Antitumor Effects of Vitamin D Analogs on Hamster and Mouse Melanoma Cell Lines in Relation to Melanin Pigmentation

Deregulated melanogenesis is involved in melanomagenesis and melanoma progression and resistance to therapy. Vitamin D analogs have anti-melanoma activity. While the hypercalcaemic effect of the active form of Vitamin D (1,25(OH)₂D₃) limits its therapeutic use, novel Vitamin D analogs with a modified side chain demonstrate low calcaemic activity. We therefore examined the effect of secosteroidal analogs, both classic (1,25(OH)₂D₃ and 25(OH)D₃), and novel relatively non-calcemic ones (20(OH)D₃, calcipotriol, 21(OH)pD, pD and 20(OH)pL), on proliferation, colony formation in monolayer and soft-agar, and mRNA and protein expression by melanoma cells. Murine B16-F10 and hamster Bomirski Ab cell lines were shown to be effective models to study how melanogenesis affects anti-melanoma treatment. Novel Vitamin D analogs with a short side-chain and lumisterol-like 20(OH)pL efficiently inhibited rodent melanoma growth. Moderate pigmentation sensitized rodent melanoma cells towards Vitamin D analogs, and altered expression of key genes involved in Vitamin D signaling, which was opposite to the effect on heavily pigmented cells. Interestingly, melanogenesis inhibited ligand-induced Vitamin D receptor translocation and ligand-induced expression of VDR and CYP24A1 genes. These findings indicate that melanogenesis can affect the anti-melanoma activity of Vitamin D analogs in a complex manner.     

Electron transfer to cytochrome P-450scc limits cholesterol-side-chain-cleavage activity in the human placenta

The aim of this study was to determine whether electron transfer from adrenodoxin reductase and adrenodoxin limits the activity of cytochrome P-450scc in mitochondria from the human placenta. Mitochondria were disrupted by sonication to enable exogenous adrenodoxin and adrenodoxin reductase to deliver electrons to cytochrome P-450scc. After sonication, the rate of pregnenolone synthesis was greatly decreased relative to that by intact mitochondria, due to dilution of endogenous adrenodoxin and adrenodoxin reductase into the incubation medium. The addition of saturating concentrations of bovine or human adrenodoxin and bovine adrenodoxin reductase to the disrupted mitochondria gave an initial rate of pregnenolone synthesis that was 6.3-fold higher than that for intact mitochondria. Similar results were observed when 20alpha-hydroxycholesterol was used as substrate rather than endogenous cholesterol. The turnover number of cytochrome P-450scc in sonicated placental mitochondria supplemented with adrenodoxin and adrenodoxin reductase was comparable to that for the purified enzyme assayed under conditions where electron transfer was not limiting. Addition of exogenous adrenodoxin and adrenodoxin reductase to sonicated mitochondria from the pig corpus luteum and rat adrenal had a much smaller effect on pregnenolone synthesis compared with intact mitochondria, than observed for the placenta. We conclude that in the human placenta, electron transfer to cytochrome P-450scc is limiting, permitting pregnenolone synthesis to proceed at only 16% maximum velocity.     

Psychosocial safety climate moderates the job demand–resource interaction in predicting workgroup distress

Psychosocial safety climate (PSC) arises from workplace policies, practices, and procedures for the protection of worker psychological health and safety that are largely driven by management. Many work stress theories are based on the fundamental interaction hypothesis – that a high level of job demands (D) will lead to psychological distress and that this relationship will be offset when there are high job resources (R). However we proposed that this interaction really depends on the organizational context; in particular high levels of psychosocial safety climate will enable the safe utilization of resources to reduce demands. The study sample consisted of police constables from 23 police units (stations) with longitudinal survey responses at two time points separated by 14 months (Time 1, N = 319, Time 2, N = 139). We used hierarchical linear modeling to assess the effect of the proposed three-way interaction term (PSC × D × R) on change in workgroup distress variance over time. Specifically we confirmed the interaction between emotional demands and emotional resources (assessed at the individual level), in the context of unit psychosocial safety climate (aggregated individual data). As predicted, high emotional resources moderated the positive relationship between emotional demands and change in workgroup distress but only when there were high levels of unit psychosocial safety climate. Results were confirmed using a split-sample analysis. Results support psychosocial safety climate as a property of the organization and a target for higher order controls for reducing work stress. The ‘right’ climate enables resources to do their job.     

Modulation by 17,20S(OH)2pD of Fibrosis-Related Mediators in Dermal Fibroblast Lines from Healthy Donors and from Patients with Systemic Sclerosis

We previously demonstrated that the non-calcemic pregnacalciferol (pD) analog 17,20S (OH)₂pD suppressed TGF-β1-induced type I collagen production in cultured normal human dermal fibroblasts. In the present studies, we examined fibroblasts cultured from the lesional skin of patients with systemic sclerosis (scleroderma (SSc)) and assessed the effects of 17,20S(OH)₂pD on fibrosis-related mediators. Dermal fibroblast lines were established from skin biopsies from patients with SSc and healthy controls. Fibroblasts were cultured with either 17,20S(OH)₂pD or 1,25(OH)₂D₃ (positive control) with/without TGF-β1 stimulation and extracted for protein and/or mRNA for collagen synthesis and mediators of fibrosis (MMP-1, TIMP-1, PAI-1, BMP-7, PGES, GLI1, and GLI2). 1 7,20S(OH)₂pD (similar to 1,25(OH)₂D₃) significantly suppressed net total collagen production in TGF-β1-stimulated normal donor fibroblast cultures and in cultures of SSc dermal fibroblasts. 17,20S(OH)₂pD (similar to 1,25(OH)₂D₃) also increased MMP-1, BMP-7, and PGES and decreased TIMP-1 and PAI1 expression in SSc fibroblasts. Although 17,20S(OH)₂pD had no effect on Gli1 or Gli2 in SSc fibroblasts, it increased Gli2 expression when cultured with TGF-β1 in normal fibroblasts. These studies demonstrated that 17,20S(OH)₂pD modulates mediators of fibrosis to favor the reduction of fibrosis and may offer new noncalcemic secosteroidal therapeutic approaches for treating SSc and fibrosis.     

Hydroxylumisterols,Photoproducts of Pre-Vitamin D3, Protect Human Keratinocytes against UVB-Induced Damage

Lumisterol (L3) is a stereoisomer of 7-dehydrocholesterol and is produced through the photochemical transformation of 7-dehydrocholesteol induced by high doses of UVB. L3 is enzymatically hydroxylated by CYP11A1, producing 20(OH)L3, 22(OH)L3, 20,22(OH)2L3, and 24(OH)L3. Hydroxylumisterols function as reverse agonists of the retinoic acid-related orphan receptors α and γ (RORα/γ) and can interact with the non-genomic binding site of the vitamin D receptor (VDR). These intracellular receptors are mediators of photoprotection and anti-inflammatory activity. In this study, we show that L3-hydroxyderivatives significantly increase the expression of VDR at the mRNA and protein levels in keratinocytes, both non-irradiated and after UVB irradiation. L3-hydroxyderivatives also altered mRNA and protein levels for RORα/γ in non-irradiated cells, while the expression was significantly decreased in UVB-irradiated cells. In UVB-irradiated keratinocytes, L3-hydroxyderivatives inhibited nuclear translocation of NFκB p65 by enhancing levels of IκBα in the cytosol. This anti-inflammatory activity mediated by L3-hydroxyderivatives through suppression of NFκB signaling resulted in the inhibition of the expression of UVB-induced inflammatory cytokines, including IL-17, IFN-γ, and TNF-α. The L3-hydroxyderivatives promoted differentiation of UVB-irradiated keratinocytes as determined from upregulation of the expression at the mRNA of involucrin (IVL), filaggrine (FLG), and keratin 14 (KRT14), downregulation of transglutaminase 1 (TGM1), keratins including KRT1, and KRT10, and stimulation of ILV expression at the protein level. We conclude that CYP11A1-derived hydroxylumisterols are promising photoprotective agents capable of suppressing UVB-induced inflammatory responses and restoring epidermal function through targeting the VDR and RORs.     

A comparison between the Macintosh and the McCoy laryngoscope blades

The view of the larynx using the Macintosh laryngoscope and the McCoy levering laryngoscope was assessed in 177 adult patients. The view with the McCoy blade in the neutral position and in the position (neutral or elevated) that gave the 'best' view were recorded. The McCoy blade in the neutral position was associated with a lower incidence of grade 1 views and a higher incidence of grade 2 views than the Macintosh blade. There was no difference in the incidence of grade 3 views. When views for each patient using the different blades were compared, the McCoy blade in the neutral position produced a worse view than the Macintosh blade (p < 0.0001). The view obtained with the McCoy blade in its 'best' position and the Macintosh blade were similar. In the 152 patients in whom the vocal cords were seen using the Macintosh blade, the view was worse using the McCoy blade in its 'best' position more often than it was better (p = 0.06). In 25 patients, the vocal cords could not be seen with the Macintosh blade; in these patients the view was better with the McCoy blade (the cords were visible) on 14 occasions and worse in one (p = 0.001). We conclude that the McCoy blade in its neutral position does not behave identically to the Macintosh blade. The McCoy blade is a useful aid to difficult intubation but should not replace the Macintosh blade as the first choice laryngoscope.     

A rapid and simple fluorometric method for quantifying isoeugenol in seawater and in plasma and white muscle from Australasian snapper (Pagrus auratus)

Isoeugenol residues in Australasian snapper (Pagrus auratus) white muscle, blood plasma and seawater were accurately and precisely quantified after extraction with acetonitrile using fluorometric detection (ex. 260 nm, em. 340 nm) without chromatographic separation. Isoeugenol residues in Australasian snapper (P. auratus) muscle tissue following 30 min exposure to 58.2 μmol L⁻¹ isoeugenol (ca. 20 ppm of the aquatic anaesthetic AQUI-S™) reached a maximum of 134.37 ± 8.13 μmol kg⁻¹ (±SEM; n = 6). Blood plasma isoeugenol concentrations following this harvesting regime were 253.2 ± 25.1 μmol L⁻¹. After 7 h recovery, fillet isoeugenol residues reduced to 7.89 ± 1.67 μmol kg⁻¹. Storage of fillets from fish harvested with AQUI-S™ at 3.87 ± 0.54 °C for 5 days resulted in a rate of isoeugenol decay in the fillets of 6.51 ± 1.19 μmol kg⁻¹ day⁻¹. The method reported can be used for measuring isoeugenol residues in food products or to further study the physiological and biological effects of isoeugenol in fish.     

Psychosocial safety climate as a lead indicator of workplace bullying and harassment, job resources, psychological health and employee engagement

Psychosocial safety climate (PSC) is defined as shared perceptions of organizational policies, practices and procedures for the protection of worker psychological health and safety, that stem largely from management practices. PSC theory extends the Job Demands–Resources (JD-R) framework and proposes that organizational level PSC determines work conditions and subsequently, psychological health problems and work engagement. Our sample was derived from the Australian Workplace Barometer project and comprised 30 organizations, and 220 employees. As expected, hierarchical linear modeling showed that organizational PSC was negatively associated with workplace bullying and harassment (demands) and in turn psychological health problems (health impairment path). PSC was also positively associated with work rewards (resources) and in turn work engagement (motivational path). Accordingly, we found that PSC triggered both the health impairment and motivational pathways, thus justifying extending the JD-R model in a multilevel way. Further we found that PSC, as an organization-based resource, moderated the positive relationship between bullying/harassment and psychological health problems, and the negative relationship between bullying/harassment and engagement. The findings provide evidence for a multilevel model of PSC as a lead indicator of workplace psychosocial hazards (high demands, low resources), psychological health and employee engagement, and as a potential moderator of psychosocial hazard effects. PSC is therefore an efficient target for primary and secondary intervention.     

Effects of Rested Harvesting on Muscle Metabolite Concentrations and K-Values in Chinook Salmon (Oncorhynchus tshawytscha) Fillets during Storage at 15 °C

Abstract: Improvement of harvesting procedures in aquaculture may also improve the quality and storage properties of the fish. The use of an anesthetic allows fish to be harvested with reduced stress and exhaustion, which affect fillet properties. We report here on the effects of rested harvesting on the postharvest metabolic profiles and K-values in Chinook salmon (Oncorhynchus tshawytscha) fillets stored near to the fish's acclimation temperature at 15 °C for 36 h. Fresh rested fillets were obtained by anesthesia with AQUI-S™. They had high cut surface pHs (7.63) and high concentrations of adenosine triphosphate (ATP) and creatine phosphate (3.75 and 8.73 μmol g⁻¹ respectively), which depleted over 12 h. In contrast, fresh exhausted fillets had low cut surface pHs (6.66) and ATP and creatine phosphate were depleted. Adenosine diphosphate (ADP) and β-nicotinamide adenine dinucleotide (NAD⁺) concentrations also remained significantly higher during the first 12 h of storage in rested fillets. In fresh rested fillets inosine monophosphate (IMP) concentrations reached maximum after 12 h storage (4.78 μmol g⁻¹), whereas maximum IMP concentrations occurred immediately postharvest in the exhausted fillets (6.42 μmol g⁻¹). After 36 h storage, K-values in exhausted fillets reached 52.11% compared to 19.27% in rested fillets. Rested harvesting of Chinook salmon improved the fillets’ metabolic potential postharvest, extending metabolite depletion times, changing IMP concentrations and reducing K-values. Practical Application: This study shows that an improved metabolic potential is maintained in salmon fillets from fish harvested in a rested state (that is, with no stress and exhaustion) using an isoeugenol based anesthetic (AQUI-S™). Improved understanding of postharvest metabolic function may help to improve quality and storage properties of high value fish tissues.     

Workplace bullying: The role of psychosocial work environment factors.

Utilizing reports from both observers and direct targets, the authors examined the role of psychosocial work environment factors in workplace bullying, focusing on the moderating effects of control and support resources against job demands. Our sample was 716 Australian frontline police officers who completed an anonymous mail survey. In a direct test of Job Demand-Control-Support theory, the authors found that increased levels of bullying (as assessed by targets and observers) were associated with potentially high stress situations: as job demands increased and as support and control resources decreased. Also, consistent with previous research, most perpetrators were ranked higher than the target, reflecting the role of power in facilitating bullying. Our research is unique in finding evidence for moderating factors within the psychosocial environment and suggests risk assessment of the work environment as an avenue for bullying prevention. Future research should examine more closely the mechanisms underlying bullying within stressful work environments and the reciprocal effect of witnessing and experiencing bullying on psychosocial working conditions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)