The hypoxia-inducible factors (HIFs) 1α and 2α are key mammalian transcription factors that exhibit dramatic increases in both protein stability and intrinsic transcriptional potency during ...low-oxygen stress. This increased stability is due to the absence of proline hydroxylation, which in normoxia promotes binding of HIF to the von Hippel-Lindau (VHL tumor suppressor) ubiquitin ligase. We now show that hypoxic induction of the COOH-terminal transactivation domain (CAD) of HIF occurs through abrogation of hydroxylation of a conserved asparagine in the CAD. Inhibitors of Fe(II)- and 2-oxoglutarate-dependent dioxygenases prevented hydroxylation of the Asn, thus allowing the CAD to interact with the p300 transcription coactivator. Replacement of the conserved Asn by Ala resulted in constitutive p300 interaction and strong transcriptional activity. Full induction of HIF-1α and -2α, therefore, relies on the abrogation of both Pro and Asn hydroxylation, which during normoxia occur at the degradation and COOH-terminal transactivation domains, respectively.
The brown planthopper, Nilaparvata lugens, is an economically significant pest of rice throughout Asia and has evolved resistance to many insecticides including the neonicotinoid imidacloprid. The ...resistance of field populations of N. lugens to imidacloprid has been attributed to enhanced detoxification by cytochrome P450 monooxygenases (P450s), although, to date, the causative P450(s) has (have) not been identified. In the present study, biochemical assays using the model substrate 7‐ethoxycoumarin showed enhanced P450 activity in several resistant N. lugens field strains when compared with a susceptible reference strain. Thirty three cDNA sequences encoding tentative unique P450s were identified from two recent sequencing projects and by degenerate PCR. The mRNA expression level of 32 of these was examined in susceptible, moderately resistant and highly resistant N. lugens strains using quantitative real‐time PCR. A single P450 gene (CYP6ER1) was highly overexpressed in all resistant strains (up to 40‐fold) and the level of expression observed in the different N. lugens strains was significantly correlated with the resistance phenotype. These results provide strong evidence for a role of CYP6ER1 in the resistance of N. lugens to imidacloprid.
Mammalian cells adapt to hypoxic conditions through a transcriptional response pathway mediated by the hypoxia-inducible factor, HIF. HIF transcriptional activity is suppressed under normoxic ...conditions by hydroxylation of an asparagine residue within its C-terminal transactivation domain, blocking association with coactivators. Here we show that the protein FIH-1, previously shown to interact with HIF, is an asparaginyl hydroxylase. Like known hydroxylase enzymes, FIH-1 is an Fe(II)-dependent enzyme that uses molecular O(2) to modify its substrate. Together with the recently discovered prolyl hydroxylases that regulate HIF stability, this class of oxygen-dependent enzymes comprises critical regulatory components of the hypoxic response pathway.
In this trial in nondiabetic patients with insulin resistance and a recent ischemic stroke or transient ischemic attack, pioglitazone was associated with a lower risk of stroke and MI than was ...placebo but with a higher risk of weight gain, edema, and bone fracture.
Ischemic stroke and transient ischemic attack (TIA) affect more than 14 million persons worldwide annually.
1
,
2
Affected patients are at increased risk for future cardiovascular events,
3
,
4
and prevention of these adverse outcomes is a major goal in their care.
Treatment of insulin resistance represents a potential new preventive strategy that could be added to standard care after ischemic stroke or TIA.
5
Insulin resistance is nearly universal in patients with type 2 diabetes but is also present in more than 50% of patients without diabetes who have had an ischemic stroke or a TIA.
6
The presence of insulin resistance increases . . .
The suprachiasmatic nucleus (SCN) within the hypothalamus is a key brain structure required to relay light information to the body and synchronize cell and tissue level rhythms and hormone release. ...Specific subpopulations of SCN neurons, defined by their peptide expression, regulate defined SCN output. Here we focus on the vasoactive intestinal peptide (VIP) expressing neurons of the SCN. SCN VIP neurons are known to regulate circadian rhythms and reproductive function.
To specifically study SCN VIP neurons, we generated a novel knock out mouse line by conditionally deleting the SCN enriched transcription factor, Ventral Anterior Homeobox 1 (Vax1), in VIP neurons (Vax1
; Vax1
:Vip
).
We found that Vax1
females presented with lengthened estrous cycles, reduced circulating estrogen, and increased depressive-like behavior. Further, Vax1
males and females presented with a shortened circadian period in locomotor activity and
SCN circadian period. On a molecular level, the shortening of the SCN period was driven, at least partially, by a direct regulatory role of VAX1 on the circadian clock genes
and
. Interestingly, Vax1
females presented with increased expression of arginine vasopressin (
) in the paraventricular nucleus, which resulted in increased circulating corticosterone. SCN VIP and AVP neurons regulate the reproductive gonadotropin-releasing hormone (GnRH) and kisspeptin neurons. To determine how the reproductive neuroendocrine network was impacted in Vax1
mice, we assessed GnRH sensitivity to a kisspeptin challenge
. We found that GnRH neurons in Vax1
females, but not males, had an increased sensitivity to kisspeptin, leading to increased luteinizing hormone release. Interestingly, Vax1
males showed a small, but significant increase in total sperm and a modest delay in pubertal onset. Both male and female Vax1
mice were fertile and generated litters comparable in size and frequency to controls.
Together, these data identify VAX1 in SCN VIP neurons as a neurological overlap between circadian timekeeping, female reproduction, and depressive-like symptoms in mice, and provide novel insight into the role of SCN VIP neurons.
Alternative postharvest sanitizers to chlorine are of increasing interest for many organic growers and consumers. An emulsion of clove bud oil (CBO; 0.2 and 0.5%) or thyme oil (0.2 and 0.5%) was ...evaluated as a sanitizer for produce washing against a five-serovar cocktail of Salmonella on snacking peppers and compared for antimicrobial efficacy with sodium hypochlorite (200 ppm). To further evaluate these compounds, the sanitation efficacy of an emulsion was examined after the addition of 1% organic load (OL). Emulsion treatments at 0.2 and 0.5% thyme oil and 0.5% CBO were the least effected by OL and effectively reduced cross-contamination of Salmonella on clean peppers, in many cases to below the limit of detection (1 CFU/10 g; P < 0.05). Chlorine and 0.2% CBO were rendered ineffective by the addition of OL in preventing cross-contamination and performed similarly to the water control. For surface-inoculated peppers, none of the evaluated treatments performed better than a water-only wash. The antimicrobial efficacy of the essential oil emulsions in the presence of OL indicates these emulsions may be suitable replacements for chlorine in postharvest produce wash systems.
The endoplasmic reticulum (ER) is a membranous intracellular organelle and the first compartment of the secretory pathway. As such, the ER contributes to the production and folding of approximately ...one‐third of cellular proteins, and is thus inextricably linked to the maintenance of cellular homeostasis and the fine balance between health and disease. Specific ER stress signalling pathways, collectively known as the unfolded protein response (UPR), are required for maintaining ER homeostasis. The UPR is triggered when ER protein folding capacity is overwhelmed by cellular demand and the UPR initially aims to restore ER homeostasis and normal cellular functions. However, if this fails, then the UPR triggers cell death. In this review, we provide a UPR signalling‐centric view of ER functions, from the ER's discovery to the latest advancements in the understanding of ER and UPR biology. Our review provides a synthesis of intracellular ER signalling revolving around proteostasis and the UPR, its impact on other organelles and cellular behaviour, its multifaceted and dynamic response to stress and its role in physiology, before finally exploring the potential exploitation of this knowledge to tackle unresolved biological questions and address unmet biomedical needs. Thus, we provide an integrated and global view of existing literature on ER signalling pathways and their use for therapeutic purposes.
The current article reviews the most up‐to‐date literature on Endoplasmic Reticulum (ER) biology and articulates this information from a signalling perspective. Not only do we cover the basic cell biology aspects of adaptive ER signalling but also provide information about the latest discoveries on ER stress targeting drugs and their potential use in the clinic.
Summary
This randomized controlled trial evaluated the effect of resistance training frequency (0, 1, and 2 times/week) on cortical volumetric bone mineral density (vBMD) at the tibia in older women. ...There was no mean difference in change in tibial cortical vBMD in older women who engaged in resistance training (RT) one or two times/week compared with the control group over 12 months after adjusting for baseline values.
Introduction
National guidelines recommend RT two to three times/week to optimize bone health. Our objective was to determine the effect of a 12-month intervention of three different RT frequencies on tibial volumetric cortical density (CovBMD) in healthy older women.
Methods
We randomized participants to the following groups: (1) 2×/week balance and tone group (i.e., no resistance beyond body weight, BT), (2) 1×/week RT (RT1), and (3) 2×/week RT (RT2). Treatment allocation was concealed, and measurement team and the bone data analyst were blinded to group allocation. We used peripheral quantitative computed tomography to acquire one 2.3-mm scan at the 50 % tibia, and the primary outcome was CovBMD. Data were collected at baseline, 6 and 12 months, and we used linear mixed modeling to assess the effect at 12 months.
Results
We assessed 147 participants; 100 women provided data at all three points. Baseline unadjusted mean (SD) tibial CovBMD (in milligrams per cubic centimeter) at the 50 % site was 1,077.4 (43.0) (BT), 1,087.8 (42.0) (RT1), and 1,058.7 (60.4) (RT2). At 12 months, there were no statistically significant differences (−0.45 to −0.17 %) between BT and RT groups for mean difference in change in tibial CovBMD for exercise interventions (BT, RT1, RT2) after adjusting for baseline tibial CovBMD.
Conclusion
We note no mean difference in change in tibial CovBMD in older women who engaged in RT one or two times/week compared with the control group over 12 months. It is unknown if RT of 3× or 4×/week would be enough to promote a statistically significant difference in change of bone density.
This study describes a novel series of UDP-N-acetylglucosamine acyltransferase (LpxA) inhibitors that was identified through affinity-mediated selection from a DNA-encoded compound library. The ...original hit was a selective inhibitor of Pseudomonas aeruginosa LpxA with no activity against Escherichia coli LpxA. The biochemical potency of the series was optimized through an X-ray crystallography-supported medicinal chemistry program, resulting in compounds with nanomolar activity against P. aeruginosa LpxA (best half-maximal inhibitory concentration (IC50) <5 nM) and cellular activity against P. aeruginosa (best minimal inhibitory concentration (MIC) of 4 μg/mL). Lack of activity against E. coli was maintained (IC50 > 20 μM and MIC > 128 μg/mL). The mode of action of analogues was confirmed through genetic analyses. As expected, compounds were active against multidrug-resistant isolates. Further optimization of pharmacokinetics is needed before efficacy studies in mouse infection models can be attempted. To our knowledge, this is the first reported LpxA inhibitor series with selective activity against P. aeruginosa.
To determine the relationship between, and antibiotic resistance of, endotracheal tube (ET) biofilm and pulmonary pathogens in ventilator-associated pneumonia (VAP).
General intensive care units in ...two university teaching hospitals.
The microbiology of ET biofilm and tracheal samples from patients with and without VAP were compared. For individual patients, matching pairs of pathogens were confirmed as identical and characterised for antibiotic susceptibility.
40 intensive care unit patients - 20 with VAP, 20 without VAP as control. The duration of intubation (median and range) was 6.5 days (3-17) and 5 days (2-10), respectively.
Samples of tracheal secretions were taken during ventilation for bacteriological culture. Following extubation, ETs were examined for the presence of biofilm. Isolates of high pathogenic potential included Staphylococcus aureus, enterococci, Enterobacteriaceae, pseudomonads and Candida spp. Where the same microorganism was found on tracheal and ET samples by phenotyping, these were confirmed as identical by genotyping and characterised for antibiotic susceptibility in both the free floating and biofilm forms. Seventy per cent of patients with VAP had identical pathogens isolated from both ET biofilm and tracheal secretions. No pairing of pathogens was observed in control patients (p < 0.005). Susceptibility data for these pairs show that the ET acts as a reservoir for infecting microorganisms which exhibit significantly greater antibiotic resistance than their tracheal counterparts.
This investigation provides further evidence for the role of ET biofilm in VAP. The difficulty in eradicating an established microbial biofilm using antibiotics implies that increased attention must be directed towards modification of the ET to prevent or substantially reduce biofilm formation.
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