Heart rate during sinus rhythm predicts paroxysmal atrial fibrillation on 30-day mobile cardiac telemetry monitoring

Background

Low mean heart rate at ambulatory ECG monitoring and low resting heart rate are both predictors of later incident atrial fibrillation (AF). The aim of this study is to determine whether mean heart rate at ambulatory ECG is a predictor of paroxysmal AF that can be detected with extended ambulatory ECG registration.

Methods

We included all patients who recorded 2–30 full days of ambulatory ECG using a full disclosure mobile cardiac telemetry device in USA 2019–2020, and without AF on the first full day of registration (n=18,220, mean age 64.4 years, 57.2% women). The association between mean heart rate on the first day and the occurrence of paroxysmal AF (≥30 seconds duration) during subsequent up to 30 day ECG recording was analysed using logistic regression models adjusted for age, sex and duration of ECG recording, according to tertiles of mean heart rate (39–66, 67–76 and >77 beats per minute) as well as modelled using restricted cubic splines.

Results

During a median registration duration of 16 days there were 1,290 cases of paroxysmal AF (7.1%). More paroxysmal AF occurred in the lower tertiles of mean heart rate (11.2% in tertile 1, 6.2% in tertile 2, and 4.4% in tertile 3). After adjustment, low mean heart rate was associated with a higher risk of AF (OR 1.69, 95% CI 1.47–1.93 p<0.001 for tertile 1 vs tertile 2, and OR 1.84, 95% CI 1.58–2.15, p<0.001 for tertile 1 vs tertile 3). Cubic spline curves indicated that lowest risks of AF were seen among subjects with a mean heart rate ≈80 beats per minute.

Conclusion

Low mean heart rate at 24hECG predicts detection of paroxysmal AF during extended ≤30 day ambulatory ECG monitoring.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Swedish Heart Lung foundationSwedish Society for Medical Research

Simultaneous recording of mouse retinal ganglion cells during epiretinal or subretinal stimulation

We compared response patterns and electrical receptive fields (ERF) of retinal ganglion cells (RGCs) during epiretinal and subretinal electrical stimulation of isolated mouse retina. Retinas were stimulated with an array of 3200 independently controllable electrodes. Four response patterns were observed: a burst of activity immediately after stimulation (Type I cells, Vision Research (2008), 48, 1562-1568), delayed bursts beginning >25ms after stimulation (Type II), a combination of both (Type III), and inhibition of ongoing spike activity. Type I responses were produced more often by epiretinal than subretinal stimulation whereas delayed and inhibitory responses were evoked more frequently by subretinal stimulation. Response latencies were significantly shorter with epiretinal than subretinal stimulation. These data suggest that subretinal stimulation is more effective at activating intraretinal circuits than epiretinal stimulation. There was no significant difference in charge threshold between subretinal and epiretinal configurations. ERFs were defined by the stimulating array surface area that successfully stimulated spikes in an RGC. ERFs were complex in shape, similar to receptive fields mapped with light. ERF areas were significantly smaller with subretinal than epiretinal stimulation. This may reflect the greater distance between stimulating electrodes and RGCs in the subretinal configuration. ERFs for immediate and delayed responses mapped within the same Type III cells differed in shape and size, consistent with different sites and mechanisms for generating these two response types.

Tympanic temperature in confined beef cattle exposed to excessive heat load

Angus crossbred yearling steers (n = 168) were used to evaluate effects on performance and tympanic temperature (TT) of feeding additional potassium and sodium to steers exposed to excessive heat load (maximum daily ambient temperature exceeded 32°C for three consecutive days) during seasonal summer conditions. Steers were assigned one of four treatments: (1) control; (2) potassium supplemented (diet containing 2.10% KHCO₃); (3) sodium supplemented (diet containing 1.10% NaCl); or (4) potassium and sodium supplemented (diet containing 2.10% KHCO₃ and 1.10% NaCl). Overall, additional KHCO₃ at the 2% level or NaCl at the 1% level did not improve performance or heat stress tolerance with these diet formulations. However, the addition of KHCO₃ did enhance water intake. Independent of treatment effects, TT of cattle displaying high, moderate, or low levels of stress suggest that cattle that do not adequately cool down at night are prone to achieving greater body temperatures during a subsequent hot day. Cattle that are prone to get hot but can cool at night can keep average tympanic temperatures at or near those of cattle that tend to consistently maintain lower peak and mean body temperatures. In addition, during cooler and moderately hot periods, cattle change TT in a stair-step or incremental pattern, while under hot conditions, average TT of group-fed cattle moves in conjunction with ambient conditions, indicating that thermoregulatory mechanisms are at or near maximum physiological capacity.

Pseudogene rescue: an adaptive mechanism of codon reassignment

Alterations to the genetic code--codon reassignments--have occurred many times in life's history, despite the fact that genomes are coadapted to their genetic codes and therefore alterations are likely to be maladaptive. A potential mechanism for adaptive codon reassignment, which could trigger either a temporary period of codon ambiguity or a permanent genetic code change, is the reactivation of a pseudogene by a nonsense suppressor mutant transfer RNA. I examine the population genetics of each stage of this process and find that pseudogene rescue is plausible and also readily explains some features of extant variability in genetic codes.

Epigenomic plasticity within populations: its evolutionary significance and potential

Epigenetics has progressed rapidly from an obscure quirk of heredity into a data-heavy 'omic' science. Our understanding of the molecular mechanisms of epigenomic regulation, and the extent of its importance in nature, are far from complete, but in spite of such drawbacks, population-level studies are extremely valuable: epigenomic regulation is involved in several processes central to evolutionary biology including phenotypic plasticity, evolvability and the mediation of intragenomic conflicts. The first studies of epigenomic variation within populations suggest high levels of phenotypically relevant variation, with the patterns of epigenetic regulation varying between individuals and genome regions as well as with environment. Epigenetic mechanisms appear to function primarily as genome defences, but result in the maintenance of plasticity together with a degree of buffering of developmental programmes; periodic breakdown of epigenetic buffering could potentially cause variation in rates of phenotypic evolution.

Replication of KIAA0350, IL2RA, RPL5 and CD58 as multiple sclerosis susceptibility genes in Australians

A recent genome-wide association study (GWAS) conducted by the International Multiple Sclerosis Genetics Consortium (IMSGC) identified a number of putative MS susceptibility genes. Here we have performed a replication study in 1134 Australian MS cases and 1265 controls for 17 risk-associated single nucleotide polymorphisms (SNPs) reported by the IMSGC. Of 16 SNPs that passed quality control filters, four, each corresponding to a different non-human leukocyte antigen (HLA) gene, were associated with disease susceptibility: KIAA0350 (rs6498169) P=0.001, IL2RA (rs2104286) P=0.033, RPL5 (rs6604026) P=0.041 and CD58 (rs12044852) P=0.042. There was no association (P=0.58) between rs6897932 in the IL7R gene and the risk of MS. No interactions were detected between the replicated IMSGC SNPs and HLA-DRB1*15, gender, disease course, disease progression or age-at-onset. We used a novel Bayesian approach to estimate the extent to which our data increased or decreased evidence for association with the six most-associated IMSGC loci. These analyses indicated that even modest P-values, such as those reported here, can contribute markedly to the posterior probability of 'true' association in replication studies. In conclusion, these data provide support for the involvement of four non-HLA genes in the pathogenesis of MS, and combined with previous data, increase to genome-wide significance (P=3 x 10(-8)) evidence of an association between KIAA0350 and risk of disease.

SNP mapping and candidate gene sequencing in the class I region of the HLA complex: searching for multiple sclerosis susceptibility genes in Tasmanians

This study is an extension to previously published work that has linked variation in the human leukocyte antigen (HLA) class I region with susceptibility to multiple sclerosis (MS) in Australians from the Island State of Tasmania. Single nucleotide polymorphism (SNP) mapping was performed on an 865-kb candidate region (D6S1683-D6S265) in 166 Tasmanian MS families, and seven candidate genes [ubiquitin D (UBD), olfactory receptor 2H3 (OR2H3), gamma-aminobutyric acid B receptor 1 (GABBR1), myelin oligodendrocyte glycoprotein (MOG), HLA-F, HLA complex group 4 (HCG4) and HLA-G] were resequenced. SNPs tagging the extended MS susceptibility haplotype were genotyped in an independent sample of 356 Australian MS trios and SNPs in the MOG gene were significantly over-transmitted to MS cases. We identified significant effects on MS susceptibility of HLA-A*2 (OR: 0.51; P = 0.05) and A*3 (OR: 2.85; P = 0.005), and two coding polymorphisms in the MOG gene (V145I: P = 0.01, OR: 2.2; V142L: P = 0.04, OR: 0.45) after full conditioning on HLA-DRB1. We have therefore identified plausible candidates for the causal MS susceptibility allele, and although not conclusive at this stage, our data provide suggestive evidence for multiple class I MS susceptibility genes.

Spontaneous loss of a conditionally dispensable chromosome from the Alternaria alternata apple pathotype leads to loss of toxin production and pathogenicity

The Alternaria alternata apple pathotype causes Alternaria blotch of susceptible apple cultivars through the production of a cyclic peptide, host-specific toxin, AM-toxin. We recently cloned a cyclic peptide synthetase gene, AMT, whose product catalyzes the production of AM-toxin and showed that it resides on chromosomes of 1.8 Mb or less, depending on the A. alternata apple pathotype strain. Reverse transcriptase (RT)-PCR, using primers specific to AMT, on laboratory sub-cultured strains previously shown to produce AM-toxin, identified one isolate that did not express the gene. A leaf necrosis bioassay confirmed an AM-toxin-minus phenotype. However, an original isolate of this strain which had not undergone sub-culture gave a positive result by both RTPCR and bioassay. Contour-clamped homogeneous electric field electrophoresis and Southern hybridization demonstrated the loss of a 1.1-Mb chromosome in the non-toxin-producing isolate. Since this chromosome can be entirely lost without affecting growth, but is necessary for pathogenicity, we propose it is a conditionally dispensable chromosome.

Gambling in the south: implications for physicians

Three historical cycles of legalized gambling have occurred in the South. Currently, every southern state has legalized some form of gaming. Adult past-year prevalence rates of problem gambling in southern states are within the national range. Higher prevalence rates occur in states with casinos and multiple forms of legalized gambling. States with lotteries have higher prevalence rates of adolescent problem gambling. Problem gambling can cause stress-induced physical diseases and psychiatric symptoms in gamblers and their families. Physicians can reduce personal, family, and social costs of problem gambling through increased awareness, strategic screening, and early intervention. Treatment approaches include inpatient treatment centers, self-help fellowship groups, and cognitive-behavioral and addiction-based psychotherapies. Although no standard pharmacologic treatments for gambling disorders exist, use of selective serotonin re-uptake inhibitors is under investigation. Referral resources are available to physicians in states with state-funded treatment programs for problem gamblers and/or state councils for problem gambling.

Daily smoking by Louisiana students: sixth through twelfth grades, 1996-1997

OBJECTIVES

We sought to determine the prevalence of daily smoking in Louisiana in grades 6 through 12 and to compare Louisiana students' daily smoking to that of national student and Louisiana adult rates.

METHODS

A statewide, randomized, stratified classroom-based survey of 11,736 subjects was done for the school year 1996-1997.

RESULTS

We found that 17.3% of sixth grade students smoked daily, increasing to 36.1% in twelfth grade. Native American (43.7%), white (37.8%), and public school (28.5%) students had the highest rates of daily smoking. Males and females smoked at similar rates. Louisiana students in grades 8, 10, and 12 smoked daily at much higher rates (331%, 193%, and 146%, respectively) than comparable national samples. In 1997, Louisiana students smoked daily at higher rates than did Louisiana adults (28.9% vs 24.6%), primarily due to higher rates of smoking in student females (27.1%) compared to adult females (20.4%).

CONCLUSIONS

Student smoking in Louisiana is a significant public health problem.

Optical light scatter imaging of cellular and sub-cellular morphology changes in stressed rat hippocampal slices

Optical imaging, such as transmission imaging, is used to study brain tissue injury. Transmission imaging detects cellular swelling via an increase in light transmitted by tissue slices due to a decrease in scattering particle concentration. Transmission imaging cannot distinguish sub-cellular particle size changes from cellular swelling or shrinkage. We present an optical imaging method, based on Mie scatter theory, to detect changes in sub-cellular particle size and concentration. The system uses a modified inverted microscope and a 16-bit cooled CCD camera to image tissue light scatter at two angles. Dual-angle scatter ratio imaging successfully discriminated latex microsphere suspensions of differing sizes (0.6, 0.8, 1 and 2 microm) and concentrations. We applied scatter imaging to hippocampal slices treated with 100 microM N-methyl-D-aspartate (NMDA) to model excitotoxic injury or -40 mOsm hypotonic perfusion solution to cause edema injury. We detected light scatter decreases similar to transmission imaging in the CA1 region of the hippocampus for both treatments. Using our system, we could distinguish between NMDA and hypotonic treatments on the basis of statistically significant (P<0.0003) differences in the scatter ratio measured in CA1. Scatter imaging should be useful in studying tissue injuries or activity resulting in brain tissue swelling as well as morphological changes in sub-cellular organelles such as mitochondrial swelling.

Gambling behavior of Louisiana students in grades 6 through 12

OBJECTIVES

The prevalence of problem and gambling behavior, the average age of onset of gambling behavior, and the co-occurrence of gambling disorder with substance use were determined in the Louisiana student population grades 6 through 12.

METHODS

A stratified randomized sample of 12,066 students in Louisiana schools during the 1996-1997 school year was surveyed about gambling behavior using the South Oaks Gambling Screen--Revised for Adolescents (SOGS-RA).

RESULTS

Fourteen percent of the students never gambled, 70.1 percent gambled without problems, 10.1 percent indicated problem gambling in the past year (level 2 according to the SOGS-RA), and 5.8 percent indicated pathological gambling behavior in the past year (level 3). Weekly or more frequent lottery play was reported by 16.5 percent. The average age of onset of gambling behavior was 11.2 years. Fifty-nine percent of the students with problem and pathological gambling behavior reported frequent alcohol and illicit drug use.

CONCLUSIONS

A significant minority of Louisiana students in grades 6 through 12-15.9 percent--acknowledged gambling-related symptoms and life problems. The association of problem and pathological gambling with use of alcohol, tobacco, and marijuana provides preliminary support for the inclusion of gambling among other adolescent risk behaviors.

Warfarin responses in total joint and hip fracture patients

Warfarin is considered as a narrow therapeutic drug-an agent for which small changes in dosage can lead to significant changes in response. The precision of warfarin treatment is especially relevant in an acute-care setting. In this study, we examined the effect of various risk factors on warfarin response in the early postoperative period after total joint arthroplasty and hip fracture fixation. A total of 260 patients placed on warfarin for thrombosis prophylaxis were retrospectively studied. Risk factors for warfarin sensitivity include age 80 years or older and hip fracture fixation. Patients aged 80 years or older who had hip fracture fixation were 4.7 times more likely to experience an international normalized ratio (INR) at or greater than 4.0 than other patients (therapeutic target range of INR, 1.8-2.2). The largest subtherapeutic risk group in this study were men weighing 180 lb or more. They were 5.7 times less likely to achieve an INR of 1.6 than the other patients. Factors such as body weight, age, and gender should be considered when ordering warfarin therapy. Current hospital warfarin sliding scales should be reviewed for their efficacy to ensure that the target outcome is achieved.

The snoring spectrum: acoustic assessment of snoring sound intensity in 1,139 individuals undergoing polysomnography

STUDY OBJECTIVES

To quantify the snoring sound intensity levels generated by individuals during polysomnographic testing and to examine the relationships between acoustic, polysomnographic, and clinical variables.

DESIGN

The prospective acquisition of acoustic and polysomnographic data with a retrospective medical chart review.

SETTING

A sleep laboratory at a primary care hospital.

PARTICIPANTS

All 1,139 of the patients referred to the sleep laboratory for polysomnographic testing from 1980 to 1994.

INTERVENTIONS

The acoustic measurement of snoring sound intensity during sleep concurrent with polysomnographic testing.

MEASUREMENTS AND RESULTS

Four decibel levels were derived from snoring sound intensity recordings. L1, L5, and L10 are measures of the sound pressure measurement in decibels employing the A-weighting network that yields the response of the human ear exceeded, respectively, for 1, 5, and 10% of the test period. The Leq is a measure of the A-weighted average intensity of a fluctuating acoustic signal over the total test period. L10 levels above 55 dBA were exceeded by 12.3% of the patients. The average levels of snoring sound intensity were significantly higher for men than for women. The levels of snoring sound intensity were associated significantly with the following: polysomnographic testing results, including the respiratory disturbance index (RDI), sleep latency, and the percentage of slow-wave sleep; demographic factors, including gender and body mass; and clinical factors, including snoring history, hypersomnolence, and breathing stoppage. Men with a body mass index of > 30 and an average snoring sound intensity of > 38 dBA were 4.1 times more likely to have an RDI of > 10.

CONCLUSIONS

Snoring sound intensity levels are related to a number of demographic, clinical, and polysomnographic test results. Snoring sound intensity is closely related to apnea/hypopnea during sleep. The noise generated by snoring can disturb or disrupt a snorer's sleep, as well as the sleep of a bed partner.