professionalism nurturing professionalism begins with culturally appropriate training in clinical competence, humanistic qualities and reflective capacity. This process requires effective evaluations of professional identity formation, and the impact of the learning environment underlining the need for longitudinal assessments of the training process.

Enhancing Mentoring in Palliative Care: An Evidence Based Mentoring Framework

BACKGROUND

Growing concerns over ethical issues in mentoring in medicine and surgery have hindered efforts to reinitiate mentoring for Palliative Care (PC) physicians following the easing of COVID-19 restrictions. Ranging from the misappropriation of mentee's work to bullying, ethical issues in mentoring are attributed to poor understanding and structuring of mentoring programs, underlining the need for a consistent approach to mentoring practices.

METHODS

Given diverse practices across different settings and the employ of various methodologies, a novel approach to narrative reviews (NR)s is proposed to summarize, interpret, and critique prevailing data on novice mentoring. To overcome prevailing concerns surrounding the reproducibility and transparency of narrative reviews, the Systematic Evidenced Based Approach (SEBA) adopts a structured approach to searching and summarizing the included articles and employed concurrent content and thematic analysis that was overseen by a team of experts.

RESULTS

A total of 18 915 abstracts were reviewed, 62 full text articles evaluated and 41 articles included. Ten themes/categories were ascertained identified including Nature; Stakeholders; Relationship; Approach; Environment; Benefits; Barriers; Assessments; Theories and Definitions.

CONCLUSION

By compiling and scrutinizing prevailing practice it is possible to appreciate the notion of the mentoring ecosystem which sees each mentee, mentor, and host organization brings with them their own microenvironment that contains their respective goals, abilities, and contextual considerations. Built around competency based mentoring stages, it is possible to advance a flexible yet consistent novice mentoring framework.

[Survey on the quadrivalent influenza vaccine intention and related factors of health care workers in the Pearl River Delta region from 2015 to 2017]

Objective: To analyze the quadrivalent influenza vaccine intention of 718 health care workers (HCWs) in the Pearl River Delta region from 2015 to 2017. Method: In May 2018, 718 HCWs from the department related to the diagnosis and treatment of influenza in 17 hospitals (6 tertiary hospitals, 5 secondary hospitals and 6 primary hospitals) from Guangzhou, Jiangmen, Zhuhai and Dongguan were selected by using stratified sampling method. Questionnaire survey and face-to-face interview were used to collect the information of influenza vaccination, the intention of the quadrivalent influenza vaccine, the acceptance of free and required vaccination policies, and recommendations for increasing influenza vaccination intentions from 2015 to 2017. The multivariate logistic regression was used to analyze factors associated with the vaccination intention. Results: A total of 718 HCWs were surveyed and 147 of them were interviewed face to face. Among them, the vaccination rate of primary hospitals [17.39%(40/230)] was higher than that of other hospitals (χ(2)=15.80, P<0.05). If the vaccine could be free, 84.82% (609/718) of HCWs would like to be vaccinated. The multivariate logistic regression showed that the factors, HCWs who were aged ≥50 years (OR=3.44, 95%CI:1.43-8.28), worked in department of prevention and health care (OR=2.35, 95%CI:1.16-4.75), learned about the quadrivalent influenza vaccine (OR=2.94, 95%CI:2.08-4.18), knowed that HCWs are priority (OR=2.33, 95%CI:1.56-3.48), and had a history of trivalent influenza vaccination from 2015 to 2017 (OR=4.70, 95%CI:3.08-7.15), were associated with the vaccination intention. Conclusion: HCWs in the Pearl River Delta region had weak inclination of getting quadrivalent influenza vaccine. HCWs who were age (≥50 years old), worked in department of prevention and health care, learned about the quadrivalent influenza vaccine, knowed that HCWs are priority, and had a history of trivalent influenza vaccination from 2015 to 2017 were factors positively associated with the vaccination intention.

Evaluation of rapid influenza diagnostic tests for influenza A and B in the tropics

Rapid diagnosis of influenza is important for early treatment and institution of control measures. In developing tropical countries such as Malaysia, influenza occurs all year round, but molecular assays and conventional techniques (such as immunofluorescence and culture) for diagnosis are not widely available. Rapid influenza diagnostic tests (RIDTs) may be useful in this setting. A total of 552 fresh respiratory specimens were assessed from patients with respiratory symptoms at a teaching hospital in Kuala Lumpur, Malaysia from November 2017 to March 2018. Two digital immunoassays (DIAs), STANDARD F Influenza A/B Fluorescence Immunoassay (STANDARD F) and Sofia Influenza A + B Fluorescence Immunoassay (Sofia) and one conventional RIDT (immunochromatographic assay), SD Bioline Influenza Ag A/B/A(H1N1) Pandemic rapid test kit (SD Bioline) were evaluated in comparison with a WHO-recommended reverse transcription quantitative PCR (RT-qPCR). Of the 552 samples, influenza A virus was detected in 47 (8.5%) and influenza B virus in 7 (1.3%). The digital immunoassays STANDARD F and Sofia had significantly higher overall sensitivity rates (71.7% and 70.6%, respectively) than the conventional RIDT SD Bioline and immunofluorescence/viral culture (55.8% and 52.8%, respectively). Sensitivity rates were higher for influenza A than influenza B, and specificity rates were uniformly high, ranging from 98% to 100%. Digital readout RIDTs can be used in tropical settings with year-round influenza if PCR is unavailable.

[Analysis on risk factors for norovirus outbreaks in Guangdong province, 2008-2015]

Objective: To analyze transmission factors of norovirus outbreaks in Guangdong province during 2008-2015 and provide evidence for the prevention and control of norovirus infection. Methods: Epidemiological analysis was performed on the data of norovirus outbreaks reported in Guangdong from January 1, 2008 to December 31, 2015, which were obtained from the Public Health Emergency Management Information System of Guangdong province. The samples collected from the norovirus outbreaks were detected for norovirus by RT-PCR and the gene sequencing of the positive PCR products were performed. Results: A total of 96 norovirus outbreaks were reported in Guangdong during 2008-2015. Sixteen outbreaks were reported during 2008-2012 and 80 outbreaks were reported during 2013-2015 (83.3%). Eighty-two outbreaks (85.4%) occurred in schools. The infection routes included foodborne transmission in 39 outbreaks (40.6%), person to person transmission in 23 outbreaks (24.0%) and waterborne transmission in 8 outbreaks (7.3%). The gene sequencing results showed that variant GⅡ.4/Sydney2012 was the predominant pathogen for 6 of the 20 outbreaks (30.0%) during 2012-2013. Variant GⅡ.17 was the predominant pathogens for 33 of the 53 outbreaks (62.3%) during 2014-2015. Conclusion: The norovirus outbreaks in Guangdong during 2008-2015 were caused by foodborne and person to person transmissions of two emerging variant: GⅡ.4/Sydney2012 and GⅡ.17.

[Analysis on epidemiological characteristics of enterovirus 71 cases of hand-foot-mouth disease based on the active monitoring in Guangdong Province in 2011-2015]

Objective: To analyze the hand-foot-mouth disease (HFMD) enterovirus 71 (EV-A71) infection epidemic characteristics of Guangdong Province from 2011 to 2015. Methods: We colleted data on common cases of hand-foot-mouth disease infected with EV-A71 reported from eight sentinel hospitals in Guangdong Province from January 2011 to December 2015, through the "Guangdong Province Acute Infectious Disease Surveillance Information Platform System" , including the age and incidence of cases. Time and etiological data, etc.We also collected data on the number of reported cases of HFMD disease and the number of laboratory-confirmed cases, through the "China Disease Prevention and Control Information System" , including data on common cases of HFMD disease, data on epidemics of severe cases and deaths, and the age, onset time, and pathogens of cases. Learning data, etc.The data from two sources were used to estimate the incidence of HFMD in EV-A71 and describe its distribution characteristics.Chi-square test was used to compare the positive rate of HF-A71 infection in hand-foot-mouth disease and the difference in estimated incidence among different age groups and months. Results: Eight sentinel hospitals from 2011 to 2015 reported a total of 1 855 common cases of EV-A71 infection, of which the highest was in 2014 (31.6%, 605/1 916) and the lowest was in 2015 (6.8%, 134/1 971) (χ(2)=521.85, P<0.001).According to the Disease Surveillance Reporting Information System, 1 772 516 cases of HFMD disease were reported from 2011 to 2015 in Guangdong Province, and 1 902 cases of severe and fatal cases of EV-A71 infection.The composition ratio of EV-A71 infected was 72.6% (1 775/2 444) and 97.0% (127/131) of severe HFMD disease in Guangdong province during 2011-2015.The average annual incidence of HF-A71 infection in all age groups showed a decreasing trend with age (χ(2trend)=990 273.20, P<0.001), and it was the highest in the 1-year-old group, which was 1 697.67/100 000, and the lowest in the 4-year-old group, which was 705.46/100 000. The difference of monthly average incidence of EV-A71 infection in HF-A71 in each month was statistically significant (χ(2)=401.23, P<0.001), the highest in May at 15.51 per 100 000, and the lowest in July at 9.42 per 100 000. Conclusion: EV-A71 infection rate of ordinary HFMD varies in different years. The most severe and death cases of HFMD were EV-A71 infected. 1 year old children were the high-risk group of infected with EV-A71 HFMD. April was the epidemic months of EV-A71 HFMD infection.

[Epidemiological characteristics of influenza in Guangdong province, during winter of 2017-2018]

Objective: To understand the epidemiological characteristics of influenza in Guangdong province, during the winter of 2017-2018, to provide evidence for response to the diversity of influenza, in different seasonal patterns. Methods: Data on weekly influenza surveillance from January 2016 to April 2018, were collected in Guangdong. Information on patients with Influenza-like illness (ILI), on influenza virus positive rates and on outbreaks during the winter of 2017 to 2018, was analyzed and compared with those in spring of 2016 and summer of 2017. χ(2) test and Fisher exact test were used. Results: In the above said winter, the average percentage of visits for ILI in 28 hospitals where sentinel surveillance program had been set, was 4.99% (157 235/3 149 656), which was above the level of the same period in the previous five years. The positive rates of influenza virus among samples collected from ILI outpatients and hospitalized cases under severe acute respiratory infection (SARI) were 28.33% (2 137/7 543) and 14.93% (256/1 715), with the proportions of B (Yamagata) as 70.43% (1 505/2 137) and 73.05% (187/256) respectively. A total of 257 influenza outbreaks were reported in the winter period, with 82.49% (212/257) occurred in elementary schools. Cases aged 6-14 years occurred in winter and spring appeared of having higher positive rate than those seen in summer (P<0.05) whereas elderly cases aged 60 and above showed higher positive rate in summer than those in winter and spring two seasons (P<0.05). Conclusions: Epidemiological characteristics of influenza appeared in Guangdong province, during the winter from 2017 to 2018, were correlated to Influenza B (Yamagata). Capacity on the implementation of surveillance programs and on the coverage of vaccination should be improved and increased in order to control influenza in different epidemic seasons, in Guangzhou.

[Epidemiological characteristics of Coxsackie virus A16 caused hand foot and mouth disease cases in Guangdong province, 2012-2016]

Objective: To analyze the epidemiological characteristics of hand foot and mouth disease (HFMD) cases caused by Coxsackie virus A16 (Cox A16) in Guangdong province from 2012 to 2016. Methods: The data of mild HFMD cases caused by Cox A16 were collected from 8 sentinel hospitals in 8 prefecture-level cities in Guangdong to estimate Cox A16 infection status and its population and time distribution characteristics. Results: (1) The highest estimated incidence of Cox A16 infection was in 2014 (113.0/100 000), followed by 2016 (86.4/100 000) and 2012 (79.1/100 000), while the estimated incidence was lower in 2015 (29.0/100 000) and 2013 (28.8/100 000). (2) Cox A16 was confirmed to be the predominant pathogen causing HFMD outbreaks (54.6%, 89/163). The number of outbreaks in the year with high incidence (28 outbreaks) was 11.2 times higher than that in the year with low incidence (2.5 outbreaks). (3) Across all age groups, the annual estimated incidence of Cox A16 infection decreased with age (trend χ(2)=853 905.63, P<0.01). The incidence was highest in age group 1 year (1 449.2/100 000), followed by that in age group 3 years (1 097.0/100 000), in age group 2 years (1 083.5/100 000), in age group 4 years (687.8/100 000) and in age group 0 year (604.9/100 000). Among the age groups <12 months, the estimated incidence increased with age (trend χ(2)=5 541.77, P<0.01), which was highest in age group 11-months (2 105.1/100 000), followed by that in age groups 10-months (1 448.6/100 000), 9-months (938.3/100 000), 8-months (703.3/100 000) and 6-months (664.6/100 000). (4) The annual incidence peak was during May (143.9/100 000)-June (131.5/100 000). Conclusion: The prevalence of Cox A16 infection differed with year in Guangdong during 2012-2016. When the incidence of Cox A16 infection was high, more outbreaks occurred. The prevalence occurred mainly in nurseries and kindergartens from May to June each year. Children aged 0-4 years were the high risk group for Cox A16 infection, children aged 6-11 months were at high risk for Cox A16 infection.

Analysis of serum microRNA expression in male workers with occupational noise-induced hearing loss

Occupational noise-induced hearing loss (ONIHL) is a prevalent occupational disorder that impairs auditory function in workers exposed to prolonged noise. However, serum microRNA expression in ONIHL subjects has not yet been studied. We aimed to compare the serum microRNA expression profiles in male workers of ONIHL subjects and controls. MicroRNA microarray analysis revealed that four serum microRNAs were differentially expressed between controls (n=3) and ONIHL subjects (n=3). Among these microRNAs, three were upregulated (hsa-miR-3162-5p, hsa-miR-4484, hsa-miR-1229-5p) and one was downregulated (hsa-miR-4652-3p) in the ONIHL group (fold change >1.5 and P_bon value <0.05). Real time quantitative PCR was conducted for validation of the microRNA expression. Significantly increased serum levels of miR-1229-5p were found in ONIHL subjects compared to controls (n=10 for each group; P<0.05). A total of 659 (27.0%) genes were predicted as the target genes of miR-1229-5p. These genes were involved in various pathways, such as mitogen-activated protein kinase (MAPK) signaling pathway. Overexpression of miR-1229-5p dramatically inhibited the luciferase activity of 3′ UTR segment of MAPK1 (P<0.01). Compared to the negative control, HEK293T cells expressing miR-1229-5p mimics showed a significant decline in mRNA levels of MAPK1 (P<0.05). This preliminary study indicated that serum miR-1229-5p was significantly elevated in ONIHL subjects. Increased miR-1229-5p may participate in the pathogenesis of ONIHL through repressing MAPK1 signaling.

[Let-7 miRNA silencing promotes Kaposi's sarcoma-associated herpesvirus lytic replication via activating mitogen-activated protein kinase kinase kinase kinase 4 and its downstream factors]

OBJECTIVE

To explore the effect of let-7 miRNA silencing on Kaposi's sarcoma-associated herpesvirus (KSHV) lytic replication and the underling mechanism.

METHODS

The pEGFP-C2-let-7 sponge vector was transfected into BCBL-1 and 293T cells with Lipofectamine 2000 to silence the expression of let-7 miRNAs. Quantitative real-time PCR (qRT-PCR) was used to quantify the expression of let-7 miRNAs, the transcriptional levels of mitogen-activated protein kinase kinase kinase kinase 4 (MAP4K4), cyclooxygenase-2 (COX-2) and matrix metalloproteinase 13 (MMP-13), and the DNA copy numbers of KSHV open reading frame 50 (ORF50) and open reading frame 72 (ORF72). Western blot was used to detect the total and phosphorylated protein levels of MAP4K4, COX-2, extracellular regulated protein kinases (ERK1/2), c-Jun N-terminal kinase (JNK) and p38 MAPK.

RESULTS

The expression of let-7 miRNAs was dramatically decreased in the let-7 sponge transfected BCBL-1 and 293T cells compared with that in the vector-transfected cells (P<0.05 for all). The gene copy number and mRNA transcriptional level of KSHV ORF50 were significantly increased in the let-7 sponge transfected BCBL-1 cells compared with that in the vector-transfected cells (1.00±0.10 vs. 2.33±0.18 and 1.08±0.48 vs 3.22±0.27, respectively,P<0.001 for both). The gene copy number and mRNA transcriptional level of KSHV ORF72 were also significantly increased in let-7 sponge transfected BCBL-1 cells compared with those in the vector-transfected cells(1.07±0.49 vs 1.67±0.45 and 1.01±0.19 vs 1.54±0.11, respectively,P<0.05 for both). Furthermore, the mRNA transcriptional levels of MAP4K4, COX-2 and MMP-13 were significantly increased in the let-7 sponge transfected BCBL-1 cells compared with those in the vector-transfected cells (1.00±0.05 vs 5.73±0.96, 1.00±0.05 vs 2.68±0.19, 1.00±0.02 vs 2.69±0.25, respectively,P<0.001 for all). Let-7 miRNAs silencing also increased the protein expression levels of MAP4K4, COX-2 and phospho-ERK1/2, while the phospho-JNK and phospho-p38 were not changed in the BCBL-1 and 293T cells.

CONCLUSIONS

Let-7 silencing may activate the replication of KSHV, possibly through up-regulating MAP4K4 and its downstream molecules COX-2, MMP-13, and phosphorylation of ERK1/2, finally results in the progression of Kaposi sarcoma.

Cancer classification based on gene expression using neural networks

Based on gene expression, we have classified 53 colon cancer patients with UICC II into two groups: relapse and no relapse. Samples were taken from each patient, and gene information was extracted. Of the 53 samples examined, 500 genes were considered proper through analyses by S-Kohonen, BP, and SVM neural networks. Classification accuracy obtained by S-Kohonen neural network reaches 91%, which was more accurate than classification by BP and SVM neural networks. The results show that S-Kohonen neural network is more plausible for classification and has a certain feasibility and validity as compared with BP and SVM neural networks.

A compact time-of-flight mass spectrometer for ion source characterization

A compact time-of-flight mass spectrometer with overall dimension of about 413 × 250 × 414 mm based on orthogonal injection and angle reflection has been developed for ion source characterization. Configuration and principle of the time-of-flight mass spectrometer are introduced in this paper. The mass resolution is optimized to be about 1690 (FWHM), and the ion energy detection range is tested to be between about 3 and 163 eV with the help of electron impact ion source. High mass resolution and compact configuration make this spectrometer useful to provide a valuable diagnostic for ion spectra fundamental research and study the mass to charge composition of plasma with wide range of parameters.

Combined effects of magnetic interaction and domain wall pinning on the coercivity in a bulk Nd₆₀Fe₃₀Al₁₀ ferromagnet

Understanding the coercivity mechanism has a substantial impact on developing novel permanent materials. However, the current coercivity mechanisms used widely in permanent alloys cannot explain well the amorphous phase produced hard magnetic behavior of Nd-based bulk amorphous alloys (BAAs). Here, we propose that the coercivity in as-cast Nd₆₀Fe₃₀Al₁₀ alloy is from the combination of magnetic interaction and strong pinning of domain walls. Moreover, the role of domain wall pinning is less affected after crystallization, while the magnetic interaction is dependent on the annealing temperature. Our findings give further insight into the coercivity mechanism of Nd-based bulk ferromagnets and provide a new idea to design prospective permanent alloys with coercivity from the combination of magnetic interaction and pinning of domain walls.

[Bovine alpha-sl-casein gene sequences direct expression of a variant of human tissue plasminogen activator in the milk of transgenic mice]

The fusion gene containing the promoter of casein gene, LAtPA minigene and 3' flanking sequences of casein gene was introduced into the fertilized eggs of mice by microinjection. Five positive transgenic mice were obtained. The concentration of LAtPA in the milk of one female transgenic mouse is 0.18 microgram/ml. This result showed that the LAtPA minigene could correctly express the bioactive LAtPA in the milk of the transgenic mouse under the control of the regulatory elements of the casein gene.

[New advances and future perspectives in mammal cloning]

To the great extent, the study and application of transgenic animal are restricted by the inherent limitation of pronuclear microinjection. Recently, the rapid progresses in gene targeting and cloning of somatic cells have shown that the combination of these two technologies will become a virtual way to producing large transgenic animals.

[Gene analysis of blast resistance in an indica variety Digu]

Digu is one of the important genetic resources in rice breeding for resistance to blast disease in China. In this study, the disease resistance identification in the parental varieties and the population F1, F2 and B1F1 from the crosses involving Digu and four susceptible varieties was carried out by inoculation with two Chinese blast strains, ZB13, and ZB15. The results demonstrated that Digu had one dominant gene Pi-d(t) to ZB13, which had been reported by Li SG. The F2 populations of Digu and other ten different varieties with known resistance genes were inoculated with strains ZB13 and the results further demonstrated that blast resistance of Digu to strain ZB13 was controlled by one dominant resistance gene.

Role of lysine-54 in determining cofactor specificity and binding in human dihydrofolate reductase

Lysine-54 of human dihydrofolate reductase (hDHFR) appears to be involved in the interaction with the 2'-phosphate of NADPH and is conserved as a basic residue in other species. Studies have suggested that in Lactobacillus casei dihydrofolate reductase Arg-43, the homologous residue at this position, plays an important role in the binding of NADPH and in the differentiation of Km values for NADPH and NADH. A Lys-54 to Gln-54 mutant (K54Q) of hDHFR has been constructed by oligodeoxynucleotide-directed mutagenesis in order to study the role of Lys-54 in differentiating Km and Kcat values for NADPH and NADH as well as in other functions of hDHFR. The purpose of this paper is to delineate in quantitative terms the magnitude of the effect of the Lys-54 to Gln-54 replacement on the various kinetic parameters of hDHFR. Such quantitative effects cannot be predicted solely on the basis of X-ray structures. The Km for NADPH for the K54Q mutant enzyme is 58-fold higher, while the Km for NADH for K54Q is only 3.9-fold higher than that of the wild type, indicating that the substitution of Lys-54 with Gln-54 decreases the apparent affinity of the enzyme for NADPH dramatically, but has a lesser effect on the apparent affinity for NADH.(ABSTRACT TRUNCATED AT 250 WORDS)

The importance of loop region residues 40-46 in human dihydrofolate reductase as revealed by site-directed mutagenesis

Site-directed mutagenesis has been used to delete 2 residues (Gly45-Lys46) from a flexible "loop" region between residues 40 and 46 of human dihydrolate reductase. Steady-state kinetic studies show that the Km values for the deletion mutant enzyme for both dihydrofolate and nicotinamide adenine dinucleotide phosphate (reduced) (NADPH) as well as the pH rate profile are virtually identical to that of the wild type. In contrast, the Vmax value of the mutant enzyme is decreased 2.5-fold. The results suggest that the loop region may play a role in the catalytic efficiency but not necessarily in the binding of substrates. Agents such as KCl, urea, and organomercurials at concentrations which show activating effects on the wild-type human dihydrofolate reductase have little or no effect on the deletion mutant. Competitive enzyme-linked immunosorbent assay experiments using peptide-specific antibodies against cyanogen bromide fragments generated from human dihydrofolate reductase show that the binding of folate, NADPH, and methotrexate, either in binary or in ternary complexes with the wild-type enzyme, causes a striking reduction in the binding of the antibodies. Compared with wild type, the binding of these ligands with the deletion mutant enzyme causes much less inhibition (2-16-fold less) in the binding of all three antibodies. The altered properties of the mutant enzyme can be explained on the basis of a need for the flexible loop 40-46 for reversible protein unfolding during activation and also for conformational changes induced by ligand binding, thus "communicating" the effects of ligand binding.

Mapping the antigenic epitopes of human dihydrofolate reductase by systematic synthesis of peptides on solid supports

All of the 181 possible overlapping hexapeptides as well as 179 octapeptides covering the amino acid sequence of human dihydrofolate reductase (hDHFR) were synthesized on polyethylene supports. The synthetic procedure of Geysen et al. (Geysen, H. M., Rodda, S. J., Mason, T. J., Tribbick, G., and Schoofs, P. G. (1987) J. Immunol. Methods 102, 259-274) was modified to obtain up to 100 nmol of peptide on each pin. Peptides constituting antigenic epitopes on hDHFR were identified by examining the binding of antibodies raised against both native and denatured hDHFR to these peptides by enzyme-linked immunosorbent assay. The peptides bound in a similar pattern to polyclonal antibodies against both native and denatured dihydrofolate reductase (DHFR). Six major epitopes were located corresponding to residues 27-33, 45-51, 67-74, 133-139, 153-158, and 176-181 using both hexapeptides and octapeptides. An additional epitope, constituting residues 14-21, was found by the use of octapeptides. Most of the epitopes are hydrophilic and reside largely in "loop" regions at the boundaries of secondary structural elements of hDHFR. This observation is consistent with our previous results which suggested that ligand binding at the active site of the enzyme can cause a dramatic reduction in antibody binding to DHFR due to conformational constraints in flexible loop regions in various parts of the molecule. The similarity of the immunogenic profiles of native versus denatured hDHFR indicates that the two forms of the antigen share the same amino acid sequence-specific epitopes. Competitive enzyme-linked immunosorbent assay showed that the binding of anti-hDHFR antiserum to both native and denatured hDHFR was inhibited by approximately 30% by the seven antigenic peptides, indicating that a significant proportion of the antibodies elicited by this enzyme is specific for short peptides. Besides revealing the antigenic structure of DHFR our results provide a rational basis for the design of mutant DHFRs to study the importance of loop residues in the conformational dynamics of the enzyme.

Effects of conversion of an invariant tryptophan residue to phenylalanine on the function of human dihydrofolate reductase

The binding site residue Trp-24 is conserved in all vertebrate and bacterial dihydrofolate reductases of known sequence. To determine its effects on enzyme properties, a Trp-24 to Phe-24 mutant (W-24-F) of human dihydrofolate reductase has been constructed by oligodeoxynucleotide site-directed mutagenesis. The W-24-F mutant enzyme appears to have a more open or flexible conformation as compared to the wild-type human dihydrofolate reductase on the basis of results of a number of studies. These studies include competitive ELISA using peptide-specific antibodies against human dihydrofolate reductase, thermal stability, and protease susceptibility studies of both mutant W-24-F and wild-type enzymes. It is concluded that Trp-24 is important for maintaining the structural integrity of the native enzymes. Changes in relative fluorescence quantum yield indicate that Trp-24 is buried and its fluorescence quenched relative to the other two tryptophan residues in the wild-type human reductase. Kinetic studies indicate that kcat values for W-24-F are increased in the pH range of 4.5-8.5 with a 5-fold increase at pH 7.5 as compared to the wild-type enzyme. However, the catalytic efficiency of W-24-F decreases rapidly as the pH is increased from 7.5 to 9.5. The Km values for dihydrofolate are also increased for W-24-F in the pH range of 4.5-9.5 with a 30-fold increase at pH 7.5, while the Km value for NADPH increases only ca. 1.4-fold at pH 7.5 as compared to the wild type.(ABSTRACT TRUNCATED AT 250 WORDS)

Ligand-induced structural constraints in human dihydrofolate reductase revealed by peptide-specific antibodies

Peptides from human dihydrofolate reductase (DHFR) generated by cyanogen bromide cleavage and corresponding to residues 15-52, 53-111, 112-125, and 140-186 (carboxyl terminus) were purified and used to immunize rats. Titration of the immune sera against denatured human DHFR by solid-phase immunoassay showed that peptides 15-52 and 140-186 were relatively highly immunogenic, unlike the native enzyme which is most immunogenic in the sequence 53-111. The antisera were specific for the corresponding peptides used for immunization. Antibodies to peptides 15-52, 53-111, and 140-186 cross-reacted with native human DHFR in solution in competition assays. However, the binding of nicotinamide adenine dinucleotide phosphate (reduced) (NADPH) and the inhibitors folate and methotrexate, both in binary and in ternary complexes with the enzyme, caused a striking reduction in binding of antibody. Using a sensitive radioactive assay, it was found that antisera to peptides 15-52 and 140-186, both of which exhibited a high antibody titer, caused significant inhibition of DHFR. Because peptide 140-186 does not include any active-site residues, it is concluded that at least in this case all the antibodies bound to regions outside the active site. Since comparison of the X-ray structures of the chicken liver DHFR holoenzyme with the apoenzyme reveals no changes in secondary structural elements (alpha-helices and beta-sheets), the reduction in antibody binding to DHFR-ligand complexes must not involve epitopes within these structures.(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibition of murine thymidylate synthase and human dihydrofolate reductase by 5,8-dideaza analogues of folic acid and aminopterin

A series of 5,8-dideaza analogues of folic acid, isofolic acid, aminopterin, and isoaminopterin were evaluated for inhibition of thymidylate synthase, TS, from mouse L1210 leukemia cells with 10-propargyl-5,8-dideazafolic acid, CB3717, 4a, as the reference inhibitor. These compounds were also tested as inhibitors of human dihydrofolate reductase, DHFR, obtained from WIL2 cells. None of the analogues studied were as potent as 4a toward TS; however, 9-methyl-5,8-dideazaisoaminopterin, 6d, was only 2.5-fold less effective. Compound 4a was prepared by direct alkylation of the di-tert-butyl ester of 5,8-dideazafolic acid followed by hydrolysis of the resulting diethyl ester, which resulted from concomitant transesterification. It was found to be identical with a sample of 4a prepared by earlier methodology by using a variety of spectroscopic techniques. Its isomer, 9-propargyl-5,8-dideazaisofolic acid, 4b, which was synthesized by an analogous approach, was found to be dramatically less inhibitory toward TS than 4a. Each of the 2,4-diamino derivatives, including those possessing an allyl or propargyl group at N9, was an excellent inhibitor of DHFR, having a level of potency similar to that of methotrexate, MTX. However, many of these 5,8-dideazaaminopterin analogues were far more inhibitory toward TS than MTX.