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Peggy S Lai

Publications and source records attributed to Peggy S Lai.

2 recordsLinked to original sources

Reframing the asthma microbiome: Multikingdom, multisite, and multiomic perspectives.

The field of asthma microbiome research has shifted rapidly in recent years. Advances in sequencing technology have led to an increased ability to characterize multikingdom microbial species and integration with host -omics profiling to enhance future translational applications. Traditional bacteria-centric, cross-sectional studies are giving way to mechanistic frameworks that incorporate fungi, viruses, and host-immune interactions. In this state-of-the-art review of emerging concepts in microbiome asthma research, we first propose a structured framework to consider microbiome studies across 5 major domains-microbial kingdom, site of sampling, integration with host -omics, clinical outcome domain, and translational relevance-in order to synthesize recent high-impact human microbiome studies in asthma. We highlight emerging evidence that fungal and viral communities contribute independently to asthma risk and that human microbial communities are linked to distinct inflammatory and immune pathways shaped by host genetic susceptibility.

Asthma↗

Alternative pathways of sterol synthesis in yeast. Use of C(27) sterol tracers to study aberrant double-bond migrations and evaluate their relative importance.

Yeast produce traces of aberrant sterols by minor alternative pathways, which can become significant when normal metabolism is blocked by inhibitors or mutations. We studied sterols generated in the absence of the delta(8)-delta(7) isomerase (Erg2p) or delta(5) desaturase (Erg3p) by incubating three mutant strains of Saccharomyces cerevisiae with 5 alpha-cholest-8-en-3beta-ol, 8-dehydrocholesterol (delta(5,8) sterol), or isodehydrocholesterol (delta(6,8) sterol), together with the corresponding 3 alpha-3H isotopomer. Nine different incubations gave altogether 16 sterol metabolites, including seven delta(22E) sterols formed by action of the yeast C-22 desaturase (Erg5p). These products were separated by silver-ion high performance liquid chromatography (Ag(+)-HPLC) and identified by gas chromatography-mass spectrometry, nuclear magnetic resonance spectroscopy, and radio-Ag(+)-HPLC. When delta(8)-delta(7) isomerization was blocked, exogenous delta(8) sterol underwent desaturation to delta(5,8), delta(6,8), and delta(8,14) sterols. Formation of delta(5,8) sterol was strongly favored over delta(6,8) sterol, but both pathways are essentially dormant under normal conditions of sterol synthesis. The delta(5,8) sterol was metabolically almost inert except for delta(22) desaturation, whereas the delta(6,8) sterol was readily converted to delta(5,7), delta(5,7,9(11)), and delta(7,9(11)) sterols. The combined results indicate aberrant metabolic pathways similar to those in mammalian systems. However, delta(5,7) sterol undergoes only slight isomerization or desaturation in yeast, an observation that accounts for the lower levels of delta(5,8) and delta(5,7,9(11)) sterols in wild-type yeast compared to Smith-Lemli-Opitz individuals.

Cholestadienols↗