Dimethyl carbonate as potential reactant in non-catalytic biodiesel production by supercritical method

In this study, the non-catalytic supercritical method has been studied in utilizing dimethyl carbonate. It was demonstrated that, the supercritical dimethyl carbonate process without any catalysts applied, converted triglycerides to fatty acid methyl esters with glycerol carbonate and citramalic acid as by-products, while free fatty acids were converted to fatty acid methyl esters with glyoxal. After 12 min of reaction at 350 degrees C/20 MPa, rapeseed oil treated with supercritical dimethyl carbonate reached 94% (w/w) yield of fatty acid methyl ester. The by-products from this process which are glycerol carbonate and citramalic acid are much higher in value than glycerol produced by the conventional process. In addition, the yield of the fatty acid methyl esters as biodiesel was almost at par with supercritical methanol method. Therefore, supercritical dimethyl carbonate process can be a good candidate as an alternative biodiesel production process.     

Activated polyamine catabolism depletes acetyl-CoA pools and suppresses prostate tumor growth in TRAMP mice

The enzyme spermidine/spermine N(1)-acetyltransferase (SSAT) regulates the catabolism and export of intracellular polyamines. We have previously shown that activation of polyamine catabolism by conditional overexpression of SSAT has antiproliferative consequences in LNCaP prostate carcinoma cells. Growth inhibition was causally linked to high metabolic flux arising from a compensatory increase in polyamine biosynthesis. Here we examined the in vivo consequences of SSAT overexpression in a mouse model genetically predisposed to develop prostate cancer. TRAMP (transgenic adenocarcinoma of mouse prostate) female C57BL/6 mice carrying the SV40 early genes (T/t antigens) under an androgen-driven probasin promoter were cross-bred with male C57BL/6 transgenic mice that systemically overexpress SSAT. At 30 weeks of age, the average genitourinary tract weights of TRAMP mice were approximately 4 times greater than those of TRAMP/SSAT bigenic mice, and by 36 weeks, they were approximately 12 times greater indicating sustained suppression of tumor outgrowth. Tumor progression was also affected as indicated by a reduction in the prostate histopathological scores. By immunohistochemistry, SV40 large T antigen expression in the prostate epithelium was the same in TRAMP and TRAMP/SSAT mice. Consistent with the 18-fold increase in SSAT activity in the TRAMP/SSAT bigenic mice, prostatic N(1)-acetylspermidine and putrescine pools were remarkably increased relative to TRAMP mice, while spermidine and spermine pools were minimally decreased due to a compensatory 5-7-fold increase in biosynthetic enzymes activities. The latter led to heightened metabolic flux through the polyamine pathway and an associated approximately 70% reduction in the SSAT cofactor acetyl-CoA and a approximately 40% reduction in the polyamine aminopropyl donor S-adenosylmethionine in TRAMP/SSAT compared with TRAMP prostatic tissue. In addition to elucidating the antiproliferative and metabolic consequences of SSAT overexpression in a prostate cancer model, these findings provide genetic support for the discovery and development of specific small molecule inducers of SSAT as a novel therapeutic strategy targeting prostate cancer.     

Effects of traditionally used anxiolytic botanicals on enzymes of the gamma-aminobutyric acid (GABA) system

In Canada, the use of botanical natural health products (NHPs) for anxiety disorders is on the rise, and a critical evaluation of their safety and efficacy is required. The purpose of this study was to determine whether commercially available botanicals directly affect the primary brain enzymes responsible for gamma-aminobutyric acid (GABA) metabolism. Anxiolytic plants may interact with either glutamic acid decarboxylase (GAD) or GABA transaminase (GABA-T) and ultimately influence brain GABA levels and neurotransmission. Two in vitro rat brain homogenate assays were developed to determine the inhibitory concentrations (IC50) of aqueous and ethanolic plant extracts. Approximately 70% of all extracts that were tested showed little or no inhibitory effect (IC50 values greater than 1 mg/mL) and are therefore unlikely to affect GABA metabolism as tested. The aqueous extract of Melissa officinalis (lemon balm) exhibited the greatest inhibition of GABA-T activity (IC50 = 0.35 mg/mL). Extracts from Centella asiatica (gotu kola) and Valeriana officinalis (valerian) stimulated GAD activity by over 40% at a dose of 1 mg/mL. On the other hand, both Matricaria recutita (German chamomile) and Humulus lupulus (hops) showed significant inhibition of GAD activity (0.11-0.65 mg/mL). Several of these species may therefore warrant further pharmacological investigation. The relation between enzyme activity and possible in vivo mode of action is discussed.     

Gender-based differences in physician payments within the fee-for-service system in Ontario: a retrospective,cross-sectional study

Background:Differences in physician income by gender have been described in numerous jurisdictions, but few studies have looked at a Canadian cohort with adjustment for confounders. In this study, we aimed to understand differences in fee-for-service payments to men and women physicians in Ontario.Methods:We conducted a cross-sectional analysis of all Ontario physicians who submitted claims to the Ontario Health Insurance Plan (OHIP) in 2017. For each physician, we gathered demographic information from the College of Physicians and Surgeons of Ontario registry. We compared differences in physician claims between men and women in the entire cohort and within each specialty using multivariable linear regressions, controlling for length of practice, specialty and practice location.Results:We identified a cohort of 30 167 physicians who submitted claims to OHIP in 2017, including 17 992 men and 12 175 women. When controlling for confounding variables in a linear mixed-effects regression model, annual physician claims were $93 930 (95% confidence interval $88 434 to $99 431) higher for men than for women. Women claimed 74% as much as men when adjusting for covariates. This discrepancy was present in nearly all specialty categories. Men claimed more than women throughout their careers, with the greatest gap 10–15 years into practice.Interpretation:We found a gender gap in fee-for-service claims in Ontario, with women claiming less than men overall and in nearly every specialty. Further work is required to understand the root causes of the gender pay gap.

A gender pay gap in physician incomes has been described across numerous jurisdictions.¹ Previous analyses have found income differences between women and men in the general physician population, among academic physicians and among physicians within the same specialty, ^2–8 and when controlling for years of experience, hours worked, geographic location, race and practice type.^9–13Although the difference in physician income between women and men is well described in the United States, fewer studies have looked at a Canadian cohort. An analysis of surgeons in Ontario found that female surgeons earned less per hour spent operating than male surgeons, and suggested that female physicians were more likely to perform less lucrative procedures than male physicians.¹⁴ A recent report released by the Ontario Medical Association highlighted income disparity between men and women physicians in Ontario, but did not provide a detailed breakdown by specialty.¹⁵ Transparent and detailed reporting on gender differences in physician payments can provide data to guide advocacy for greater pay equity.In this study, we aimed to describe payments to physicians across the province of Ontario by gender when controlling for specialty choice, career stage and physician demographics.     

The enteric parasite Entamoeba uses an autocrine catecholamine system during differentiation into the infectious cyst stage.

Enteric amoebae of the genus Entamoeba travel from host to host in an encysted form. We previously showed that in vitro cyst development of Entamoeba invadens requires the addition of defined amounts of multivalent galactose-terminated molecules, such as mucin, to the cultures. The amoeba surface lectin that binds mucin is presumed to convey transmembrane signals when clustered by the ligand, but the signaling molecules that function downstream of the lectin are not known. We report here that Entamoeba encystation was induced in the absence of galactose ligand when catecholamines were added to the encystation medium. Micromolar amounts of both epinephrine and norepinephrine induced encystation. Of a variety of synthetic catecholamine agonists tested, only beta(1)-adrenergic receptor agonists supported encystation, whereas alpha- and beta(2)-adrenergic receptor agonists did not. Only beta(1)-adrenergic receptor antagonists inhibited encystation, and did so even when exogenous catecholamines were not added, indicating that catecholamine binding is required for encystation and suggesting an endogenous source of the ligand. High performance liquid chromatography analysis of Entamoeba extracts showed that the amoebae themselves contain catecholamines and at least one of these is released when the cells are stimulated to encyst with galactose-terminated ligands. The presence of catecholamine binding sites on the surface of amoeba trophozoites was confirmed using radiolabeled catecholamine antagonist. Amoeba encystment was inhibited by addition of beta(1)-adrenergic receptor antagonist to cells that were stimulated to differentiate with either galactose ligand or catecholamines, but not with dibutyryl cAMP. This suggests that the amoeba catecholamine receptor functions downstream of the galactose lectin and upstream of adenylyl cyclase. This enteric protozoan parasite, therefore, contains the components of an autocrine catecholamine ligand-receptor system that may act in conjunction with a galactose lectin to regulate differentiation into the infectious cyst stage.     

Bombesin-like peptides and associated receptors within the brain: distribution and behavioral implications

As we commemorate the 25th anniversary of the journal Peptides, it is timely to review the functional significance of the bombesin (BB)-like peptides and receptors in the CNS. Over two decades ago we published an article in the journal Peptides demonstrating that BB-like peptides are present in high densities in certain rat brain regions (such as the paraventricular nucleus of the hypothalamus). Subsequently, one of the mammalian forms of BB, gastrin-releasing peptide (GRP) containing cell bodies were found in the suprachiasmatic nucleus of the hypothalamus and nucleus of the solitary tract of the hindbrain. Another related peptide, namely neuromedin (NM)B, was detected in the olfactory bulb and dentate gyrus. BB and GRP bind with high affinity to BB(2) receptors, whereas NMB binds with high affinity to BB(1) receptors. The actions of BB or GRP are blocked by BB(2) receptor antagonists such as (Psi(13,14)-Leu(14))BB whereas PD168368 is a BB(1) receptor antagonist. Exogenous administration of BB into the rat brain causes hypothermia, hyperglycemia, grooming and satiety. BB-like peptides activate the sympathetic nervous system and appear to modulate stress, fear and anxiety responses. GRP and NMB modulate distinct biological processes through discrete brain regions or circuits, and globally these peptidergic systems may serve in an integrative or homeostatic function.     

Protracted Effects of Juvenile Stressor Exposure Are Mitigated by Access to Palatable Food

Stressor experiences during the juvenile period may increase vulnerability to anxiety and depressive-like symptoms in adulthood. Stressors may also promote palatable feeding, possibly reflecting a form of self-medication. The current study investigated the short- and long-term consequences of a stressor applied during the juvenile period on anxiety- and depressive-like behavior measured by the elevated plus maze (EPM), social interaction and forced swim test (FST). Furthermore, the effects of stress on caloric intake, preference for a palatable food and indices of metabolic syndrome and obesity were assessed. Male Wistar rats exposed to 3 consecutive days of variable stressors on postnatal days (PD) 27–29, displayed elevated anxiety-like behaviors as adults, which could be attenuated by consumption of a palatable high-fat diet. However, consumption of a palatable food in response to a stressor appeared to contribute to increased adiposity.     

Neuroproteome Changes after Ischemia/Reperfusion Injury and Tissue Plasminogen Activator Administration in Rats: A Quantitative iTRAQ Proteomics Study

The thrombolytic, recombinant tissue plasminogen activator (rt-PA) is the only approved therapy for acute ischemic stroke (AIS). When administered after AIS, rt-PA has many adverse pleiotropic actions, which are currently poorly understood. The identification of proteins showing differential expression after rt-PA administration may provide insight into these pleiotropic actions. In this study we used a 2D-LC MS/MS iTRAQ proteomic analysis, western blotting, and pathway analysis to analyze changes in protein expression 24-hours after rt-PA administration in the cortical brain tissue of 36 rats that underwent a sham or transient middle cerebral artery occlusion surgery. After rt-PA administration we reported alterations in the expressions of 18 proteins, many of which were involved in excitatory neurotransmitter function or cytoskeletal structure. The expression changes of GAD2 and EAAT1 were validated with western blot. The interactions between the identified proteins were analyzed with the IPA pathway analysis tool and three proteins: DPYSL2, RTN4, and the NF-kB complex, were found to have characteristics of being key proteins in the network. The differential protein expressions we observed may reflect pleiotropic actions of rt-PA after experimental stroke, and shine light on the mechanisms of rt-PA''s adverse effects. This may have important implications in clinical settings where thrombolytic therapy is used to treat AIS.