A tetrapeptide class of biased analgesics from an Australian fungus targets the µ-opioid receptor.

An Australian estuarine isolate of Penicillium sp. MST-MF667 yielded 3 tetrapeptides named the bilaids with an unusual alternating LDLD chirality. Given their resemblance to known short peptide opioid agonists, we elucidated that they were weak (Ki low micromolar) µ-opioid agonists, which led to the design of bilorphin, a potent and selective µ-opioid receptor (MOPr) agonist (Ki 1.1 nM). In sharp contrast to all-natural product opioid peptides that efficaciously recruit ß-arrestin, bilorphin is G protein biased, weakly phosphorylating the MOPr and marginally recruiting ß-arrestin, with no receptor internalization. Importantly, bilorphin exhibits a similar G protein bias to oliceridine, a small nonpeptide with improved overdose safety. Molecular dynamics simulations of bilorphin and the strongly arrestin-biased endomorphin-2 with the MOPr indicate distinct receptor interactions and receptor conformations that could underlie their large differences in bias. Whereas bilorphin is systemically inactive, a glycosylated analog, bilactorphin, is orally active with similar in vivo potency to morphine. Bilorphin is both a unique molecular tool that enhances understanding of MOPr biased signaling and a promising lead in the development of next generation analgesics.

Multi-vendor standardized sequence for edited magnetic resonance spectroscopy.

Spectral editing allows direct measurement of low-concentration metabolites, such as GABA, glutathione (GSH) and lactate (Lac), relevant for understanding brain (patho)physiology. The most widely used spectral editing technique is MEGA-PRESS, which has been diversely implemented across research sites and vendors, resulting in variations in the final resolved edited signal. In this paper, we describe an effort to develop a new universal MEGA-PRESS sequence with HERMES functionality for the major MR vendor platforms with standardized RF pulse shapes, durations, amplitudes and timings. New RF pulses were generated for the universal sequence. Phantom experiments were conducted on Philips, Siemens, GE and Canon 3 T MRI scanners using 32-channel head coils. In vivo experiments were performed on the same six subjects on Philips and Siemens scanners, and on two additional subjects, one on GE and one on Canon scanners. On each platform, edited MRS experiments were conducted with the vendor-native and universal MEGA-PRESS sequences for GABA (TE = 68 ms) and Lac editing (TE = 140 ms). Additionally, HERMES for GABA and GSH was performed using the universal sequence at TE = 80 ms. The universal sequence improves inter-vendor similarity of GABA-edited and Lac-edited MEGA-PRESS spectra. The universal HERMES sequence yields both GABA- and GSH-edited spectra with negligible levels of crosstalk on all four platforms, and with strong agreement among vendors for both edited spectra. In vivo GABA+/Cr, Lac/Cr and GSH/Cr ratios showed relatively low variation between scanners using the universal sequence. In conclusion, phantom and in vivo experiments demonstrate successful implementation of the universal sequence across all four major vendors, allowing editing of several metabolites across a range of TEs.

Separation and quantification of lactate and lipid at 1.3 ppm by diffusion-weighted magnetic resonance spectroscopy.

PURPOSE: To separate the spectrally overlapped lactate and lipid signals at 1.3 ppm using diffusion-weighted magnetic resonance spectroscopy (DW-MRS) based on their large diffusivity difference. METHODS: DW-MRS was applied to the gel phantoms containing lactate and lipid droplets, and to the rat brain tumors. Lactate and lipid signals and their apparent diffusion coefficients were computed from the diffusion-weighted proton spectra. Biexponential fitting and direct spectral subtraction approaches were employed and compared. RESULTS: DW-MRS could effectively separate lactate and lipid signals both in phantoms and rat brain C6 glioma by biexponential fitting. In phantoms, lactate and lipid signals highly correlated with the known lactate concentration and lipid volume fractions. In C6 glioma, both lactate and lipid signals were detected, and the lipid signal was an order of magnitude higher than lactate signal. The spectral subtraction approach using three diffusion weightings also allowed the separation of lactate and lipid signals, yielding results comparable to those by the biexponential fitting approach. CONCLUSION: DW-MRS presents a new approach to separate and quantify spectrally overlapped molecules and/or macromolecules, such as lactate and lipid, by using the diffusivity difference associated with their different sizes or mobility within tissue microstructure. Magn Reson Med 77:480-489, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Detection of extracellular matrix degradation in intervertebral disc degeneration by diffusion magnetic resonance spectroscopy.

PURPOSE: To investigate whether diffusion magnetic resonance spectroscopy (MRS) can detect the extracellular matrix (ECM) degradation during intervertebral disc degeneration (IVDD) by the increased mobility of ECM macromolecules such as proteoglycans and collagens. METHODS: Fresh bovine intervertebral discs were injected with papain solution to induce ECM degradation. The apparent diffusion coefficients (ADCs), T2 values, and contents of ECM macromolecules and water resonances were measured longitudinally in the nucleus pulposus. RESULTS: The macromolecule ADCs increased drastically at day 1 after papain injection, and continued increasing for 5 days. In contrast, the proteoglycan content exhibited a small and slow decrease after injection while the macromolecule T2 values, water T2, ADC, and content showed slight increase or no change. The protein gel electrophoresis analysis confirmed the gradually increased ECM fragmentation in accordance with the observed macromolecule ADC increases. CONCLUSION: Diffusion MRS provides a new method to characterize the ECM degradation processes directly and sensitively. Macromolecule ADCs offer a potentially more sensitive and earlier marker for ECM degradation than the proteoglycan content and T2, and water MR properties during early IVDD. Such diffusion approach offers the possibility to directly monitor ECM integrity and degradation processes in vivo at molecular and microstructural levels in both preclinical and clinical settings.

Diffusion magnetic resonance monitors intramyocellular lipid droplet size in vivo.

PURPOSE: Intramyocellular lipid (IMCL) droplets are dynamic organelles whose morphology reflects their vital roles in lipid synthesis, usage, and storage in muscle energy metabolism. To develop noninvasive means to measure droplet microstructure in vivo, we investigated the molecular diffusion behavior of IMCL with diffusion magnetic resonance spectroscopy. METHODS: Using extremely large diffusion weighting, we measured the IMCL apparent diffusion coefficients (ADCs) in hindlimb muscle of rodents from normal feeding, 60-h fasting, streptozotocin-induced diabetic, and high-fat-diet-induced obese groups. RESULTS: IMCL ADCs decreased markedly with diffusion time, confirming the restricted diffusion of lipid molecules within IMCL droplets. IMCL droplet size, determined by transmission electron microscopy, was closely correlated with ADC. IMCL ADC was sensitive to metabolic alterations, decreasing in the 60-h fasting and diabetic groups while increasing in the obese group. These findings indicated that the IMCL droplet size decreased following 60-h fasting and in STZ-induced diabetes but increased in high-fat-diet-induced obesity. CONCLUSION: MR diffusion characterization of IMCL droplet size provides a unique means to examine the intracellular lipid dynamics and metabolic abnormalities in vivo.

Effects of progesterone vs. dexamethasone on brain oedema and inflammatory responses following experimental brain resection.

BACKGROUND: Dexamethasone (DEXA) is commonly used to reduce brain swelling during neurosurgical procedures. DEXA, however, has many side-effects that can increase the risks of post-operative complications. In contrast, progesterone (PRO) has fewer side-effects and has been found to be neuroprotective on traumatic brain injury (TBI). Whether PRO may be used as an alternative to DEXA during routine procedures has not been fully explored. OBJECT: To compare the effects of DEXA and PRO on surgical brain injury (SBI). METHODS: Seventy-five adult male Sprague Dawley rats were randomized into five groups: (1) SBI + drug vehicle (peanut oil, 1 ml kg(-1)); (2) SBI + DEXA (1 mg kg(-1)); (3) SBI + low-dose PRO (10 mg kg(-1)); (4) SBI + high-dose PRO (20 mg kg(-1)); and (5) sham SBI + drug vehicle. Magnetic resonance imaging study and assessments of brain water content (BWC), blood-brain barrier (BBB) permeability, cellular inflammatory responses and matrix metalloproteinase 9 (MMP-9) expression were conducted. RESULTS: This model consistently resulted in increased BWC and BBB disruption. PRO reduced astrocyte and microglia responses and attenuated brain oedema with preservation of BBB. A significant down-regulation of MMP-9 expression occurred in the PRO 20 group. CONCLUSIONS: PRO is as effective as DEXA in reducing brain oedema and inflammation following SBI; 10 mg kg(-1) of PRO was demonstrated to be more effective in relieving acute cellular inflammatory responses.

Assessing Brain Metabolism With 7-T Proton Magnetic Resonance Spectroscopy in Patients With First-Episode Psychosis.

Importance: The use of high-field magnetic resonance spectroscopy (MRS) in multiple brain regions of a large population of human participants facilitates in vivo study of localized or diffusely altered brain metabolites in patients with first-episode psychosis (FEP) compared to healthy participants. Objective: To compare metabolite levels in 5 brain regions between patients with FEP (evaluated within 2 years of onset) and healthy controls, and to explore possible associations between targeted metabolite levels and neuropsychological test performance. Design, Setting, and Participants: Cross-sectional design used 7-T MRS at a research MR imaging facility in participants recruited from clinics at the Johns Hopkins Schizophrenia Center and the local population. Eighty-one patients who had received a DSM-IV diagnosis of FEP within the last 2 years and 91 healthy age-matched (but not sex-matched) volunteers participated. Main Outcomes and Measures: Brain metabolite levels including glutamate, glutamine, γ-aminobutyric acid (GABA), N-acetylaspartate, N-acetylaspartyl glutamate, and glutathione, as well as performance on neuropsychological tests. Results: The mean (SD) age of 81 patients with FEP was 22.3 (4.4) years and 57 were male, while the mean (SD) age of 91 healthy participants was 23.3 (3.9) years and 42 were male. Compared with healthy participants, patients with FEP had lower levels of glutamate (F1,162 = 8.63, P = .02), N-acetylaspartate (F1,161 = 5.93, P = .03), GABA (F1,163 = 6.38, P = .03), and glutathione (F1,162 = 4.79, P = .04) in the anterior cingulate (all P values are corrected for multiple comparisons); lower levels of N-acetylaspartate in the orbitofrontal region (F1,136 = 7.23, P = .05) and thalamus (F1,133 = 6.78, P = .03); and lower levels of glutathione in the thalamus (F1,135 = 7.57, P = .03). Among patients with FEP, N-acetylaspartate levels in the centrum semiovale white matter were significantly correlated with performance on neuropsychological tests, including processing speed (r = 0.48; P < .001), visual (r = 0.33; P = .04) and working (r = 0.38; P = .01) memory, and overall cognitive performance (r = 0.38; P = .01). Conclusions and Relevance: Seven-tesla MRS offers insights into biochemical changes associated with FEP and may be a useful tool for probing brain metabolism that ranges from neurotransmission to stress-associated pathways in participants with psychosis.

Sulforaphane Augments Glutathione and Influences Brain Metabolites in Human Subjects: A Clinical Pilot Study.

Schizophrenia and other neuropsychiatric disorders await mechanism-associated interventions. Excess oxidative stress is increasingly appreciated to participate in the pathophysiology of brain disorders, and decreases in the major antioxidant, glutathione (GSH), have been reported in multiple studies. Technical cautions regarding the estimation of oxidative stress-related changes in the brain via imaging techniques have led investigators to explore peripheral GSH as a possible pathological signature of oxidative stress-associated brain changes. In a preclinical model of GSH deficiency, we found a correlation between whole brain and peripheral GSH levels. We found that the naturally occurring isothiocyanate sulforaphane increased blood GSH levels in healthy human subjects following 7 days of daily oral administration. In parallel, we explored the potential influence of sulforaphane on brain GSH levels in the anterior cingulate cortex, hippocampus, and thalamus via 7-T magnetic resonance spectroscopy. A significant positive correlation between blood and thalamic GSH post- and pre-sulforaphane treatment ratios was observed, in addition to a consistent increase in brain GSH levels in response to treatment. This clinical pilot study suggests the value of exploring relationships between peripheral GSH and clinical/neuropsychological measures, as well as the influences sulforaphane has on functional measures that are altered in neuropsychiatric disorders.

A systematic review of the effectiveness of occupational health and safety training.

OBJECTIVES: Training is regarded as an important component of occupational health and safety (OHS) programs. This paper primarily addresses whether OHS training has a beneficial effect on workers. The paper also examines whether higher engagement OHS training has a greater effect than lower engagement training. METHODS: Ten bibliographic databases were searched for pre-post randomized trial studies published in journals between 1996 and November 2007. Training interventions were included if they were delivered to workers and were concerned with primary prevention of occupational illness or injury. The methodological quality of each relevant study was assessed and data was extracted. The impacts of OHS training in each study were summarized by calculating the standardized mean differences. The strength of the evidence on training's effectiveness was assessed for (i) knowledge, (ii) attitudes and beliefs, (iIi) behaviors, and (iv) health using the US Centers for Disease Control and Prevention's Guide to Community Preventive Services, a qualitative evidence synthesis method. RESULTS: Twenty-two studies met the relevance criteria of the review. They involved a variety of study populations, occupational hazards, and types of training. Strong evidence was found for the effectiveness of training on worker OHS behaviors, but insufficient evidence was found of its effectiveness on health (ie, symptoms, injuries, illnesses). CONCLUSIONS: The review team recommends that workplaces continue to deliver OHS training to employees because training positively affects worker practices. However, large impacts of training on health cannot be expected, based on research evidence.