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Oxidative stress (OS) is a common toxic feature in various neurodegenerative diseases. Therefore, reducing OS could provide a potential approach to achieve neuroprotection. Prolyl oligopeptidase (PREP) is a serine protease that is linked to neurodegeneration, as endogenous PREP inhibits autophagy and induces the accumulation of detrimental protein aggregates. As such, inhibition of PREP by a small-molecular inhibitor has provided neuroprotection in preclinical models of neurodegenerative diseases. In addition, PREP inhibition has been shown to reduce production of reactive oxygen species (ROS) and the absence of PREP blocks stress-induced ROS production. However, the mechanism behind PREP-related ROS regulation is not known. As we recently discovered PREP's physiological role as a protein phosphatase 2A (PP2A) regulator, we wanted to characterize PREP inhibition as an approach to reduce OS. We studied the impact of a PREP inhibitor, KYP-2047, on hydrogen peroxide and ferrous chloride induced ROS production and on cellular antioxidant response in HEK-293 and SH-SY5Y cells. In addition, we used HEK-293 and SH-SY5Y PREP knock-out cells to validate the role of PREP on stress-induced ROS production. We were able to show that absence of PREP almost entirely blocks the stress-induced ROS production in both cell lines. Reduced ROS production and smaller antioxidant response was also seen in both cell lines after PREP inhibition by 10 µM KYP-2047. Our results also revealed that the OS reducing mechanism of PREP inhibition is related to reduced activation of ROS producing NADPH oxidase through enhanced PP2A activation. In conclusion, our results suggest that PREP inhibition could also provide neuroprotection by reducing OS, thus broadening the scope of its beneficial effects on neurodegeneration.

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Abnormal protein kinase C (PKC) function contributes to many pathophysiological processes relevant for Alzheimer's disease (AD), such as amyloid precursor protein (APP) processing. Phorbol esters and other PKC activators have been demonstrated to enhance the secretion of soluble APPα (sAPPα), reduce the levels of ß-amyloid (Aß), induce synaptogenesis, and promote neuroprotection. We have previously described isophthalate derivatives as a structurally simple family of PKC activators. Here, we characterised the effects of isophthalate derivatives HMI-1a3 and HMI-1b11 on neuronal viability, neuroinflammatory response, processing of APP and dendritic spine density and morphology in in vitro. HMI-1a3 increased the viability of embryonic primary cortical neurons and decreased the production of the pro-inflammatory mediator TNFα, but not that of nitric oxide, in mouse neuron-BV2 microglia co-cultures upon LPS- and IFN-γ-induced neuroinflammation. Furthermore, both HMI-1a3 and HMI-1b11 increased the levels of sAPPα relative to total sAPP and the ratio of Aß42/Aß40 in human SH-SY5Y neuroblastoma cells. Finally, bryostatin-1, but not HMI-1a3, increased the number of mushroom spines in proportion to total spine density in mature mouse hippocampal neuron cultures. These results suggest that the PKC activator HMI-1a3 exerts neuroprotective functions in the in vitro models relevant for AD by reducing the production of TNFα and increasing the secretion of neuroprotective sAPPα.

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BACKGROUND AND PURPOSE: Orexin receptors potently signal to lipid messenger systems, and our previous studies have suggested that PLD would be one of these. We thus wanted to verify this by direct measurements and clarify the molecular mechanism of the coupling. EXPERIMENTAL APPROACH: Orexin receptor-mediated PLD activation was investigated in CHO cells stably expressing human OX(1) orexin receptors using [(14) C]-oleic acid-prelabelling and the transphosphatidylation assay. KEY RESULTS: Orexin stimulation strongly increased PLD activity - even more so than the phorbol ester TPA (12-O-tetradecanoyl-phorbol-13-acetate), a highly potent activator of PLD. Both orexin and TPA responses were mediated by PLD1. Orexin-A and -B showed approximately 10-fold difference in potency, and the concentration-response curves were biphasic. Using pharmacological inhibitors and activators, both orexin and TPA were shown to signal to PLD1 via the novel PKC isoform, PKCδ. In contrast, pharmacological or molecular biological inhibitors of Rho family proteins RhoA/B/C, cdc42 and Rac did not inhibit the orexin (or the TPA) response, nor did the molecular biological inhibitors of PKD. In addition, neither cAMP elevation, Gα(i/o) nor Gßγ seemed to play an important role in the orexin response. CONCLUSIONS AND IMPLICATIONS: Stimulation of OX(1) receptors potently activates PLD (probably PLD1) in CHO cells and this is mediated by PKCδ but not other PKC isoforms, PKDs or Rho family G-proteins. At present, the physiological significance of orexin-induced PLD activation is unknown, but this is not the first time we have identified PKCδ in orexin signalling, and thus some specific signalling cascade may exist between orexin receptors and PKCδ.

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BACKGROUND: Experience of workplace downsizing (ie reduction in personnel) is common and may constitute a threat to public health in working populations. This study aimed to determine whether downsizing was associated with increased mortality among those remaining in the downsized workplaces. METHODS: Prospective population registration data containing detailed socioeconomic and demographic information on 85 833 Finnish employees aged 35-64 years at the beginning of 1994 or 1993 followed up for cause-specific mortality for 8 years. One-year changes in workplace staffing levels were obtained from Statistics Finland records on workplaces. RESULTS: There was no association between downsizing on any level (a 10-29%, 30-49% or 50-100% reduction in personnel) and increased all-cause mortality among those remaining in the downsized workplaces. No sex differences were observed in these effects among those who remained in the downsized workplaces, nor was a period of particular vulnerability immediately following the downsizing identified. Furthermore, no detrimental effects were observed for any particular cause of death studied. CONCLUSIONS: The results provide evidence that downsizing is not a significant determinant of excess mortality among those remaining in the downsized workplaces.

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AIMS: To study immune deposits in renal glomeruli. METHODS: Tissue was obtained from 756 necropsy cases from people who had committed suicide or met with a violent death. Glomerular immune deposits were examined by immunofluorescence microscopy and a light microscopy. The clinical histories of all the decreased were studied to ascertain reasons for the deposits. RESULTS: Immune deposits were found in glomeruli in 91 (12%) cases. In 52 (6.8%) cases mesangial IgA was observed as a solitary finding in 34 (4.5%), and was accompanied by other immunoglobulins in 18 (2.4%). Mesangial IgM was present in 19 (2.5%) and IgG in 11 cases (1.5%). Two cases had capillary IgG (0.3%). Light microscopic examination showed mesangial enlargement in eight of the cases with mesangial IgA. These included one with IgA glomerulonephritis diagnosed before death. Two cases with normal glomerular morphology and mesangial IgA deposits had clinical laboratory evidence of renal disease. In two subjects with normal glomerular morphology, mesangial IgM and microscopic haematuria were present. In one case with capillary IgG membranous glomerulonephritis was detected. CONCLUSIONS: Ten cases had mesangial IgA together with morphological or clinical laboratory findings suggestive of renal disease. If all these are regarded as IgA glomerulonephritis, then its prevalence can be estimated at 1.3%. For IgM glomerulonephritis, a prevalence of 0.3% was deduced.

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Of the fifty-seven cases of cot death studied two-thirds were younger than 3 months, which is also the peak age of infantile hypoglycaemia. Findings from routine necropsy and histology were scarce; in eleven cases they could be regarded as potentially fatal. About half of the infants had had a mild virus-type infection approximately one week before death. Special attention was paid to endocrine pancreas. Insulitis or lymphocytes in the septa were discovered in twelve cases. Hyperplasia of the islets of Langerhans was a common observation; the hyperplasia being either nesidioblastosis-like with clusters of islets around ducti, or diffuse. The average proportion of islet tissue in the whole pancreas parenchyma was around 5% in infants aged 1--6 months, the percentage being significantly greater than in age-matched controls (4.3%). The pancreatic insulin content was also higher in the cot death cases. Serum insulin values were low (mean 4.8 +/- 1.2 microU/ml) in cot deaths; in the controls they were twice as high (mean 11.6 +/- 1.6 microU/ml) (p less than 0.005). The cause of death in this group of cot deaths could thus be (congenital?) hyperplasia of the islets, possibly combined with a lesion in the B-cells caused by a virus. The mechanism of death would be hypoglycaemia.

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