Fibroblast mediated dynamics in diffusively uncoupled myocytes: a simulation study using 2-cell motifs

In healthy hearts myocytes are typically coupled to nearest neighbours through gap junctions. Under pathological conditions such as fibrosis, or in scar tissue, or across ablation lines myocytes can uncouple from their neighbours. Electrical conduction may still occur via fibroblasts that not only couple proximal myocytes but can also couple otherwise unconnected regions. We hypothesise that such coupling can alter conduction between myocytes via introduction of delays or by initiation of premature stimuli that can potentially result in reentry or conduction blocks. To test this hypothesis we have developed several 2-cell motifs and investigated the effect of fibroblast mediated electrical coupling between uncoupled myocytes. We have identified various regimes of myocyte behaviour that depend on the strength of gap-junctional conductance, connection topology, and parameters of the myocyte and fibroblast models. These motifs are useful in developing a mechanistic understanding of long-distance coupling on myocyte dynamics and enable the characterisation of interaction between different features such as myocyte and fibroblast properties, coupling strengths and pacing period. They are computationally inexpensive and allow for incorporation of spatial effects such as conduction velocity. They provide a framework for constructing scar tissue boundaries and enable linking of cellular level interactions with scar induced arrhythmia.

Regional tissue oxygenation in asymptomatic neonates at high risk for neonatal abstinence syndrome and impact of non-pharmacologic interventions: A case report

BACKGROUND

Improving neonatal abstinence syndrome (NAS) management is an important concern, and objective measures of its physiologic impact remain elusive. We sought to determine whether near-infrared spectroscopy (NIRS)-derived tissue oxygenation (rSO2) and fractional tissue oxygen extraction (FTOE) demonstrated physiologically plausible changes correlating with standard NAS scoring.

METHODS

Thirty subjects (mean 39 weeks' GA and 3 127 g BW) underwent cerebral and peripheral muscle NIRS monitoring on Days of Life (DOL) Three, Five, and Seven. We examined correlations between NAS scores and FTOE and assessed the impact of non-pharmacologic swaddling and cuddling.

RESULTS

No statistically significant correlations between NAS scores and FTOE were observed; however, plausible trends were demonstrated between NAS scores and cerebral measurements. Buprenorphine-exposed babies (57%) showed significantly lower FTOE when swaddled (DOL7).

CONCLUSIONS

Tissue oxygenation monitoring demonstrates potential to provide objective, clinically relevant physiologic information on infants at risk for NAS. Further study is required to determine whether NIRS-derived measures could assist in individualizing NAS care.

Feasibility of a pregnancy intervention mimicking viral transmission mitigation measures on the incidence of preterm birth in high-risk pregnant women enrolled in antenatal clinics in Melbourne, Australia: protocol for a pilot, randomised trial

INTRODUCTION

Preterm birth is a leading cause of perinatal morbidity and mortality. During the COVID-19 pandemic, reduction in rates of preterm birth in women exposed to viral mitigation measures was reported by multiple studies. In addition, others and we observed a more pronounced reduction of preterm birth in women who had previously experienced a preterm birth. The aim of this pilot study is to establish the feasibility of a lifestyle intervention based on viral mitigation measures in high-risk pregnancies, with the ultimate aim to reduce the incidence of preterm birth.

METHODS AND ANALYSIS

One hundred pregnant women, enrolled in antenatal clinics at two tertiary maternity centres in Melbourne, Australia, who have had a previous preterm birth between 22 and 34 weeks gestation will be recruited. This is a two-arm, parallel group, open-label randomised controlled feasibility trial: 50 women will be randomised to the intervention group, where they will be requested to comply with a set of lifestyle changes (similar to the viral mitigation measures observed during the pandemic). Another 50 women will be randomised to the control group, where they will undergo standard pregnancy care. The primary outcome of this trial is feasibility, which will be assessed by measuring patient eligibility rate, recruitment rate, compliance rate and data completion rate. Secondary outcomes include incidence of preterm birth, maternal satisfaction, maternal quality of life and other pregnancy outcomes. Standard methods in statistical analysis for randomised controlled trials on an intention to treat basis will be followed.

ETHICS AND DISSEMINATION

This trial has been approved by the Monash Human Research Ethics Committee; approval reference number RES-22-0000-122A. Study findings will be reported and submitted to peer-reviewed journals for publication, and presentation at conferences.

TRIAL REGISTRATION NUMBER

ACTRN12622000753752; Pre-results.

Circulating tumor DNA association with residual cancer burden after neoadjuvant chemotherapy in triple-negative breast cancer in TBCRC 030

BACKGROUND

We aimed to examine circulating tumor DNA (ctDNA) and its association with residual cancer burden (RCB) using an ultrasensitive assay in patients with triple-negative breast cancer (TNBC) receiving neoadjuvant chemotherapy.

PATIENTS AND METHODS

We identified responders (RCB 0/1) and matched non-responders (RCB 2/3) from the phase II TBCRC 030 prospective study of neoadjuvant paclitaxel versus cisplatin in TNBC. We collected plasma samples at baseline, 3 weeks and 12 weeks (end of therapy). We created personalized ctDNA assays utilizing MAESTRO mutation enrichment sequencing. We explored associations between ctDNA and RCB status and disease recurrence.

RESULTS

Of 139 patients, 68 had complete samples and no additional neoadjuvant chemotherapy. Twenty-two were responders and 19 of those had sufficient tissue for whole-genome sequencing. We identified an additional 19 non-responders for a matched case-control analysis of 38 patients using a MAESTRO ctDNA assay tracking 319-1000 variants (median 1000 variants) to 114 plasma samples from 3 timepoints. Overall, ctDNA positivity was 100% at baseline, 79% at week 3 and 55% at week 12. Median tumor fraction (TFx) was 3.7 × 10-4 (range 7.9 × 10-7-4.9 × 10-1). TFx decreased 285-fold from baseline to week 3 in responders and 24-fold in non-responders. Week 12 ctDNA clearance correlated with RCB: clearance was observed in 10 of 11 patients with RCB 0, 3 of 8 with RCB 1, 4 of 15 with RCB 2 and 0 of 4 with RCB 3. Among six patients with known recurrence, five had persistent ctDNA at week 12.

CONCLUSIONS

Neoadjuvant chemotherapy for TNBC reduced ctDNA TFx by 285-fold in responders and 24-fold in non-responders. In 58% (22/38) of patients, ctDNA TFx dropped below the detection level of a commercially available test, emphasizing the need for sensitive tests. Additional studies will determine whether ctDNA-guided approaches can improve outcomes.

Behavioral shift of generation X towards OTT during Covid’19 in India

Over-the-top (OTT) services such as Netflix, Prime Video, Disney+ Hotstar, Zee5, etc., have changed consumers’ content consumption behavior. Globalization and Digitalization have encouraged consumers to have limitless access to the Internet for information, leisure, entertainment, and social interconnectedness. The increase in the availability of high-speed Internet, the latest smartphones, and breakthroughs in technology have created great opportunities for the OTT sector, with people preferring to consume content on-the-go digitally rather than traditional media services, such as cable television. The Covid’19 pandemic has seen an increase in viewership’s and subscriptions towards these streaming platforms, with people of different age groups adapting to changing viewership trends. This study aims to understand Generation X’s behavioral shift (Age 41 to 55) towards OTT during Covid’19 in India. The literature review talks about the Generation X cohort of consumers, their behavioral habits, and attitudes towards technology. It also discusses the changing trends of online content consumption and how Covid’19 has created a spark in viewership’s towards India’s online media services. The research study aims to perform explanatory research to establish a relationship between the increase in consumption and subscriptions of OTT services in India by Generation X and the impact of Covid’19 on the same. Data will be collected from consumer’s age amongst 41 to 55 in India via survey questionnaires, and linear regression tests will be performed to test the hypotheses and establish a correlation between the dependent and independent variables.

Real-world Retrospective Assessment of Initiation and Effectiveness of Dual Combination Therapy with Metformin and Teneligliptin in Drug Naïve Indian Type 2 Diabetes Mellitus Patients (INITIATE)

Introduction: Diabetes Mellitus (DM) has become the leading health concern worldwide over the last few decades. But despite advances in both understanding of the pathophysiology of Type 2 Diabetes Mellitus (T2DM), and the development of new treatment strategies, current management of patients with T2DM remains suboptimal. Initial monotherapy is frequently inadequate in patients with high baseline Glycated Haemoglobin (HbA1c). Thus, initial combination therapy has emerged as an alternative approach. Aim: To assess INItiation and effecTiveness of dual combInation therapy with metformin And Teneligliptin in drug naïvE T2DM patients (INITIATE). Materials and Methods: In this retrospective, multicentre study, newly diagnosed drug naïve T2DM patients failed with diet and exercise prior to screening and initiated with dual therapy of metformin and teneligliptin were enrolled. Data of all the patients prescribed with any therapeutic dose of metformin (250 mg, 500 mg, 750 mg, 1000 mg, 1500 mg, 2000 mg) and teneligliptin (20 mg, 40 mg) was considered. The data was analysed to assess change in glycaemic parameters from baseline to 12 weeks. Paired t-test was applied for statistical results. Results: Data of 7857 patients were analysed. The mean change of Fasting Plasma Glucose (FPG) from baseline {202.29±52.2 mg/dL (11.23±2.89 mmol/L)} to 12 weeks {142.57±34.5 mg/dL (7.91±1.91 mmol/L)} was -59.72±17.7 mg/dL (-3.31±0.98 mmol/L) (p-value <0.0001). The absolute change in mean Postprandial Plasma Glucose (PPG) from baseline {(286.26±80.43 mg/dL (15.89±4.46 mmol/L)} to 12 weeks {(198.30±42.24 mg/dL (11±2.34 mmol/L)} was -87.96±38.19 mg/dL (-4.88±2.12 mmol/L) (p-value <0.0001). Mean HbA1c level was 8.11%±1% (65±10.9 mmol/mol) at baseline and decreased significantly to 7.15%±0.94% (55±10.3 mmol/mol) (p-value <0.0001) with a mean change of -0.96±0.06 (-10.5±0.7 mmol/mol) at 12 weeks. Total 42.83% (n=3365) patients achieved target HbA1c (<7%) at 12 weeks. Conclusion: Initiation of dual therapy with metformin and teneligliptin in drug naïve Indian T2DM patients significantly improved glycaemic control.

Transpupillary collagen photocrosslinking for targeted modulation of ocular biomechanics

The central vision-threatening event in glaucoma is dysfunction and loss of retinal ganglion cells (RGCs), thought to be promoted by local tissue deformations. Here, we sought to reduce tissue deformation near the optic nerve head by selectively stiffening the peripapillary sclera, i.e. the scleral region immediately adjacent to the optic nerve head. Previous scleral stiffening studies to treat glaucoma or myopia have used either pan-scleral stiffening (not regionally selective) or regionally selective stiffening with limited access to the posterior globe. We present a method for selectively stiffening the peripapillary sclera using a transpupillary annular light beam to activate methylene blue administered by retrobulbar injection. Unlike prior approaches to photocrosslinking in the eye, this approach avoids the damaging effects of ultraviolet light by employing red light. This targeted photocrosslinking approach successfully stiffened the peripapillary sclera at 6 weeks post-treatment, as measured by whole globe inflation testing. Specifically, strain was reduced by 47% when comparing treated vs. untreated sclera within the same eye (n = 7, p=0.0064) and by 54% when comparing the peripapillary sclera of treated vs. untreated eyes (n = 7, p<0.0001). Post-treatment characterization of RGCs (optic nerve axon counts/density, and grading), retinal function (electroretinography), and retinal histology revealed that photocrosslinking was associated with some ocular toxicity. We conclude that a transpupillary photocrosslinking approach enables selective scleral stiffening targeted to the peripapillary region that may be useful in future treatments of glaucoma.

Case Reports of Two Interesting Patients with Sea Snake Envenomation

Sea Snakes have the most potent venom among snakes known to mankind and a few species are implicated in human fatalities.1 Commonest Sea snake in the Indian Sea is Enhydrina Schistosa.2 Mortality is high in spite of therapy because of multiple complications. This is a Case report of two Fishermen who were bitten by Sea Snake and developed complications.

Factors affecting stability and infectivity of SARS-CoV-2

BACKGROUND

In late 2019, a novel human coronavirus - severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) - emerged in Wuhan, China. This virus has caused a global pandemic involving more than 200 countries. SARS-CoV-2 is highly adapted to humans and readily transmits from person-to-person.

AIM

To investigate the infectivity of SARS-CoV-2 under various environmental and pH conditions. The efficacies of various laboratory virus inactivation methods and home disinfectants against SARS-CoV-2 were investigated.

METHODS

The residual virus in dried form or in solution was titrated on to Vero E6 cells on days 0, 1, 3, 5 and 7 after incubation at different temperatures. Viral viability was determined after treatment with various disinfectants and pH solutions at room temperature (20-25^oC).

FINDINGS

SARS-CoV-2 was able to retain viability for 3-5 days in dried form or 7 days in solution at room temperature. SARS-CoV-2 could be detected under a wide range of pH conditions from pH 4 to pH 11 for several days, and for 1-2 days in stool at room temperature but lost 5 logs of infectivity. A variety of commonly used disinfectants and laboratory inactivation procedures were found to reduce viral viability effectively.

CONCLUSION

This study demonstrated the stability of SARS-CoV-2 on environmental surfaces, and raises the possibility of faecal-oral transmission. Commonly used fixatives, nucleic acid extraction methods and heat inactivation were found to reduce viral infectivity significantly, which could ensure hospital and laboratory safety during the SARS-CoV-2 pandemic.

Temperature sensor based on multi-layer MoS2 coated etched fiber Bragg grating

The development of an etched fiber Bragg grating (eFBG)-based temperature sensor with a uniform multi-layer molybdenum-di-sulphide (MoS₂) coating is presented in this paper. Multi-layer MoS₂ has been coated on clad etched FBG sensors by DC magnetron sputtering of molybdenum (Mo) and subsequent sulfurization. The dependence of temperature sensitivity on the coating thickness of MoS₂ on eFBGs has been tested from room temperature to 100°C. It has been found that MoS₂ coated clad etched FBG sensors with a coating thickness of around 10 nm exhibit a maximum temperature sensitivity of ∼95  pm/°C (almost one order higher than that of bare fiber Bragg gratings), with a resolution of ∼0.01°C obtained using an FBG interrogator with 1 pm resolution.

Highly sensitive fiber Bragg grating-based pressure sensor using side-hole packaging

In this work, an analysis of pressure response of a fiber Bragg grating (FBG) sensor in a side-hole package is presented using the finite element method. Various parameters of the side-hole packaging such as hole radius, the distance of separation between them, the radius and length of the package, and the choice of the package material are considered and optimized in order to promote maximum pressure sensitivity of the FBG sensor. This investigation on optimization of the side-hole package parameters gives rise to pressure sensitivity of nearly 10⁵ times as compared with the bare FBG sensor, with the numerical values of 3 pm/MPa for a bare FBG sensor to ∼280,000  pm/MPa for an optimized side-hole package FBG sensor. Such high-pressure sensitivity of an FBG sensor is being reported for the very first time in this work, to the best of our knowledge, and can be considered as the initial step toward the realization of a highly sensitive hydrophone based on FBG for sensing underwater acoustic signals.

Discordance in latent tuberculosis (TB) test results in patients with end-stage renal disease

OBJECTIVES

This natural experiment was designed to assess the impact of exposure to an active case of tuberculosis (TB) on a group of immunosuppressed individuals, with end-stage renal disease over an extended follow-up.

STUDY DESIGN

Close contacts of people with sputum smear-positive Mycobacterium tuberculosis are at high risk of infection, particularly immunosuppressed individuals. An infectious TB healthcare worker worked in a renal dialysis unit for a month before diagnosis, with 104 renal dialysis patients, was exposed for ≥8 h.

METHODS

Patients were informed and invited for screening 8-10 weeks postexposure. They either underwent standard two-step assessment with tuberculin skin test (TST) and QuantiFERON^®-TB Gold (Cellestis GmbH; QFN) interferon-gamma release assay (IGRA) or after consent, enrolled in a study where these two tests were performed simultaneously with T-SPOT^®-TB (Oxford Immunotec Ltd; TSPOT). Patients within the study were followed up for 2 years from exposure, with QFN and TSPOT repeated at months 3 and 6 from the first testing.

RESULTS

Of 104 exposed individuals, 75 enrolled in the study. There was a high degree of discordance among QFN, TSPOT and TST. This was seen at both the first time point and also over time in subjects who were retested. No patients had active TB at the baseline testing. None received treatment for latent TB infection. Over the following 2 years, no one developed TB disease.

CONCLUSION

This study suggests that there is a low risk of progression to active TB in low-incidence countries even in high-risk groups. This plus the degree of the test result discordance emphasises the complexities of managing TB in such settings as it is unclear which of these tests, if any, provides the best diagnostic accuracy.