User-Friendly Chatbot to Mitigate the Psychological Stress of Older Adults During the COVID-19 Pandemic: Development and Usability Study

BACKGROUND

To safeguard the most vulnerable individuals during the COVID-19 pandemic, numerous governments enforced measures such as stay-at-home orders, social distancing, and self-isolation. These social restrictions had a particularly negative effect on older adults, as they are more vulnerable and experience increased loneliness, which has various adverse effects, including increasing the risk of mental health problems and mortality. Chatbots can potentially reduce loneliness and provide companionship during a pandemic. However, existing chatbots do not cater to the specific needs of older adult populations.

OBJECTIVE

We aimed to develop a user-friendly chatbot tailored to the specific needs of older adults with anxiety or depressive disorders during the COVID-19 pandemic and to examine their perspectives on mental health chatbot use. The primary research objective was to investigate whether chatbots can mitigate the psychological stress of older adults during COVID-19.

METHODS

Participants were older adults belonging to two age groups (≥65 years and <65 years) from a psychiatric outpatient department who had been diagnosed with depressive or anxiety disorders by certified psychiatrists according to the Diagnostic and Statistical Manual of Mental Disorders (Fifth Edition) (DSM-5) criteria. The participants were required to use mobile phones, have internet access, and possess literacy skills. The chatbot's content includes monitoring and tracking health data and providing health information. Participants had access to the chatbot for at least 4 weeks. Self-report questionnaires for loneliness, depression, and anxiety were administered before and after chatbot use. The participants also rated their attitudes toward the chatbot.

RESULTS

A total of 35 participants (mean age 65.21, SD 7.51 years) were enrolled in the trial, comprising 74% (n=26) female and 26% (n=9) male participants. The participants demonstrated a high utilization rate during the intervention, with over 82% engaging with the chatbot daily. Loneliness significantly improved in the older group ≥65 years. This group also responded positively to the chatbot, as evidenced by changes in University of California Los Angeles Loneliness Scale scores, suggesting that this demographic can derive benefits from chatbot interaction. Conversely, the younger group, <65 years, exhibited no significant changes in loneliness after the intervention. Both the older and younger age groups provided good scores in relation to chatbot design with respect to usability (mean scores of 6.33 and 6.05, respectively) and satisfaction (mean scores of 5.33 and 5.15, respectively), rated on a 7-point Likert scale.

CONCLUSIONS

The chatbot interface was found to be user-friendly and demonstrated promising results among participants 65 years and older who were receiving care at psychiatric outpatient clinics and experiencing relatively stable symptoms of depression and anxiety. The chatbot not only provided caring companionship but also showed the potential to alleviate loneliness during the challenging circumstances of a pandemic.

Potential Mobile Health Applications for Improving the Mental Health of the Elderly: A Systematic Review

The rapid aging of the global population presents challenges in providing mental health care resources for older adults aged 65 and above. The COVID-19 pandemic has further exacerbated the global population's psychological distress due to social isolation and distancing. Thus, there is an urgent need to update scholarly knowledge on the effectiveness of mHealth applications to improve older people's mental health. This systematic review summarizes recent literature on chatbots aimed at enhancing mental health and well-being. Sixteen papers describing six apps or prototypes were reviewed, indicating the practicality, feasibility, and acceptance of chatbots for promoting mental health in older adults. Engaging with chatbots led to improvements in well-being and stress reduction, as well as a decrement in depressive symptoms. Mobile health applications addressing these studies are categorized for reference.

[Clinicopathological features of low-grade oncocytic renal tumor (CD117-negative, cytokeratin 7-positive): report of seven cases]

Objective: To explore clinicopathological features of low-grade oncocytic tumor (LOT) of the kidney and to analyze its relationship to hybrid oncocytic/chromophobe tumor (HOCT) of the kidney, renal oncocytoma (RO), and chromophobe renal cell carcinoma (chRCC). Methods: Seven LOTs were identified from the pathologic archives of two hospitals, including Xiangya Hospital (5 cases) and the Second Xiangya Hospital (2 cases) of Central South University between 2012 and 2019. Clinical data of the LOTs were collected. The tumor morphology was analyzed and immunohistochemistry was performed. Results: All LOTs occurred in adults, aged from 49 to 72 years (median 56.0 years, mean 60.7 years). The tumor size ranged from 2.5 to 6.0 cm (median 4.3 cm, mean 4.3 cm). There were three male and four female patients. Three cases occurred in the left kidney and four in the right. All the tumors were solitary lesions without the clinicopathologic background of Birt-Hogg-Dubé (BHD) syndrome or oncocytosis. Five patients had available follow-up data (follow-up period 23-95 months, median 69.0 months, mean 64.6 months) and all were alive without disease. Microscopically, all LOTs were well-circumscribed (7/7). Three LOTs were partly encapsulated. The tumors demonstrated a predominant growth pattern comprising prominently compact small nests surrounded by delicately branching thin-walled blood vessels, imparting an organoid architecture (7/7), but variable numbers of glandular or gland-like structures were often seen among the small nests (7/7). There were frequently areas with loose, edematous stroma, and the tumor cells exhibited reticular, trabecular, or single cell arrangements (6/7). Focal hemorrhage was also commonly present in both compact and loose areas (5/7). In addition, focally cystic formation and ossification occurred in the compact area of one case and in the loose area of another case. The tumor cells in LOT showed intermediate cytologic characteristics between RO and chRCC, including abundantly eosinophilic granular cytoplasm, ovoid to round nuclei with mostly smooth contours, discernable small nucleoli (RO features), frequently delicate perinuclear halos, and occasional binucleation (chRCC features). The tumors were typically CK7-positive and CD117-negative (7/7), and variable staining for PAX8 (5/7), P504s (2/7), and vimentin (1/7). They were negative for CK20, CD10 and FOXI1. All tumors retained SDHB immunostaining. Conclusions: LOT is a rare and indolent oncocytic renal tumor with homogeneously intermediate cytologic features between RO and chRCC. There are some clinicopathologic overlaps between LOT and sporadic HOCT. The distinctive morphology and immunophenotype of LOT suggest that it is potentially a distinct tumor entity.

Spammer Group Detection Using Machine Learning Technology for Observation of New Spammer Behavioral Features

Recently, the rapid growth in the number of customer reviews on e-commence platforms and in the amount of user-generated content has begun to have a profound impact on customer purchasing decisions. To counter the negative impact of social media marketing, some firms have begun hiring people to generate fake reviews which either promote their own products or damage their competitor's reputation. This study proposes a framework, which takes advantage of both supervised and unsupervised learning techniques, for the observation of behaviors among spammers. Then, based on the behavior of participants on web forums, the authors build up a post-reply network. The main focus is on the behavior-related features of the reviews, their propagation, and their popularity. The primary objective of this study is to build an effective online spammer detection model and the method detailed in this work can be used to improve the performance of spammer detection models. An experiment is carried out with a real dataset, the results of which indicate that these new features are important for identifying spammers. Finally, random walk clustering is applied to investigate the post-reply network. Some interesting and important features are observed in the interactions between a group of spammers which could be subjected to further research.

Vertical Lamellae Formed by Two-Step Annealing of a Rod-Coil Liquid Crystalline Block Copolymer Thin Film

Silicon-containing block copolymer thin films with high interaction parameter and etch contrast are ideal candidates to generate robust nanotemplates for advanced nanofabrication, but they typically form in-plane oriented microdomains as a result of the dissimilar surface energies of the blocks. Here, we describe a two-step annealing method to produce vertically aligned lamellar structures in thin film of a silicon-containing rod-coil thermotropic liquid crystalline block copolymer. The rod-coil block copolymer with the volume fraction of the Si-containing block of 0.22 presents an asymmetrical lamellar structure in which the rod block forms a hexatic columnar nematic liquid crystalline phase. A solvent vapor annealing step first produces well-ordered in-plane cylinders of the Si-containing block, then a subsequent thermal annealing promotes the phase transition from in-plane cylinders to vertical lamellae. The pathways of the order-order transition were examined by microscopy and in situ using grazing incidence small-angle X-ray scattering and wide-angle X-ray scattering.

Imparting Superhydrophobicity with a Hierarchical Block Copolymer Coating

A robust and transparent silica-like coating that imparts superhydrophobicity to a surface through its hierarchical multilevel self-assembled structure is demonstrated. This approach involves iterative steps of spin-coating, annealing, and etching of polystyrene-block-polydimethylsiloxane block copolymer thin films to form a tailored multilayer nanoscale topographic pattern with a water contact angle up to 155°. A model based on the hierarchical topography is developed to calculate the wetting angle and optimize the superhydrophobicity, in agreement with the experimental trends, and explaining superhydrophobicity arising through the combination of roughness at different lengthscales. Additionally, the mechanical robustness and optically passive properties of the resulting hydrophobic surfaces are demonstrated.

Core-Shell and Zigzag Nanostructures from a Thin Film Silicon-Containing Conformationally Asymmetric Triblock Terpolymer

The self-assembly of multiblock copolymers generates diverse hierarchical nanostructures and greatly extends the range of microdomain geometries beyond those produced by diblock copolymers. We report the synthesis of a conformationally asymmetric ABC triblock terpolymer in which the end blocks are a mesogen-jacketed liquid crystalline polymer and poly(dimethylsiloxane), respectively, and its self-assembly under mixed solvent vapor annealing forms a range of sphere, cylinder, and perforated lamellar core-shell morphologies, as well as stacked multilevel structures. Sub-7 nm diameter SiO_x nanopatterns were generated by selective plasma etching of the small volume fraction Si-containing core block giving a line/space ratio of ∼1:4. Moreover, the conformational asymmetry of this terpolymer leads to zigzag cylinders on a flat substrate and stable cylinder alignment transverse to template sidewalls within lithographically patterned trenches.

Metal-Organic Framework MIL-101-NH2-Supported Acetate-Based Butylimidazolium Ionic Liquid as a Highly Efficient Heterogeneous Catalyst for the Synthesis of 3-Aryl-2-oxazolidinones

A novel heterogeneous catalyst, the ionic liquid (IL) of 1-butyl-3-methylimidazolium acetate (BmimOAc) immobilized on MIL-101-NH₂, denoted as IL(OAc^-)-MIL-101-NH₂, was prepared by the "ship-in-a-bottle" strategy. The IL of BmimOAc was prepared in the MIL-101-NH₂ nanocages primordially, in which the condensation product of MIL-101-NH₂'s amine group with 1,1'-carbonyldiimidazole (CDI) reacted with 1-bromo butane, and then the intermediate exchanged with potassium acetate. The structure and physicochemical properties of IL(OAc^-)-MIL-101-NH₂ were characterized by powder X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, DRS UV-vis, nitrogen adsorption-desorption, and elemental analysis. The results indicated that BmimOAc was anchored in the MIL-101-NH₂ skeleton via the acylamino group and confined in the nanocages in the form of a single molecule. The composite material of IL(OAc^-)-MIL-101-NH₂ exhibited excellent catalytic activity and catalytically synthesized 3-aryl-2-oxazolone in an excellent yield of 92%. It can be reused up to six times without noteworthy loss of its activity and demonstrated distinct size-selective property for substrates. It was conjectured that the diffusion kinetics of reactants could be controlled by the aperture size of the metal-organic framework support.

Self-assembly of a silicon-containing side-chain liquid crystalline block copolymer in bulk and in thin films: kinetic pathway of a cylinder to sphere transition

The self-assembly of a high-χ silicon-containing side-chain liquid crystalline block copolymer (LC BCP) in bulk and in thin films is reported, and the structural transition process from the hexagonally packed cylinder (HEX) to the body-centered cubic structure (BCC) in thin films was examined by both reciprocal and real space experimental methods. The block copolymer, poly(dimethylsiloxane-b-11-(4'-cyanobiphenyl-4-yloxy)undecylmethacrylate) (PDMS-b-P(4CNB11C)MA) with a molecular weight of 19.5 kg mol-1 and a volume fraction of PDMS 27% self-assembled in bulk into a hierarchical nanostructure of sub-20 nm HEX cylinders of PDMS with the P(4CNB11C)MA block exhibiting a smectic LC phase with a 1.61 nm period. The structure remained HEX as the P(4CNB11C)MA block transformed to an isotropic phase at ∼120 °C. In the thin films, the PDMS cylindrical microdomains were oriented in layers parallel to the substrate surface. The LC block formed a smectic LC phase which transformed to an isotropic phase at ∼120 °C, and the microphase-separated nanostructure transformed from HEX to BCC spheres at ∼160 °C. The hierarchical structure as well as the dynamic structural transition of the thin films were characterized using in situ grazing-incidence small-angle X-ray scattering and grazing-incidence wide-angle X-ray scattering. The transient morphologies from the HEX to BCC structure in thin films were captured by scanning electron microscopy and atomic force microscopy, and the transition pathway was described.

Templated Self-Assembly of a PS- Branch-PDMS Bottlebrush Copolymer

The self-assembly of block copolymers (BCPs) with novel architectures offers tremendous opportunities in nanoscale patterning and fabrication. Here, the thin film morphology, annealing kinetics, and topographical templating of an unconventional Janus-type "PS- branch-PDMS" bottlebrush copolymer (BBCP) are described. In the Janus-type BBCP, each segment of the bottlebrush backbone connects two immiscible side chain blocks. Thin films of a Janus-type BBCP with M_n = 609 kg/mol exhibited 22 nm period cylindrical microdomains with long-range order under solvent vapor annealing, and the effects of as-cast film thickness, solvent vapor pressure, and composition of the binary mixture of solvent vapors are described. The dynamic self-assembly process was characterized using in situ grazing-incidence X-ray scattering. Templated self-assembly of the BBCP within lithographically patterned substrates was demonstrated, showing distinct pattern orientation and dimensions that differ from conventional BCPs. Self-consistent field theory is used to elucidate details of the templated self-assembly behavior within confinement.

Double-Layer Morphologies from a Silicon-Containing ABA Triblock Copolymer

A combined experimental and self-consistent-field theoretical (SCFT) investigation of the phase behavior of poly(stryrene- b-dimethylsiloxane- b-styrene) (PS- b-PDMS- b-PS, or SDS32) thin films during solvent vapor annealing is presented. The morphology of the triblock copolymer is described as a function of the as-cast film thickness and the ratio of two different solvent vapors, toluene and heptane. SDS32 formed terraced bilayer morphologies even when the film thickness was much lower than the commensurate thickness. The morphology transitioned between bilayer cylinders, bilayer perforated lamellae, and bilayer lamellae, including mixed structures such as a perforated lamella on top of a layer of in-plane cylinders, as the heptane fraction during solvent annealing increased. SCFT modeling showed the same morphological trends as a function of the block volume fraction. In comparison with diblock PS- b-PDMS with the same molecular weight, the SDS32 offers a simple route to produce a diversity of well-ordered bilayer structures with smaller feature sizes, including the formation of bilayer perforated lamellae over a large process window.

Morphology, directed self-assembly and pattern transfer from a high molecular weight polystyrene-block-poly(dimethylsiloxane) block copolymer film

The self-assembly of block copolymers with large feature sizes is inherently challenging as the large kinetic barrier arising from chain entanglement of high molecular weight (MW) polymers limits the extent over which long-range ordered microdomains can be achieved. Here, we illustrate the evolution of thin film morphology from a diblock copolymer of polystyrene-block-poly(dimethylsiloxane) exhibiting total number average MW of 123 kg mol^-1, and demonstrate the formation of layers of well-ordered cylindrical microdomains under appropriate conditions of binary solvent mix ratio, commensurate film thickness, and solvent vapor annealing time. Directed self-assembly of the block copolymer within lithographically patterned trenches occurs with alignment of cylinders parallel to the sidewalls. Fabrication of ordered cobalt nanowire arrays by pattern transfer was also implemented, and their magnetic properties and domain wall behavior were characterized.

UV-solvent annealing of PDMS-majority and PS-majority PS-b-PDMS block copolymer films

The response of polystyrene-block-poly(dimethylsiloxane) (PS-b-PDMS) thin films to UV exposure during solvent vapor annealing is described, in order to improve their applicability in nanolithography and nanofabrication. Two BCPs were examined, one with the PS block as majority (f _PS = 68%, M _n = 53 kg mol^-1), the other with PDMS block as majority (f _PDMS = 67%, M _n = 44 kg mol^-1). A 5 min UV irradiation was applied during solvent vapor annealing which led to both partial crosslinking of the polymer and a small increase in the temperature of the annealing chamber. This approach was effective for improving the correlation length of the self-assembled microdomain arrays and in limiting subsequent flow of the PDMS in the PDMS-majority BCP to preserve the post-anneal morphology. Ordering and orientation of microdomains were controlled by directed self-assembly of the BCPs in trench substrates. Highly-ordered perpendicular nanochannel arrays were obtained in the PDMS-majority BCP.

Thermo-Solvent Annealing of Polystyrene-Polydimethylsiloxane Block Copolymer Thin Films

A combined thermal and solvent vapor annealing process for block copolymer self-assembly is demonstrated. Films of cylinder-forming poly(styrene-b-dimethylsiloxane) (SD45, 45.5 kg/mol, f_PDMS = 31%) were preheated for 2 min above the glass transition temperature of both blocks, followed by immediate introduction into a chamber containing room temperature saturated vapors of toluene and n-heptane. After quenching in air, microdomains had better order than those obtained from thermal or solvent annealing alone. The short time during which the film is both heated and exposed to solvent vapor played an important role in determining the final morphology.

Uses and abuses of paediatric electroencephalography

OBJECTIVE

To investigate whether requests for standard paediatric electroencephalograms accord with guideline recommendations, subsequent changes in clinical management according to reported results, and extent to which the service meets waiting time targets.

DESIGN

Case series.

SETTING

Regional hospital, Hong Kong.

PATIENTS

All patients aged less than 18 years who underwent electroencephalography between December 2009 and February 2010.

MAIN OUTCOME MEASURES

Appropriateness of the electroencephalogram request and the impact of its findings on clinical management.

RESULTS

A total of 109 patients were recruited, but requests for standard electroencephalograms were considered 'inappropriate' with respect to guidelines in 44% of the patients, of which 50% were made to diagnose 'funny turns'. The standard electroencephalogram contributed to the diagnosis or management in only 28% of patients. In all of the latter, the request for an electroencephalogram had been appropriate. Nonspecialists made referrals for 86% of the patients. Inadequate information was provided in 66% of the requests. Standard electroencephalograms were performed within guideline targets, the wait being less than 4 weeks in 95% of requests.

CONCLUSION

An effective electroencephalogram service was being provided, though abuses were common. These were mainly because of misconceptions regarding the role and limitations of standard electroencephalograms. Through an educative, non-confrontational approach, and with time to explain guideline recommendations to clinicians, sustainable change in practice could be achieved so as to benefit patients, clinicians, and service provision.

Hemangioma of the diaphragm presenting with cardiac tamponade

We report a rare form of presentation of diaphragmatic hemangioma in a neonate. The patient presented with pericardial effusion and cardiac tamponade, requiring tapping of the pericardial effusion and subsequent en-bloc resection of the hemangioma with diaphragmatic reconstruction.

Giant myxoma causing right ventricular outflow tract obstruction

Atrial cardiac myxoma is the most common benign cardiac tumour. Atrial myxoma most commonly arises from the left atrium and, less frequently, from the right atrium or both ventricles. Cardiac myxoma arising from the tricuspid valve is rare. These tumours can present with right heart failure as a result of right ventricular outflow tract obstruction. A high index of suspicion and appropriate investigations are necessary for making the correct diagnosis. Fatal complications such as embolisation and obstruction of the outflow tract and other intracardiac structures make prompt surgical intervention necessary. We report on a patient with a rare type of giant myxoma arising from the tricuspid valve. He underwent successful operation with en-bloc removal of the tumour, while preserving the integrity of the tricuspid valve.

Homeless problems in Taiwan: Looking beyond legality toward social issues

Encouraged by the public policy, citizens in Taiwan have traditionally enjoyed a high percentage of home ownership. Therefore, it has been perplexing and enigmatic to witness the growing homeless population sleeping outside in public areas in recent years. Public actions have been called for to deal with the problem. However, the approach of these public actions has depended on how the problem of homelessness has been defined. This paper presents a historical context of how homelessness has been presented in policy discourses. Further, on the basis of a survey conducted in 2004, this paper describes the profile of the homeless and discusses why the homeless began sleeping on the streets. Finally, an outreach worker narrates his story about working with the homeless in Taipei City, the capital of Taiwan. The paper also includes policy implications in terms of appropriate public actions to be taken in response to the homelessness problem in Taiwan.

Pulmonary valve replacement after surgical repair of tetralogy of Fallot

OBJECTIVE

To evaluate the results of pulmonary valve replacement in patients with severe pulmonary regurgitation after tetralogy of Fallot repair in Hong Kong.

DESIGN

Retrospective review.

SETTING

University teaching hospital, Hong Kong.

PATIENTS

Consecutive patients undergoing pulmonary valve replacement after repair of tetralogy of Fallot between August 2002 and December 2008.

MAIN OUTCOME MEASURES

Magnetic resonance imaging of right ventricular volume and cardiopulmonary exercise test data before and after the operation were documented and compared.

RESULTS

Over a 6-year period, 16 patients underwent pulmonary valve replacement for severe pulmonary regurgitation after prior complete repair for tetralogy of Fallot. There was no in-hospital mortality. The mean time interval between the initial repair and pulmonary valve replacement was 19 (standard deviation, 9) years. In three patients, the indication for pulmonary valve replacement was symptomatic severe pulmonary regurgitation, and asymptomatic progressive right ventricular dilatation in the remaining 13 patients. After pulmonary valve replacement, there was a significant decrease in the mean indexed right ventricular end-diastolic volume from 173 (standard deviation, 44) mL/m(2) to 103 (19) mL/m(2) (P=0.043). After the operation, there was also a tendency for improvement of the right ventricular ejection fraction and the maximum oxygen consumption: from 42% (standard deviation, 9%) to 47% (6%) [P=0.173], and 27 (4) mL/kg/min to 29 (4) mL/kg/min (P=0.208), respectively.

CONCLUSION

Pulmonary valve replacement for severe pulmonary regurgitation after tetralogy of Fallot repair is a safe procedure. However, the indications for such an operation in asymptomatic patients remain controversial. Further studies are required to better delineate the timing of pulmonary valve replacement in this patient group.

Isolated left ventricular non-compaction: an unusual indication for heart transplantation

We report a patient with isolated left ventricular non-compaction diagnosed by echocardiography and cardiac magnetic resonance imaging. She developed refractory congestive heart failure and subsequently underwent successful heart transplantation. This type of cardiomyopathy is thought to be caused by the arrest of normal embryogenesis of the endocardium and myocardium. The spectrum of clinical, radiological, and pathological abnormalities is discussed.

Primary cardiac angiosarcoma of left atrium

Cardiac angiosarcoma usually arises from the right atrium. We report an extremely rare case of primary angiosarcoma originating from the left atrium in a 70-year-old woman. This represents the ninth reported case of left-sided cardiac angiosarcoma in the English literature. Analysis of all nine cases shows that this malignant neoplasm occurs more in female patients with a mean age of 60 years, unlike the right-sided one which typically affects male patients in their early 40s. The prognosis of this tumor is extremely poor with life expectancy lying between 3 to 34 months despite early diagnosis by imaging and multimodality treatment.

Impact of diabetes on early and mid-term survival after coronary artery bypass graft surgery in the Hong Kong Chinese population

OBJECTIVE

To determine the impact of diabetes on early and mid-term survival in the Hong Kong Chinese population undergoing coronary artery bypass graft surgery.

DESIGN

Prospective study.

SETTING

Regional hospital, Hong Kong.

PATIENTS

A total of 904 consecutive patients following coronary artery bypass graft surgery from November 1999 to December 2003 were prospectively analysed. Among them, 377 (42%) diabetic and 527 (58%) non-diabetic patients were evaluated.

MAIN OUTCOME MEASURES

Hospital mortality, mid-term mortality, and percutaneous coronary intervention-free survival.

RESULTS

The diabetic group had a higher risk score than the non-diabetic group (mean+/-standard deviation: EuroSCORE 4.7+/-3.4 and 3.6+/-3.4, respectively; P<0.001). Hospital mortality was 3.4% in the diabetic group compared to 2.8% in the non-diabetic group (P=0.698). Multiple logistic regression analysis identified left ventricular ejection fraction of less than 30% and preoperative intubation as independent risk factors for early hospital death. There were 81 late deaths and the actuarial survival at 48 months for the diabetic and non-diabetic patients were 86% and 90%, respectively (P=0.298). The angina-free survival and percutaneous coronary intervention-free survival at 48 months for the diabetic and non-diabetic patients yielded no statistically significant difference.

CONCLUSIONS

Diabetes mellitus was not a predictor of early and mid-term mortality after coronary artery bypass graft surgery in our Chinese population. Furthermore, diabetes did not affect angina recurrence or intervention free-survival up to 4 years.

Mortality prediction in adult cardiac surgery patients: comparison of two risk stratification models

OBJECTIVE

To assess and compare the two commonly applied models--EuroSCORE and Parsonnet--in our local adult cardiac surgery patients, according to risk factor quantification related to mortality using a risk stratification protocol to assess the quality of cardiac surgical care.

DESIGN

Prospective study.

SETTING

Cardiac surgery centre in a regional hospital in Hong Kong.

PATIENTS

All adult patients undergoing coronary artery bypass graft and heart valve surgery at the Grantham Hospital were evaluated prospectively from November 1999 to July 2005.

MAIN OUTCOME MEASURES

In-hospital mortality was the defined end-point. Statistical analyses consisted of observed against expected mortality, Hosmer-Lemeshow goodness-of-fit test for calibration accuracy, and receiver operating characteristic curve for discrimination performance.

RESULTS

During the study period, 1247 patients underwent coronary artery bypass graft surgery and 1406 underwent heart valve surgery. Observed mortality rates in these two patient groups were 2.9% and 4.8% respectively. The expected mortality rates as predicted by the EuroSCORE were (mean+/-standard deviation) 4.0+/-3.3% and 5.2+/-3.0% respectively, and by the Parsonnet model were 5.9+/-4.2% and 7.3+/-4.4% respectively. EuroSCORE performed better than the Parsonnet model at predicting in-hospital mortality assessed by the Hosmer-Lemeshow goodness-of-fit test. The areas under the receiver operating characteristic curves in coronary artery bypass graft surgery were 0.76 for EuroSCORE and 0.74 for Parsonnet. The receiver operating characteristic curve areas in valve surgery were 0.77 for EuroSCORE and 0.79 for Parsonnet.

CONCLUSION

Despite significant geographic and demographic differences between European and Asian patients, in our local adult cardiac surgery patients, the EuroSCORE performed well with good calibration and discrimination in predicting mortality. There was a tendency for both models to over predict. However, the EuroSCORE can serve as a baseline for the development of a local risk model.

Using position, fonts and cited references to retrieve scientific documents

As more and more documents become available on the internet, finding documents that fit users' needs from databases containing millions of documents is becoming increasingly important. Since a scientific document is a structured text, it has some useful features that can be used to improve retrieval performance. In this work, we investigate three such features: fonts, position and cited references. While past research has used these three features individually to improve document searching, no existing research discusses how to integrate these three together to improve retrieval performance. This work first investigates the relationships among them, and then uses these three features to design a novel retrieval method based on the discovered relationships. Extensive experiments have been carried out with real scientific documents to show its effectiveness. Our empirical results show that using the location factor alone achieves the same performance as considering location and font factors simultaneously. We also observed that citation similarity is useful only when the similarity is high. Based on these two clues, we developed a method to combine the content vector and reference vector conditionally, and as a result, this integrated approach does, indeed, improve search performance.

Foreign body-induced aorto-oesophageal fistula: a review of five cases and their management

Foreign body-induced aorto-oesophageal fistula is a rare cause of massive upper gastro-intestinal bleeding and, in the absence of a timely diagnosis and surgical intervention, can be fatal. During a period of 25 years, five patients with foreign body-induced aorto-oesophageal fistula underwent surgery in our department. Three patients survived. All survivors required more than one surgical intervention. The clinical course of these five patients and the management of this potentially fatal condition are reviewed.

Long-term anticoagulation therapy and thromboembolic complications after the Fontan procedure

BACKGROUND

The necessity for chronic anticoagulation of Fontan patients remains controversial. We determined the prevalence of thromboembolic complications after the Fontan procedure in relation to different long-term anticoagulation strategies.

METHODS

The clinical outcomes, postoperative anticoagulation strategies and occurrence of thromboembolic complications in 102 ethnic Chinese patients who had undergone Fontan procedure between 1980 and 2002 were reviewed.

RESULTS

The early and late surgical mortalities, all unrelated to thromboembolism, were 10.8% (11/102) and 5.8% (6/104), respectively. Of the 85 survivors, 46 (54%) were maintained on long-term warfarin therapy, 8 (9%) on aspirin prophylaxis while 31 (37%) were not on chronic anticoagulation. Four (4.5%) patients, two with and two without warfarin prophylaxis, developed thromboembolic complications at 0.14 to 7.7 years after the Fontan procedure (0.74%/patient-year). Three had a grossly dilated right atrium after atriopulmonary connection, two of whom had atrial fenestrations. The other had atrial tachycardia. Freedom from development of thromboembolic complications (mean+/-S.E.) at 1, 5 and 10 years after surgery was 97+/-19%, 96+/-2.5% and 92+/-4.2%, respectively. When compared with those on long-term warfarin therapy, patients without chronic anticoagulation were followed-up longer (p=0.001), more likely to have undergone atriopulmonary connection (p<0.001), less likely to have fenestrations (p=0.02) and cardiac arrhythmias (p=0.02) but not predisposed to increased risk of thromboembolism (p=1.00).

CONCLUSION

The study supports the contention that chronic anticoagulation may not be required for majority of ethnic Chinese Fontan patients. Nonetheless, it may perhaps be considered in those with grossly dilated right atrium, cardiac arrhythmias and residual right-to-left shunts.

Gender difference in self-esteem of Hong Kong Chinese with cardiac diseases

Self-esteem is an indicator of a person's subjective quality of life due to its close relationship to a person's behavioural competence, positive self-experience, and sense of self-actualization. The present study aimed to investigate the basis of self-esteem in people with cardiac diseases, according to gender, after their cardiac surgery. The findings showed that there were prominent gender differences in the subjects' self-esteem. Women (aged<60) showed statistically significant higher ratings in the importance of 11 life events importance and the satisfaction of three life events than men. The study also found cultural uniqueness: Hong Kong Chinese (both men and women) with cardiac diseases generally indicated that social (interpersonal) self-concept dimensions were more important than achievement (personal) self-concept dimensions in their life perception. These findings are noteworthy for setting optimum goals of rehabilitation apart from return to work.

Differential influences of various arsenic compounds on glutathione redox status and antioxidative enzymes in porcine endothelial cells

The cellular response and detoxification mechanisms in porcine endothelial cells (PAECs) to arsenic trioxide (As2O3), sodium arsenite (NaAsO2) and sodium arsenate (Na2HAsO4) were investigated. NaAsO2 at 20 microM for 72 h increased Cu/Zn superoxide dismutase activity resulting in elevated intracellular hydrogen peroxide levels, but As2O3 and Na2HAsO4 did not. Trivalent arsenic compounds increased intracellular oxidized glutathione (GSSG) and total glutathione (GSH) and cellular glutathione peroxidase (cGPX) and glutathione S-transferase (GST) activity, but not glutathione reductase activity. The increased cGPX activity resulted in an elevated cellular GSSG content. Na2HAsO4 increased the cellular GSSG level at 72 h compared to controls. These results imply that the increased GSH content responding to the oxidative stress by trivalent arsenic compounds may be mainly related to the regulation of GSH turnover. The increased GST activity implies that the elevated intracellular GSH level responding to the oxidative stress may be used to conjugate arsenic in PAECs and facilitate arsenic efflux.

C. elegans CED-12 acts in the conserved crkII/DOCK180/Rac pathway to control cell migration and cell corpse engulfment

We have identified and characterized a novel C. elegans gene, ced-12, that functions in the conserved GTPase signaling pathway mediated by CED-2/Crkll, CED-5/DOCK180, and CED-10/Rac to control cell migration and phagocytosis of apoptotic cells. We provide evidence that ced-12 likely acts upstream of ced-10 during cell migration and phagocytosis and that CED-12 physically interacts with CED-5 and forms a ternary complex with CED-2 in vitro. We propose that the formation and localization of a CED-2-CED-5-CED-12 ternary complex to the plasma membrane activates CED-10, leading to the cytoskeletal reorganization that occurs in the polarized extension of cell surfaces in engulfing cells and migrating cells. We suggest that CED-12 counterparts in higher organisms regulate cytoskeleton dynamics, as CED-12 does in C. elegans.

Severe mitral regurgitation due to mitral valve prolapse associated with Bland-White-Garland syndrome

Bland-White-Garland syndrome refers to the rare congenital cardiac abnormality whereby the left coronary artery arises from the pulmonary artery. The natural history of this condition is highly variable, ranging from death in early infancy to asymptomatic adult survival. It is sometimes diagnosed in adults with mitral regurgitation thought to be of ischaemic origin. We report a case of a 29-year-old man with Bland-White-Garland syndrome and concomitant mitral valve prolapse, and review the literature on the appropriate investigations and management of this abnormality. Recognition and diagnosis of this condition is important because of the potentially life-threatening complications, which may be prevented by surgical intervention.

Triploid pregnancy after ICSI of frozen testicular spermatozoa into cryopreserved human oocytes: case report

Although freezing oocytes is ethically more acceptable than cryopreservation of embryos, variable oocyte survival, fertilization rate and possible risk of increased ploidy after cryopreservation have precluded the widespread clinical application of oocyte cryopreservation in assisted reproduction techniques. We report a triploid pregnancy from intracytoplasmic sperm injection of recombinant FSH-stimulated frozen/thawed testicular spermatozoa into cryopreserved oocytes in a hormone replacement cycle. To our knowledge, this is the first report of a pregnancy where both gametes have been frozen. It illustrates the need for further research when applying new techniques in assisted reproduction.

A rare complication of PTCS: ruptured balloon with retained broken catheter

This report describes a rare situation in which a retained ruptured balloon with broken catheter was caught in an incompletely opened stent during a percutaneous transluminal coronary stenting (PTCS) procedure in a 84 year old gentleman. A short, warm heart bypass and single cross clamping coronary artery bypass grafting procedure was performed.

The ultrasound diagnosis of retained fetal bones in West African patients complaining of infertility

Prolonged retention of intrauterine bone is a recognised cause of secondary infertility. Between 1989 and 1995, eleven West African women had retained intrauterine bone as the cause of their infertility. All the women had had termination of pregnancies in their countries of origin. Transvaginal ultrasound scan detected bright intrauterine echoes suggestive of bone which was confirmed and removed at hysteroscopy. Subsequently eight women conceived spontaneously 12 pregnancies. Doctors treating West African women with infertility should be aware of this condition and include transvaginal ultrasound scan in their investigations.

Left ventricular rupture after mitral valve replacement

BACKGROUND

What are the immediate and long term outcomes of patients who had rupture of the left ventricle after mitral valve replacement?

METHODS

EXPERIMENTAL DESIGN

A retrospective study with a 20-year follow-up.

SETTING

Experience in a single tertiary referral cardiothoracic surgery hospital.

PARTICIPANTS

20 out of 3105 patients that received mitral valve replacement.

INTERVENTION

All these 20 patients received re-exploration for a trial of repair of left ventricular rupture either by an internal or an external or a combined repair.

MEASURES

Operative mortality and long term outcome of the survivals.

RESULTS

Most patients (16.80%) were female and had rheumatic mitral valve disease. The mean age of the patients was 58.1 years. All patients underwent attempted repair, usually by removal of the prosthesis and reconstitution of the ventricle from within the left atrium (75%). Thirteen (65%) patients died. Two late deaths were of unrelated cause. One surviving patient developed a late ventricular false aneurysm but did not undergo repeat surgery. One patient developed severe mitral regurgitation due to tissue failure of the bioprosthesis 12 years after surgery and she underwent a successful reoperation.

CONCLUSIONS

We believe that all patients should be placed back on cardiopulmonary bypass for an internal repair. The long term outcome of the survivals is satisfactory.

Identification and Expression Pattern of DNA Polymerase alpha Gene in a Marine Diatom, Skeletonema costatum

: To investigate the potential of DNA polymerase alpha as a marker for DNA replication in phytoplankton, two gene fragments that showed a high degree of similarity with eukaryotic DNA polymerase alpha were cloned from two strains of a diatom, Skeletonema costatum (Greville) Cleve. The gene fragments amplified with the polymerase chain reaction were 397 and 396 bp in length, respectively. The deduced amino acid sequences showed 44% to 61% similarity to the corresponding regions of DNA polymerase alpha sequences of eukaryotic organisms ranging from yeast to humans. The similarity was especially high in three evolutionarily conserved regions within the amplified fragments. Further, hybridization patterns from Southern blotting confirmed that the amplified fragments were an integral part on the genome of S. costatum. In batch cultures abundant messenger of DNA polymerase alpha appeared in the late exponential phase and the early stationary phase. This pattern suggests that DNA polymerase alpha expression is associated with actively dividing cells.

Surgical resection of pulmonary metastases

BACKGROUND

To review the results of complete surgical resection of pulmonary metastasis -- a ten-year experience.

SETTING

Retrospective analysis of all patients with lung secondaries who received complete surgical resection of pulmonary metastases (from 1984 to 1995) in Grantham Hospital, Hong Kong. Sixty patients over a 10-year period were studied.

METHODS

Eighty thoracotomies were performed with 88 tumour nodules excised. The follow-up period ranged from 5 months to 111 months.

RESULTS

Thirteen (14.8%) specimens were found to have tumour size greater than 5.0 cm. This may reflect late detection of metastatic tumour and probably accounts for the higher percentage of our patients receiving more major lung resections (63.3%) than just wedge resections (36.6%). The mean survival period for the subgroup with hepatocellular carcinoma was 28.2 months and for the nasopharyngeal carcinoma group was 25 months. The mean survival of the whole group was 26.4 months.

CONCLUSIONS

The favourable outcome for hepatocellular carcinoma and nasopharyngeal carcinoma could be due to the result of selection of patients with more favourable prognosis for surgery. The latent period, using 12 months as a break-off point, did not affect patient survival in our study.