Publications by authors named "John A Johnson"

Two new lipopeptaibols, tolypocaibols A () and B (), and the mixed NRPS-polyketide-shikimate natural product maximiscin [(/)-)] were isolated from a sp. fungal endophyte of the marine alga . Analysis of NMR and mass spectrometry data revealed the amino acid sequences of the lipopeptaibols, which both comprise 11 residues with a valinol C-terminus and a decanoyl acyl chain at the N-terminus.

View Article and Find Full Text PDF

Punctaporonins T () and U (), new caryophyllene sesquiterpenes, were isolated with three known punctaporonins, A (), B (), and C (), from the endophytic fungus (TC2-041). The structures and relative configurations of punctaporonins T and U were elucidated based on a combination of HRESIMS, 1D/2D NMR spectroscopic analysis, and X-ray diffraction analysis, while their absolute configuration is presumed to be consistent with the co-isolated - on biogenetic arguments. Compound showed weak inhibitory activity against both and .

View Article and Find Full Text PDF

Objectives: The goal of the study was to determine an association of cardiac ventricular substrate with thrombotic stroke (TS), cardioembolic stroke (ES) and intracerebral haemorrhage (ICH).

Design: Prospective cohort study.

Setting: The Atherosclerosis Risk in Communities (ARIC) study in 1987-1989 enrolled adults (45-64 years), selected as a probability sample from four US communities (Minneapolis, Minnesota; Washington, Maryland; Forsyth, North Carolina; Jackson, Mississippi).

View Article and Find Full Text PDF

One explanation for why people engage in frightening fictional experiences is that these experiences can act as simulations of actual experiences from which individuals can gather information and model possible worlds. Conducted during the COVID-19 pandemic, this study (n = 310) tested whether past and current engagement with thematically relevant media fictions, including horror and pandemic films, was associated with greater preparedness for and psychological resilience toward the pandemic. Since morbid curiosity has previously been associated with horror media use during the COVID-19 pandemic, we also tested whether trait morbid curiosity was associated with pandemic preparedness and psychological resilience during the COVID-19 pandemic.

View Article and Find Full Text PDF

Assessment of individual differences in personality traits is arguably one of the hallmarks of psychological research. Testing the structural validity of trait measurements is paramount in this endeavor. In the current study, we investigated 30 facet traits in one of the accessible and comprehensive public-domain Five Factor Model (FFM) personality inventories, IPIP-NEO-120 (Johnson, 2014), using one of the largest US samples to date ( = 320,128).

View Article and Find Full Text PDF

Psychologists often argue that sex roles direct different types of socializing behaviors toward males and females and that this differential treatment, in turn, leads to sex differences in personality. Widely cited in support of this thesis has been the Fels longitudinal study finding that dependency and passivity are stable from childhood to adulthood for females only and aggressiveness and sexuality for males only. The present article explains why the type of sex differences in personality stability cited by Fels researchers actually contradicts the view that sex role expectations cause these differences.

View Article and Find Full Text PDF

Rationale: MicroRNAs (miRs) are small, non-coding RNAs that function to post-transcriptionally regulate target genes. First transcribed as primary miR transcripts (pri-miRs), they are enzymatically processed by Drosha into premature miRs (pre-miRs) and further cleaved by Dicer into mature miRs. Initially discovered to desensitize β-adrenergic receptor (βAR) signaling, β-arrestins are now well-appreciated to modulate multiple pathways independent of G protein signaling, a concept known as biased signaling.

View Article and Find Full Text PDF

Background: The treatment of microbial infections is becoming increasingly challenging because of limited therapeutic options and the growing number of pathogenic strains that are resistant to current antibiotics. There is an urgent need to identify molecules with novel modes of action to facilitate the development of new and more effective therapeutic agents. The anti-mycobacterial activity of the C17 diyne natural products falcarinol and panaxydol has been described previously; however, their mode of action remains largely undetermined in microbes.

View Article and Find Full Text PDF

Ethnopharmacological Relevance: The purple pitcher plant, Sarracenia purpurea, is a medicinal plant used by the Canadian First Nations to treat a wide variety of illnesses. The Mi'kmaq and Wolastoqiyik (Maliseet) peoples of Eastern Canada have traditionally used infusions of S. purpurea for the treatment of tuberculosis-like symptoms.

View Article and Find Full Text PDF

The crude extract of Aspergillusfumigatus isolate AF3-093A, an endophyte of the brown alga Fucus vesiculosus, showed significant antimicrobial activity in initial bioactivity screens. Bioassay-guided fractionation of the extract led to the isolation of flavipin, chaetoglobosin A and chaetoglobosin B, all of which inhibited the growth of Staphylococcus aureus, methicillin-resistant S. aureus and Mycobacterium tuberculosis H37Ra.

View Article and Find Full Text PDF

An extract of an unidentified endophyte from the Canadian medicinal plant Heracleum maximum exhibited a unique metabolomic profile and significant antimycobacterial activity against Mycobacterium tuberculosis H37Ra. Bioassay guided fractionation of the extract led to the isolation of phomopsolide A (1) and 6(E)-phomopsolide A (2). This is the first report of antimycobacterial activity for 1 and 2.

View Article and Find Full Text PDF

Antimycobacterial extracts of a Penicillium sp. (isolate HL4-159-41B) and a Coniothyrium sp. (isolate HL6-097-027B) isolated from the rhizomes of the Canadian medicinal plant Aralia nudicaulis were found to contain palitantin (1) and botrallin (2), craterellin C (3), mycosporulone (4), spiromassaritone (5), and massarigenin D (6) respectively.

View Article and Find Full Text PDF

Post-translational modification represents an important mechanism to regulate protein function in cardiac cells. Ubiquitin (Ub) and ubiquitin-like proteins (UBLs) are a family of protein modifiers that share a certain extent of sequence and structure similarity. Conjugation of Ub or UBLs to target proteins is dynamically regulated by a set of UBL-specific enzymes and modulates the physical and physiological properties of protein substrates.

View Article and Find Full Text PDF

Previously, we demonstrated protection against hypoxic injury in neonatal cardiac myocytes and reduced release of cardiac troponin I from perfused rat hearts by a novel peptide inhibitor [NH2-YGRKKRRQRRRMLATRALSLIGKRAISTSVCAGRKLALKTIDWVSFDYKDDDDK-] of the delta protein kinase C (δPKC) interaction with the "d" subunit of mitochondrial F1Fo ATP synthase (dF1Fo). This peptide was developed in our laboratory and contains: an HIV-Tat protein transduction domain; a mitochondrial targeting motif; the δPKC-dF1Fo inhibitor sequence; and a FLAG epitope. In the present study the δPKC-dF1Fo inhibitor attenuated co-immunoprecipitation of δPKC with dF1Fo, improved recovery of contractility, diminished levels of tissue t-carbonyls and 4-hydroxy-2-nonenal (HNE), and reduced 2,3,5-triphenyltetrazolium chloride-monitored infarct size following simulated global ischemia/reperfusion (IR) exposures.

View Article and Find Full Text PDF

Most stars become white dwarfs after they have exhausted their nuclear fuel (the Sun will be one such). Between one-quarter and one-half of white dwarfs have elements heavier than helium in their atmospheres, even though these elements ought to sink rapidly into the stellar interiors (unless they are occasionally replenished). The abundance ratios of heavy elements in the atmospheres of white dwarfs are similar to the ratios in rocky bodies in the Solar System.

View Article and Find Full Text PDF

Two new dibenz[b,f]oxepins, empetroxepins A and B (1 and 2), and seven known compounds (3-9) were isolated from an extract of the Canadian medicinal plant Empetrum nigrum that significantly inhibited the growth of Mycobacterium tuberculosis H37Ra. The structures of 1 and 2 were established through analysis of NMR and MS data. The antimycobacterial activity of the plant extract was attributed primarily to the presence of two chalcone derivatives (6 and 7) that exhibited selective antimycobacterial activity (IC50 values of 23.

View Article and Find Full Text PDF

Ethnopharmacological Relevance: Alnus incana, commonly known as the gray or speckled alder, is a medicinal plant used by some Canadian First Nations to treat symptoms associated with tuberculosis. The aim of this study was to assess the anti-mycobacterial activity of an Alnus incana bark extract and to identify the active constituents of the extract.

Materials And Methods: Methanolic extracts of the bark of A.

View Article and Find Full Text PDF

An extract of Seimatosporium sp., an endophyte from the Canadian medicinal plant Hypericum perforatum, exhibited significant antifungal and antimycobacterial activity against Candida albicans and Mycobacterium tuberculosis H37Ra. Bioassay guided fractionation led to the isolation of (-)-avenaciolide as the only bioactive constituent of the extract.

View Article and Find Full Text PDF

Introduction: Because of increased resistance to current drugs, there is an urgent need to discover new anti-mycobacterial compounds for the development of novel anti-tuberculosis drugs. The microplate resazurin assay (MRA) is commonly used to evaluate natural products and synthetic compounds for anti-mycobacterial activity. However, the assay can be problematic and unreliable when screening methanolic phytochemical extracts.

View Article and Find Full Text PDF