DNA Carrier-Assisted Molecular Ping-Pong in an Asymmetric Nanopore.

Nanopore analysis relies on ensemble averaging of translocation signals obtained from numerous molecules, requiring a relatively high sample concentration and a long turnaround time from the sample to results. The recapture and subsequent re-reading of the same molecule is a promising alternative that enriches the signal information from a single molecule. Here, we describe how an asymmetric nanopore improves molecular ping-pong by promoting the recapture of the molecule in the trans reservoir. We also demonstrate that the molecular recapture could be improved by linking the target molecule to a long DNA carrier to reduce the diffusion, thereby achieving over 100 recapture events. Using this ping-pong methodology, we demonstrate its use in accurately resolving nanostructure motifs along a DNA scaffold through repeated detection. Our method offers novel insights into the control of DNA polymer dynamics within nanopore confinement and opens avenues for the development of a high-fidelity DNA detection platform.

Intravascular lithotripsy to treat an underexpanded coronary stent: 4-Month angiographic and OCT follow-up.

We report the case of a 79-year-old man with stable angina who underwent percutaneous coronary intervention to a severe and calcified left circumflex lesion. Despite extensive preparation of the lesion with high-pressure balloon predilatation and rotablation, the implanted stent was grossly underexpanded and failed to respond to high-pressure balloon postdilatation. The patient was readmitted 6 weeks later for intravascular lithotripsy that resulted in excellent stent expansion. Coronary angiography with optical coherence tomography 4 months later revealed sustained acute lumen gain with no evidence of stent recoil or in-stent restenosis.

Acute arterial cardiovascular events risk in patients with primary membranous nephropathy.

BACKGROUND: Venous thromboembolism is a well established risk in patients with primary membranous nephropathy (MN) due to deficiency in natural anti-coagulants. Recent studies suggested a higher risk of arterial thrombotic events as well in this group. AIM: To identify that risk in our cohort. METHODS: We reviewed the data of all patients who had biopsy proven primary MN at our institute between 2003 and 2013. Clinical data were retrospectively reviewed until November 2016. The cardiovascular (CV) events, including acute coronary syndromes and strokes were determined and included only if occurred after the diagnosis of the nephropathy. RESULTS: A total of 204 patients had biopsy proven MN. Follow up information was available for 166 patients. Thirty-one patients (18.6%) developed CV events during follow up. Thirty-eight per cent of total events occurred within 1 year of MN diagnosis. Forty-two per cent of those who developed CV events were not on anti-thrombotic medications and 60% were not on statin therapy. Male gender, age, diabetes and absence of statins therapy were associated with higher rates of CV events in this group. CONCLUSION: There is an increased risk of arterial events in patients with primary MN. This risk is greatest in the first year of diagnosis. The risk should be highlighted in this group of patients and anti-platelets and statin therapy should be considered especially during the initial phase of the disease.

A review of a regional primary percutaneous coronary intervention service, with a focus on door to reperfusion times: the 2012 Auckland/Northland experience.

AIMS: Primary percutaneous coronary intervention (PCI) is the optimal management for ST segment elevation myocardial infarction (STEMI) patients. We reviewed the largest primary PCI regional service in New Zealand: the Auckland/Northland service based at Auckland City Hospital, to assess patient management, in particular the door to reperfusion times (DTRTs), and predictors of death in hospital. METHODS: We obtained patient details from a comprehensive prospective database of all primary PCI patients admitted with STEMI from 1/1/12 to 31/12/12 to the Auckland City Hospital cardiac catheterisation laboratory. Of four District Health Boards (DHBs) within the region, two accessed this regional service at all times, and two accessed the Auckland City Hospital cardiac catheterisation laboratory 'after hours': all times except for 08:00 to 16:00 hours on Monday to Friday. RESULTS: A total of 401 adult patients underwent a primary PCI at the Auckland City Hospital Regional centre for a STEMI presentation, over the 12 months period. The median patient age was 61 years, 77% were male. Overall 183 (46%) (95% CI 41, 51) patients achieved a DTRT of < 90 mins, and 266 (66%) (95% CI 61, 71) a DTRT of < 120 mins, with a clear geographical influence to these times. Of 27 patients with direct transfer to the catheter laboratory from the community, the DTRT was < 120 mins in 24 (92%) (95% CI 72, 96) patients. In-hospital mortality was 24 (6%) patients (95% CI 4, 9). CONCLUSIONS: The 2012 Auckland/Northland primary PCI service delivers good outcomes consistent with current Australasian standards. Although geographical isolation complicates door to reperfusion times, these may potentially be improved by more focus on direct transfer to the cardiac catheterisation laboratory, especially directly from the community.

Simultaneous identification of viruses and viral variants with programmable DNA nanobait.

Respiratory infections are the major cause of death from infectious disease worldwide. Multiplexed diagnostic approaches are essential as many respiratory viruses have indistinguishable symptoms. We created self-assembled DNA nanobait that can simultaneously identify multiple short RNA targets. The nanobait approach relies on specific target selection via toehold-mediated strand displacement and rapid readout via nanopore sensing. Here we show that this platform can concurrently identify several common respiratory viruses, detecting a panel of short targets of viral nucleic acids from multiple viruses. Our nanobait can be easily reprogrammed to discriminate viral variants with single-nucleotide resolution, as we demonstrated for several key SARS-CoV-2 variants. Last, we show that the nanobait discriminates between samples extracted from oropharyngeal swabs from negative- and positive-SARS-CoV-2 patients without preamplification. Our system allows for the multiplexed identification of native RNA molecules, providing a new scalable approach for the diagnostics of multiple respiratory viruses in a single assay.

Lifetime of glass nanopores in a PDMS chip for single-molecule sensing.

Nanopore sensing is an emerging technology that has many biosensing applications ranging from DNA sequencing using biological pores to biomolecular analysis using solid-state pores. Solid-state nanopores that are more stable are an attractive choice for biosensing applications. Still, biomolecule interactions with the nanopore surface reduce nanopore stability and increase usage costs. In this study, we investigated the biosensing capability for 102 quartz glass nanopores with a diameter of 11-18 nm that were fabricated using laser-assisted capillary pulling. Nanopores were assembled into multiple microfluidic chips that were repeatedly used for up to 19 weeks. We find that using vacuum storage combined with minimal washing steps improved the number of use cycles for nanopores. The single-molecule biosensing capability over repeated use cycles was demonstrated by quantitative analysis of a DNA carrier designed for detection of short single-stranded DNA oligonucleotides.

Outcomes of patients with ST elevation myocardial infarction in the era of second-generation drug eluting stents; five-year follow-up.

AIM: The second-generation everolimus and zotarolimus drug eluting stents (DES) have shown superiority for repeat revascularisation and safety to the first-generation devices for stable patients. However, the benefit of those devices in the setting of ST elevation myocardial infarction (STEMI) has remained questionable due to concern regarding stent thrombosis (ST) seen with the first-generation devices. We review the outcomes of patients with STEMI treated in our centre at a time when the second-generation DES became the standard of care. METHODS: All patients who presented to our institution with STEMI and underwent emergency percutaneous intervention (PCI) in 2012 with second-generation DES were identified. Case notes and electronic records were reviewed. Patients undergoing staged PCI to non-culprit lesions were excluded. Patients who died during the primary cardiac event with cardiogenic shock were also excluded. RESULTS: A total of 399 patients (mean age 65+/-12, 274 (76%) male) were identified. Thirty-five patients (8.7%) died during hospitalisation with cardiogenic shock and were excluded from the subsequent analysis. A further 35 patients died during follow-up. Patients received a mean of 1.15 DES. Median follow-up time was 4.7 years. Median door to reperfusion time was 90 minutes. The all-cause mortality rate for STEMI survivors was 9.6%. Cardiac mortality rate was 3.6%. Thirty-one patients (8.5%) re-presented with symptoms leading to repeat coronary angiography. In-stent restenosis (ISR) was observed only in eight patients (2.2%). The significant factors associated with re-presentation were smoking and medication non-compliance. CONCLUSION: Early mortality rates following emergency PCI for STEMI remain high despite low reperfusion times. The five-year follow-up data would suggest that STEMI survivors have good outcomes with the second-generation DES.

Impact of Using a 3D Visual Metaphor Serious Game to Teach History-Taking Content to Medical Students: Longitudinal Mixed Methods Pilot Study.

BACKGROUND: History taking is a key component of clinical practice; however, this skill is often poorly performed by students and doctors. OBJECTIVE: The study aimed to determine whether Metaphoria, a 3D serious game (SG), is superior to another electronic medium (PDF text file) in learning the history-taking content of a single organ system (cardiac). METHODS: In 2015, a longitudinal mixed methods (quantitative and qualitative) pilot study was conducted over multiple sampling time points (10 weeks) on a group of undergraduate medical students at The University of Auckland Medical School, New Zealand. Assessors involved in the study were blinded to group allocation. From an initial sample of 83, a total of 46 medical students were recruited. Participants were assigned to either a PDF group (n=19) or a game group (n=27). In total, 1 participant left the PDF group after allocation was revealed and was excluded. A total of 24 students in the game group and 14 students in the PDF group completed follow-up 7 weeks later. Using an iterative design process for over a year, with input from a variety of clinical disciplines, a cardiac history-taking game and PDF file were designed and informed by Cognitive Load Theory. Each group completed its intervention in 40 min. A total of 3 levels of Kirkpatrick training evaluation model were examined using validated questionnaires: affective (perception and satisfaction), cognitive (knowledge gains and cognitive load), and behavioral attitudes (Objective Structured Clinical Exam) as well as qualitative assessment. A priori hypotheses were formulated before data collection. RESULTS: Compared with baseline, both groups showed significant improvement in knowledge and self-efficacy longitudinally (P<.001). Apart from the game group having a statistically significant difference in terms of satisfaction (P<.001), there were no significant differences between groups in knowledge gain, self-efficacy, cognitive load, ease of use, acceptability, or objective structured clinical examination scores. However, qualitative findings indicated that the game was more engaging and enjoyable, and it served as a visual aid compared with the PDF file. CONCLUSIONS: Students favored learning through utilization of an SG with regard to cardiac history taking. This may be relevant to other areas of medicine, and this highlights the importance of innovative methods of teaching the next generation of medical students.

Atrial fibrillation after cardiac surgery: Prevention and management: The Australasian experience.

BACKGROUND: Atrial fibrillation (AF) after cardiac surgery is a major health problem that is associated with a significant financial burden. This paper aims to highlight this problem and review the current guidelines in the prevention and management of AF after cardiac surgery, providing our experience in the Australasian centers. METHODS: We conducted a literature review using mainly PubMed to compare the current practice with the available evidence. EMBASE and Cochrane library were also searched. We concurrently developed an online questionnaire to collect data from other Australasian centers regarding their approach to this problem. RESULTS: We identified 194 studies that were considered relevant to our research. We did not find any formal protocols published in the literature. From our Australasian experience; seven centers (58%) had a protocol for AF prophylaxis. The protocols included electrolytes replacement, use of amiodarone and/or ß-blockers. Other strategies were occasionally used but were not part of a structured protocol. CONCLUSION: The development of an integrated medical and surgical protocol for the prophylaxis of AF after cardiac surgery is an important aspect for the care of postoperative cardiac patients. Considerations of prophylactic strategies other than those routinely used should be included in the protocol. This area should receive considerable attention in order to reduce the postoperative complications and health costs.

A systematic review of clozapine-induced myocarditis.

BACKGROUND: Clozapine is an atypical antipsychotic that is beneficial to some patients who failed to have an adequate clinical response to other antipsychotic drugs. Its clinical use is limited due to several potentially fatal adverse reactions including myocarditis. Careful monitoring of patients on clozapine is required. METHODS: We conducted a systematic review of the literature on myocarditis associated with clozapine therapy. The search engines used to identify cases were MEDLINE, EMBASE, PsycINFO and Cochrane reviews. The references included in the manuscripts reviewed were searched to identify additional reports. RESULTS: We identified a total of 3347 articles that addressed the cardiac complications of clozapine. Of these, 82 articles detailed cases of clozapine-induced myocarditis. The median age of patients and dose of clozapine at presentation was 30years and 250mg/day respectively. Symptoms and signs of myocarditis developed in 87% of patients within the first month of treatment. Clinical presentation included: shortness of breath (67%), fever (67%) and tachycardia (58%). Cardiac markers were elevated in 87% of the 54 cases that reported these markers. Global ventricular dysfunction was the predominant echocardiogram finding (57%). CONCLUSIONS: Patients on clozapine require routine monitoring for symptoms and signs of myocarditis during the first three months of therapy. This adverse drug reaction is difficult to diagnose due the non-specific nature of the symptoms and signs. Alternate causes of myocarditis should be ruled out before attributing the myocarditis to clozapine.

Paravalvular leak after mechanical aortic valve replacement causing hemolytic anemia: closure with vascular plug.

: We report a case of a 79-year-old man with hemolytic anemia caused by a small paravalvular leak after aortic valve replacement with mechanical prosthesis. The defect was successfully treated with a vascular plug.

A systematic review of clozapine induced cardiomyopathy.

BACKGROUND: Clozapine is a unique anti-psychotic medication that is most effective in the treatment of refractory schizophrenia and reducing suicidality. Cardiomyopathy is among the side effects of this medication that limits its use. There are a number of case reports, case series and expert opinion papers discussing clozapine induced cardiomyopathy, but there is no evidence-based review of the subject to guide clinicians. METHODS: We undertook a systematic review of the literature on cardiomyopathy associated with clozapine. The primary systemic search was in MEDLINE but EMBASE, PsycINFO, and Cochrane were searched and manufacturers of clozapine were contacted for cases. Articles were then individually reviewed to find additional reports. RESULTS: We identified 17 articles detailing 26 individual cases and 11 additional articles without individual case data. The mean age at time of diagnosis was 33.5 years. The mean dose of clozapine on presentation was 360 mg. Symptoms developed at an average of 14.4 months after initiating clozapine. The clinical presentation was generally consistent with heart failure: including shortness of breath (60%) and palpitations (36%). Echocardiography at presentation showed dilated cardiomyopathy in 39% of cases and was not specified in other cases. CONCLUSION: There should be a low threshold in performing echocardiography in suspected cases of clozapine induced cardiomyopathy. Clozapine should be withheld in the setting of cardiomyopathy without other explanation. There is limited data on the safety of drug re-challenge in clozapine induced cardiomyopathy. Re-challenge may be considered in carefully selected cases but close monitoring and frequent echocardiography are required.