Biology subjects

Yeh, P.

Publications and source records attributed to Yeh, P..

6 recordsLinked to original sources

bioRxiv2026

Identification and characterization of a human antibody profile inversely associated with adverse cardiovascular events

Objective: The immune response is linked to the progression of atherosclerotic cardiovascular disease (CVD). We sought to characterize a predictive cardiovascular antibody biomarker using two independent cohorts. Approach and Results: A human IgG profile serendipitously identified by ELISA was quantified in a well characterized cohort of 359 patients with a history of coronary artery disease (CAD) who experienced a total of 71 incident adverse CVD events (death, myocardial infarction, and stroke) over a median 4.1-year follow-up. Using Cox proportional hazard regression analysis, low biomarker levels were an independent predictor of adverse cardiovascular outcomes after adjustment for age, sex, diabetes mellitus, estimated glomerular filtration rate, presence of obstructive CAD, heart failure, total cholesterol, and high-density lipoprotein (HDL) cholesterol (adjusted hazard ratio of 1.90 [95% CI: 1.03 to 3.49; p=0.038] between lowest and highest tertiles). Validation was then performed in a larger secondary cohort using 4356 baseline samples from the Multi-Ethnic Study of Atherosclerosis (MESA), a prospective study of cardiovascular outcomes resulting in adjusted odds ratio of 50.5 per unit decrease in log-transformed biomarker [95% CI: 2.4 to 2773.1; p=0.030] over one year by logistic regression analysis. Conclusions: Low levels of human IgG antibodies targeting Bovidae IgG are independently associated with increased incidence of CVD events in patients with or without a history of CAD, indicating the potential clinical predictive power of this antibody profile as an inverse biomarker for CVD.

immunology↗

bioRxiv2024

Unexpected levels of antibiotic resistance in marine bacterial communities not solely explained by urban river discharge

Driven by anthropogenic pressures, antibiotic resistance has become more prevalent within urban bacterial communities over recent decades. In general, resistance is expected to spread from highly impacted areas into surrounding environments as the spatial patterns of resistance reflect the balance between the ability of dispersal and horizontal gene transfer to spread resistance, and the effects of dilution or selection driven by other environmental or ecological factors that change along these gradients. However, the strength and scale of this effect is less clear, especially in coastal environments. We investigated antibiotic resistance of bacterial communities along a transect from a freshwater site in the Los Angeles River (surrounded by high-density urban development) out into the San Pedro Basin in the Pacific Ocean. We determined the minimum concentration of twelve different antibiotics needed to inhibit the growth of bacterial communities across eight sites. We also examined community composition and the prevalence of known genes related to antibiotic resistance from anthropogenic sources in each sample using 16S rRNA sequencing and qPCR. In contrast to our expectations, marine bacteria communities displayed higher resistance than the freshwater LA River community. Rather than the presence of known resistance genes or proximity to urban impacts, patterns of resistance were more strongly associated with the higher species diversity found in marine communities. These unexpected results open new opportunities to determine why marine bacterial communities possess high resistance and the repercussions for potentially pathogenic bacteria and their impacts on the health of humans and wildlife.

microbiology↗

bioRxiv2024

Evolution Under Thermal Stress Affects Escherichia colis Resistance to Antibiotics

Exposure to both antibiotics and temperature changes can induce similar physiological responses in bacteria. Thus, changes in growth temperature may affect antibiotic resistance. Previous studies have found that evolution under antibiotic stress causes shifts in the optimal growth temperature of bacteria. However, little is known about how evolution under thermal stress affects antibiotic resistance. We examined 100+ heat-evolved strains of Escherichia coli that evolved under thermal stress. We asked whether evolution under thermal stress affects optimal growth temperature, if there are any correlations between evolving in high temperatures and antibiotic resistance, and if these strains antibiotic efficacy changes depending on the local environments temperature. We found that: (1) surprisingly, most of the heat-evolved strains displayed a decrease in optimal growth temperature and overall growth relative to the ancestor strain, (2) there were complex patterns of changes in antibiotic resistance when comparing the heat-evolved strains to the ancestor strain, and (3) there were few significant correlations among changes in antibiotic resistance, optimal growth temperature, and overall growth. ImportanceEscherichia coli, a bacteria species often found within the intestinal tract of warm-blooded organisms, can be harmful to humans. Like all species of bacteria, E. coli can evolve, particularly in the presence of stressful conditions such as extreme temperatures or antibiotic treatments. Recent evidence suggests that when encountering one source of stress, an organisms ability to deal with a different source of stress is also affected. With global climate change and the continued evolution of antibiotic-resistant bacteria, the need to further investigate how temperature and antibiotics interact is clear. The significance of our research is in identifying possible correlations between temperature and antibiotic stress, broadening our understanding of how stressors affect organisms, and allowing for insights into possible future evolutionary pathways.

evolutionary biology↗

bioRxiv2022

Phenotypic plasticity and the anthropause: an urban bird becomes less aggressive

Urban areas often impose strong, novel selection pressures on wildlife. Phenotypic plasticity is an important mechanism helping organisms establish populations in novel environments. Phenotypic plasticity can be difficult to study in urban wildlife because many urban environmental variables are challenging to isolate and manipulate experimentally. We took advantage of the COVID-19 lockdowns to assess whether urban birds expressed aggression differently when relieved from frequent encounters with humans. We measured the territorial aggression responses of resident dark-eyed juncos (Junco hyemalis) on an urban college campus in Los Angeles, USA. We found that the population overall displayed significantly reduced aggression in pandemic year 2021 compared to the typical year 2019. Furthermore, individuals measured in both 2019 and 2021 showed significantly reduced aggression during 2021, demonstrating that individual birds maintain phenotypic plasticity in this trait. Our results show that human disturbance likely has a significant effect on the aggressive behavior of urban birds.

animal behavior and cognition↗

bioRxiv2021

Estimating Microbial Population Data from Optical Density

The spectrophotometer has been used for decades to measure the density of bacterial populations as the turbidity expressed as optical density - OD. However, the OD alone is an unreliable metric and is only proportionately accurate to cell titers to about an OD of 0.1. The relationship between OD and cell titer depends on the configuration of the spectrophotometer, the length of the light path through the culture, the size of the bacterial cells, and the cell culture density. We demonstrate the importance of plate reader calibration to identify the exact relationship between OD and cells/ml. We use four bacterial genera and two sizes of micro-titer plates (96-well and 384-well) and show that the cell/ml per unit OD depends heavily on the bacterial cell size and plate size. We applied our calibration curve to real growth curve data and conclude the cells/ml - rather than OD - is a metric that can be used to directly compare results across experiments, labs, instruments, and species.

microbiology↗

bioRxiv2020

Antibiotics shift the temperature response curve of Escherichia coli growth

Temperature variation--through time and across climatic gradients--affects individuals, populations, and communities. Yet how the thermal response of biological systems is altered by environmental stressors is poorly understood. Here we quantify two key features--optimal temperature and temperature breadth--to investigate how temperature responses vary in the presence of antibiotics. We use high-throughput screening to measure growth of Escherichia coli under single and pairwise combinations of 12 antibiotics across seven temperatures that range from 22{degrees}C to 46{degrees}C. We find that antibiotic stress often results in considerable changes in the optimal temperature for growth and a narrower temperature breadth. The direction of the optimal temperature shifts can be explained by the similarities between antibiotic-induced and temperature-induced damage to the physiology of the bacterium. We also find that the effects of pairs of stressors in the temperature response can often be explained by just one antibiotic out of the pair. Our study has implications for a general understanding of how ecological systems adapt and evolve to environmental changes.

ecology↗