Organizational antecedents of firms’ adoption of strategic human resource practices: Toward a reconciliation of CEO perceptions and family influence

There is lively debate in the literature about the effects of family influence on employment practices. Particularly, little empirical research explores the role of family influence in driving a firm’s adoption of specific strategic human resource practices such as high-performance work systems. Drawing from the tenets of the resource-based and stewardship theories, this study examines the relationship between chief executive officers’ perceived human resource capability and firm adoption of high-performance work systems in family business, and the joint moderating effect of family management and ownership on the above linkage. Our analysis uses chief executive officer–human resource manager matched samples of 145 Taiwanese publicly listed firms, the results show that chief executive officers perceived human resource capability is significantly and positively associated with the adoption of high-performance work systems. Moreover, this relationship is found to be the strongest when the family assumes leadership in management (i.e. the firm has a family chief executive officer) and family ownership is high.

Family influences in the internationalization of the top 1,000 Taiwanese enterprises

Purpose

This paper aims to investigate the moderating effects of employee commitment, customer loyalty and corporate reputation on the relationship between family influence and international expansion.

Design/methodology/approach

A cross-national research design was conducted using both survey and secondary data of 119 firms taken from the top 1,000 Taiwanese enterprises.

Findings

This study found moderating effects in the positive impact of family influence on international expansion. Specifically, the study found the relationship between family influence and international expansion stronger for companies with greater relational support from employees, customers and the public.

Research limitations/implications

Multi-level data collection and a longitudinal research design in future research could help in further understanding the relationships between the variables in this study.

Practical implications

This paper suggests that family business should establish enduring relationship with their employees and customers and have a plan to improve family reputation that will benefit international market expansion.

Originality/value

This study draws on the relational perspective to investigate how family influence results in different international expansion.

Plasma Translocator Protein Levels and Outcomes of Acute Ischemic Stroke: A Pilot Study

Translocator protein 18 kDa (TSPO) has been used as a biomarker of brain injury and inflammation in various neurological diseases. In this study, we measured the level of TSPO in acute ischemic stroke patients and determined its association with the degree of stroke severity and its ability to predict stroke functional outcomes. In total, 38 patients with moderate to severe acute ischemic stroke were enrolled. Demographic information, cerebral risk factors, and stroke severity were examined at the baseline. The National Institutes of Health Stroke Scale, modified Rankin Scale, and Barthal Index were assessed at discharge as measures of poor functional outcomes and severe disability. The baseline fasting plasma TSPO level was assessed within 24 h after the incident stroke and during hospitalization (on days 8-10). The proportion of patients with poor functional outcomes was significantly higher in the higher-TSPO group (compared to the lower group) in terms of clinical worsening (odds ratio (OR) = 11.69, 95% confidence interval (CI) = 2.08-65.6), poor functional outcomes (OR = 10.5, 95% CI = 1.14-96.57), and severe disability (OR = 4.8, 95% CI = 1.20-19.13). Plasma TSPO may be intimately linked with disease progression and worse functional outcomes in acute ischemic stroke patients.

Calcitriol Inhibits HCV Infection via Blockade of Activation of PPAR and Interference with Endoplasmic Reticulum-Associated Degradation

Vitamin D has been identified as an innate anti-hepatitis C virus (HCV) agent but the possible mechanisms for this issue remain unclear. Here, we clarified the mechanisms of calcitriol-mediated inhibition of HCV infection. Calcitriol partially inhibited HCV infection, nitric oxide (NO) release and lipid accumulation in Huh7.5 human hepatoma cells via the activation of vitamin D receptor (VDR). When cells were pretreated with the activators of peroxisome proliferator-activated receptor (PPAR)-α (Wy14643) and -γ (Ly171883), the calcitriol-mediated HCV suppression was reversed. Otherwise, three individual stimulators of PPAR-α/β/γ blocked the activation of VDR. PPAR-β (linoleic acid) reversed the inhibition of NO release, whereas PPAR-γ (Ly171883) reversed the inhibitions of NO release and lipid accumulation in the presence of calcitriol. The calcitriol-mediated viral suppression, inhibition of NO release and activation of VDR were partially blocked by an inhibitor of endoplasmic reticulum-associated degradation (ERAD), kifunensine. Furthermore, calcitriol blocked the HCV-induced expressions of apolipoprotein J and 78 kDa glucose-regulated protein, which was restored by pretreatment of kifunensine. These results indicated that the calcitriol-mediated HCV suppression was associated with the activation of VDR, interference with ERAD process, as well as blockades of PPAR, lipid accumulation and nitrative stress.

Differential Ca2+ mobilization and mast cell degranulation by FcεRI- and GPCR-mediated signaling

Mast cells play a primary role in allergic diseases. During an allergic reaction, mast cell activation is initiated by cross-linking IgE-FcεRI complex by multivalent antigen resulting in degranulation. Additionally, G protein-coupled receptors also induce degranulation upon activation. However, the spatio-temporal relationship between Ca²⁺ mobilization and mast cell degranulation is not well understood. We investigated the relationship between oscillations in Ca²⁺ level and mast cell degranulation upon stimulation in rat RBL-2H3 cells. Nile red and Fluo-4 were used as probes for monitoring histamine and intracellular Ca²⁺ levels, respectively. Histamine release and Ca²⁺ oscillations in real-time were monitored using total internal reflection fluorescence microscopy (TIRFM). Mast cell degranulation followed immediately after FcεRI and GPCR-mediated Ca²⁺ increase. FcεRI-induced Ca²⁺ increase was higher and more sustained than that induced by GPCRs. However, no significant difference in mast cell degranulation rates was observed. Although intracellular Ca²⁺ release was both necessary and sufficient for mast cell degranulation, extracellular Ca²⁺ influx enhanced the process. Furthermore, cytosolic Ca²⁺ levels and mast cell degranulation were significantly decreased by downregulation of store-operated Ca²⁺ entry (SOCE) via Orai1 knockdown, 2-aminoethyl diphenylborinate (2-APB) or tubastatin A (TSA) treatment. Collectively, this study has demonstrated the role of Ca²⁺ signaling in regulating histamine degranulation.

Lipoprotein lipase liberates free fatty acids to inhibit HCV infection and prevent hepatic lipid accumulation

Lipoprotein lipase (LPL) has been identified as an anti-hepatitis C virus (HCV) host factor, but the cellular mechanism remains elusive. Here, we investigated the cellular mechanism of LPL involving in anti-HCV. The functional activation of peroxisome proliferator-activated receptor (PPAR) α signal by LPL transducing into hepatocytes was investigated in HCV-infected cells, primary human hepatocytes, and in HCV-core transgenic mice. The result showed that the levels of transcriptional transactivity and nuclear translocation of PPARα in Huh7 cells and primary human hepatocytes were elevated by physiologically ranged LPL treatment of either very-low density lipoprotein or HCV particles. The LPL-induced hepatic PPARα activation was weakened by blocking the LPL enzymatic activity, and by preventing the cellular uptake of free unsaturated fatty acids with either albumin chelator or silencing of CD36 translocase. The knockdowns of PPARα and CD36 reversed the LPL-mediated suppression of HCV infection. Furthermore, treatment with LPL, like the direct activation of PPARα, not only reduced the levels of apolipoproteins B, E, and J, which are involved in assembly and release of HCV virions, but also alleviated hepatic lipid accumulation induced by core protein. HCV-core transgenic mice exhibited more hepatic miR-27b, which negatively regulates PPARα expression, than did the wild-type controls. The induction of LPL activity by fasting in the core transgenic mice activated PPARα downstream target genes that are involved in fatty acid β-oxidation. Taken together, our study reveals dual beneficial outcomes of LPL in anti-HCV and anti-steatosis and shed light on the control of chronic hepatitis C in relation to LPL modulators.

High-order micro-ring resonator with perfect transmission using symmetrical Fibonacci structures

A symmetrical Fibonacci micro-ring resonator (SFMR) has been presented to avoid the coupled resonator optical waveguide (CROW) bottle, which is a bottle-shaped distribution for high orders in transmission spectra. The SFMR features three advantages that improve filtering quality compared to that provided by traditional periodic micro-ring resonators. First, sharper resonances are obtained by eliminating the CROW bottle from the mini gaps that appear in the major-band region. Second, peaks with perfect transmission are always obtained without a radius and coupling modulation in the mini-band regions and major-band regions. Third, the full width at half-maximum of the band-edge peak decreases with the increasing generation order.

Sharp resonance with complete transmission in Thue-Morse microring resonators

We present sharp resonances with complete transmission in the Thue-Morse microring resonator. The quasi-periodic structure attains a better quality of filtering than the traditional periodic structure. This includes the following: (i) the high-Q resonances with complete transmission are obtained in the transmission spectra, (ii) the maximum value of transmittance always remains 1 for an arbitrary proportion of two different radiuses in the major-band regions, and (iii) the complete transmission occurs for arbitrary coupling in the mini-band regions. Moreover, we propose an analytical method to predict the occurrences of resonance peaks in the mini-band regions based on the gap map.

Superradiant modes in resonant quasi-periodic double-period quantum wells

This paper firstly proposes the existence of superradiant modes in resonant quasi-periodic double-period quantum wells (QWs), which has not been observed from analyzing the structure factor by traditional methods. Using the gap map method, the reflection spectra under the relevant conditions show that there are dips in the middle and the linewidth grows linearly, despite the dips, as the number of QWs increases, which is a direct demonstration of superradiance. It is also found that the relevant conditions are divided into three regions, each of which has a different width of bandgaps.

Apolipoprotein J, a glucose-upregulated molecular chaperone, stabilizes core and NS5A to promote infectious hepatitis C virus virion production

BACKGROUND & AIMS

Hepatitis C virus (HCV) infection leads to glucose abnormality. HCV depends on lipid droplets (LDs) and very-low density lipoproteins for assembly/releasing; however, the components and locations for this process remain unidentified. Apolipoprotein J (ApoJ), upregulated by glucose, functions as Golgi chaperone of secreted proteins and resides abundantly in very-low density lipoproteins. This study investigates the interplay between glucose, ApoJ and HCV virion production.

METHODS

The effects of high glucose on ApoJ expression and HCV production were evaluated with cultivated HuH7.5, primary human hepatocytes, and in treatment naive chronic hepatitis C patients. How ApoJ affects HCV lifecycle was assessed using siRNA knockdown strategy in JFH1 infected and subgenomic replicon cells. The interactions and locations of ApoJ with viral and host components were examined by immunoprecipitation, immunofluorescence and subcellular fractionation experiments.

RESULTS

HCV infection increased ApoJ expression, which in parallel with HCV infectivity was additionally elevated with high glucose treatment. Serum ApoJ correlated positively with fasting blood glucose concentration and HCV-RNA titre in patients. ApoJ silencing reduced intracellular and extracellular HCV infectivity and extracellular HCV-RNA, but accumulated intracellular HCV-RNA in HCV-infected cells. ApoJ interacted with HCV core and NS5A and stabilized the dual protein complex. HCV infection dispersed cytoplasmic ApoJ from the compact zones of the Golgi to encircle LDs, where co-localization of the core, NS5A, HCV-RNA, subcellular markers for LDs, endoplasmic reticulum (ER), Golgi, and membrane contact sites occurred.

CONCLUSIONS

ApoJ facilitates infectious HCV particle production via stabilization of core/NS5A, which might surround LDs at the ER-Golgi membrane contact site.

Localized modes in one-dimensional symmetric Thue-Morse quasicrystals

We present occurrence of the strongly localized modes with high transmission in one dimensional symmetric Thue-Morse quasicrystals. This quasicrystal has some interesting properties, including (i) there are strongly localized modes in separated regions which are around odd semi-quarter-wave thickness of the system, (ii) both the frequency of localized mode and the thicknesses of the space layer to appear localized modes are variant for different generation orders of the system, and (iii) the sharpness of the resonant peaks in the transmission spectra increases as the generation order of the system increases.

Quasi-Bragg conditions in Thue-Morse dielectric multilayers

The existence of quasi-Bragg conditions (QBCs) in Thue-Morse dielectric multilayers (TMDMs), based on high reflectance and large forbidden gap regions in its transmission spectra, is presented. In contrast to a single traditional Bragg condition (TBC) in periodic bilayers, there are three QBCs in TMDMs. The formula for each of these QBCs is derived. The results show that one of these QBCs just overlaps the TBC. However, a singular point with perfect transmission exists in this QBC at the quarter-wave stack, at which high reflection exists in the periodic bilayers.

Blockade of reactive oxygen species and Akt activation is critical for anti-inflammation and growth inhibition of metformin in phosphatase and tensin homolog-deficient RAW264.7 cells

CONTEXT

Metformin is widely used for treatment of type 2 diabetes and has a potential application on the treatment of inflammation and cancer. Phosphatase and tensin homolog (PTEN) plays a critical role in cancer cell growth and inflammation; however, precise mechanisms remain unclear.

OBJECTIVE

We aimed to investigate the possible mechanisms of how PTEN regulates metformin against cell growth and inflammation.

MATERIALS AND METHODS

We established PTEN knockdown in RAW264.7 murine macrophages (shPTEN cells) to detect inflammatory mediators using commercial kits, production of reactive oxygen species (ROS) by flow cytometry, cell growth by MTT assay and phosphorylated levels of signal molecules by western blot.

RESULTS

The shPTEN cells had a significant large amount of inflammatory mediators, such as inducible nitric oxide synthase (iNOS)/nitric oxide (NO) and cyclooxygenase-2 (COX-2)/prostaglandin E(2) (PGE(2)); and also elevated the production of ROS and increased cell proliferation. These effects were accompanied with the activation of Akt and p38 mitogen-activated protein kinase (MAPK), and the inactivation of an AMP-activated protein kinase (AMPK) activator and extracellular signal-regulated kinase 1/2. Pretreatment with metformin not only blocked these inflammatory mediators, but also caused growth inhibition induced by significant apoptosis. Furthermore, inactivation of Akt, blockade of ROS generation and independence of activations of AMPK and MAPK by metformin were also observed.

CONCLUSION

Macrophages with PTEN deficiency developed a continuous inflammatory microenvironment, which further aggravated tumor cell growth. Moreover, metformin affected PTEN-deficient cells dependent of inhibition of ROS production and Akt activation against enlarged inflammatory mediators and/or cell growth in shPTEN cells.

Glycogen synthase kinase-3β regulates anti-inflammatory property of fluoxetine

A selective serotonin reuptake inhibitor fluoxetine not only is widely used in the treatment of depression but also has an anti-inflammatory property. Glycogen synthase kinase-3beta (GSK-3β) is a vital factor in the inflammation process. How fluoxetine interferes with inflammation via a GSK-3β-dependent pathway remains unclear. The aim of this study is to investigate the effects of fluoxetine on lipopolysaccharide (LPS)-induced inflammation. Results showed that fluoxetine decreased mortality rate of the mice. It also inhibited LPS-induced release of nitric oxide (NO) and prostaglandin E2 (PGE2) in serum and RAW264.7 murine macrophages and expressions of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Upon LPS stimulation, fluoxetine caused a delay but increased in the phosphorylated levels of GSK-3β (ser9), whereas it did not affect LPS-induced activation of mitogen-activated protein kinase (MAPK) and generation of reactive oxygen species (ROS). Fluoxetine in combination with phosphatidylinositol 3-kinases/Akt inhibitors (LY294002 and Wortmannin) did not have a synergistic inhibition on LPS-induced NO release and PGE2 production. In addition, peroxisome proliferator-activated receptor γ (PPARγ) antagonist GW9622 showed no reverse effects of this inhibition of fluoxetine. GSK-3β knockdown blocked the inhibitory effects of fluoxetine on LPS-induced iNOS/NO release and COX-2/PGE2 production. These results indicated that GSK-3β regulated anti-inflammatory property of fluoxetine. However, Akt activation, ROS generation, and altered PPARγ activity were not involved in this inhibition of fluoxetine.

Glucosylceramide synthase inhibitor PDMP sensitizes chronic myeloid leukemia T315I mutant to Bcr-Abl inhibitor and cooperatively induces glycogen synthase kinase-3-regulated apoptosis

Inactivation of glycogen synthase kinase (GSK)-3 has been implicated in cancer progression. Previously, we showed an abundance of inactive GSK-3 in the human chronic myeloid leukemia (CML) cell line. CML is a hematopoietic malignancy caused by an oncogenic Bcr-Abl tyrosine kinase. In Bcr-Abl signaling, the role of GSK-3 is not well defined. Here, we report that enforced expression of constitutively active GSK-3 reduced proliferation and increased Bcr-Abl inhibition-induced apoptosis by nearly 1-fold. Bcr-Abl inhibition activated GSK-3 and GSK-3-dependent apoptosis. Inactivation of GSK-3 by Bcr-Abl activity is, therefore, confirmed. To reactivate GSK-3, we used glucosylceramide synthase (GCS) inhibitor PDMP to accumulate endogenous ceramide, a tumor-suppressor sphingolipid and a potent GSK-3 activator. We found that either PDMP or silence of GCS increased Bcr-Abl inhibition-induced GSK-3 activation and apoptosis. Furthermore, PDMP sensitized the most clinical problematic drug-resistant CML T315I mutant to Bcr-Abl inhibitor GNF-2-, imatinib-, or nilotinib-induced apoptosis by >5-fold. Combining PDMP and GNF-2 eliminated transplanted-CML-T315I-mutants in vivo and dose dependently sensitized primary cells from CML T315I patients to GNF-2-induced proliferation inhibition and apoptosis. The synergistic efficacy was Bcr-Abl restricted and correlated to increased intracellular ceramide levels and acted through GSK-3-mediated apoptosis. This study suggests a feasible novel anti-CML strategy by accumulating endogenous ceramide to reactivate GSK-3 and abrogate drug resistance.

Dermatophagoides pteronyssinus 2 regulates nerve growth factor release to induce airway inflammation via a reactive oxygen species-dependent pathway

Group 2 allergen of Dermatophagoides pteronyssinus 2 (Der p2) induces airway inflammation without protease activity, and elevated nerve growth factor (NGF) levels are also found in this inflammation. How the allergen Der p2 regulates NGF release via reactive oxygen species (ROS) to induce inflammation remains unclear. In the present study, intratracheal administration of Der p2 to mice led to inflammatory cell infiltration, mucus gland hyperplasia, and NGF upregulation in the bronchial epithelium, as well as elevated ROS and NGF production in bronchoalveolar lavage fluids. In addition, Der p2 caused fibrocyte accumulation and mild fibrosis. p38 mitogen-activated protein kinase (MAPK) and c-Jun N-terminal kinase (JNK) inhibitors inhibited Der p2-induced NGF release in LA4 lung epithelial cells and MLg lung fibroblasts. Pretreatment with an antioxidant, tiron, reduced the Der p2-induced ROS production, NGF expression and release, p38 MAPK or JNK phosphorylation, and airway inflammation. These results suggest that Der p2 allergen-induced airway inflammation and elevated NGF release were through increasing ROS production and a MAPK-dependent pathway. The use of an antioxidant, tiron, may provide a new therapeutic modality for the treatment of allergic asthma.

Activation of imidazoline I2B receptors is linked with AMP kinase pathway to increase glucose uptake in cultured C2C12 cells

Guanidine, the active ingredient extracted from Galega officinalis, is introduced as a ligand for imidazoline I2 receptor (I2R) because guanidine decreased plasma glucose via an activation of I2BR to increase glucose uptake into skeletal muscle isolated from Wistar rats. However, the signals for this action of guanidine remained obscure. In the present study, we used the cultured skeletal muscle fibroblast named C2C12 cell line to investigate this point. We found that guanidine increased the phosphorylation of AMP-activated protein kinase (AMPK) in addition to the higher of glucose transporter GLUT4 expression and glucose uptake. These effects of guanidine were blocked by the pretreatment with I2R antagonist BU224 but not by the blockade of I2AR amiloride. Moreover, compound C at concentrations sufficient to inhibit AMPK blocked the guanidine-induced glucose uptake and GLUT4 protein level. These results suggested that guanidine increases glucose uptake via an activation of I2BR through AMPK activation in skeletal muscle cell; this view has not been mentioned before.

High-pressure needle interface for thermoplastic microfluidics

A robust and low dead volume world-to-chip interface for thermoplastic microfluidics has been developed. The high pressure fluidic port employs a stainless steel needle inserted into a mating hole aligned to an embedded microchannel, with an interference fit used to increase pressure resistance. Alternately, a self-tapping threaded needle screwed into a mating hole is also demonstrated. In both cases, the flat bottom needle ports seat directly against the microchannel substrate, ensuring low interfacial dead volumes. Low dispersion is observed for dye bands passing the interfaces. The needle ports offer sufficient pull-out forces for applications such as liquid chromatography that require high internal fluid pressures, with the epoxy-free interfaces compatible with internal microchannel pressures above 40 MPa.

Changes of dopamine content and cell proliferation by dexamethsone via pituitary adenylate cyclase-activating polypeptide in PC12 cell

Pituitary adenylate cyclase-activating polypeptide (PACAP) is an endogenous neuropeptide observed in adrenal gland and sympathetic ganglia to regulate catecholamine synthesis and release. Both PACAP and glucocorticoid showed the activity to elevate catecholamine level through the stimulation of biosynthesis. However, the relationship of glucocorticoid and PACAP for this action is still unclear. Thus, alterations of gene expression, dopamine (DA) content, and cell proliferation in rat pheochromocytoma PC12 cells are employed as indicators to clarify this relationship in the present study. From the analysis of RT-PCR, the mRNA level of PACAP was observed to be raised by dexamethasone (DEX) and this action was blocked in cells treated with RU486 (mifepristone), a glucocorticoid receptor (GR) antagonist, or actinomycin D, a transcriptional inhibitor. An increase of DA content by HPLC analysis and/or cell proliferation identified by MTT assay by DEX was also observed which could be inhibited by PACAP (6-38) at concentration sufficient to block PACAP type 1 (PAC1) receptor. These results suggest that PACAP is involved in DEX-induced DA biosynthesis and cell proliferation in PC12 cells.

Low temperature bonding of PMMA and COC microfluidic substrates using UV/ozone surface treatment

The use of UV/ozone surface treatments for achieving low temperature bonds between PMMA and COC microfluidic substrates is evaluated. Low temperature bond strengths, approaching those of native polymer substrates bonded above their glass transition temperatures, are demonstrated for both thermoplastics. To evaluate the effects of the UV/O(3) surface treatment on the operation of bonded microfluidic devices, the relationship between UV/O(3) exposure and polymer hydrophilicity and surface chemistry are measured. Post-treatment surface chemistry is evaluated by XPS (X-ray photoelectron spectroscopy) analysis, and the stability of the treated surfaces following solvent exposure is reported. Electroosmotic flow within fabricated microchannels with modified wall surfaces is also characterized. Overall, UV/O(3) treatment is found to enable strong low temperature bonds between thermoplastic microfluidic substrates using a simple, low cost, and high throughput fabrication technology.

Cytokines and serotonin transporter in patients with major depression

Altered cytokine secretion as a mechanism in the etiology of depression is still obscure. The serotonin transporter (5-HTT) may play an important role in the termination of serotonergic neurotransmission by serotonin (5-HT) uptaking into presynaptic neurons and representing as an initial action site for selective 5-HTT reuptake inhibitors (SSRI). In our study, we evaluated whether cytokines and 5-HTT acted as biological markers for depression. Blood samples were collected from 42 participants. The differences in cytokine and 5-HTT mRNA expressions of leukocytes were assessed between the patients with major depression (n=20) and the healthy controls (n=22), along with the measurements prior and after treatment with a SSRI, fluoxetine, for 3 months in the follow-up patient group (n=8). The results revealed that the mRNA expressions of IL-1beta, IL-6, IFNgamma, TNFalpha, and 5-HTT were higher in the depressed patients than those of the healthy controls. The higher level of mRNA expressions of IFNgamma and 5-HTT diminished after fluoxetine treatment. Furthermore, we found a positive correlation between 5-HTT and cytokines mRNA expressions in total participants, which suggested that pro-inflammatory cytokines and 5-HTT might play critical roles in the pathogenesis of major depression and that their levels were affected by chronic treatment with 5-HTT inhibitors.

Down-regulation of Bcl-2, activation of caspases, and involvement of reactive oxygen species in 6-hydroxydopamine-induced thymocyte apoptosis

OBJECTIVE

Our previous work showed that 6-hydroxydopamine (6-OHDA) induced mouse thymocytes to undergo apoptosis both in vivo and in vitro. In the present study, we further investigated the mechanisms of 6-OHDA-induced apoptosis in vitro.

METHODS

Naive mouse thymocytes were cultured with 6-OHDA. The percentages of apoptotic cells were quantified by propidium iodide staining, and DNA fragmentation was detected by agarose gel electrophoresis. Intracellular Bcl-2 was analyzed by immunofluorescence staining. Cu/Zn superoxide dismutase (Cu/Zn-SOD) activities were measured by the SOD-525 method.

RESULTS

The apoptotic effect of 6-OHDA was blocked by desipramine, a catecholamine uptake blocker. Treatment with 6-OHDA caused a reduction in Bcl-2 expression. VAD-FMK, a broad-spectrum caspase inhibitor, and DEVD-CHO, a potent inhibitor of caspase-3, could block 6-OHDA-induced thymocyte apoptosis. However, the specific caspase-1 (ICE) inhibitor YVAD-CMK had no effect. This cell death process was prevented by the protein synthesis inhibitor cycloheximide and by antioxidants. The level of Cu/Zn-SOD activities also decreased after cells were exposed to 6-OHDA.

CONCLUSION

These results suggest an apoptotic effect of 6-OHDA via the uptake of this neurotoxin by thymocytes, and that down-regulation of Bcl-2, activation of caspases, such as caspase-3 but not caspase-1, generation of reactive oxygen species, and new synthesis of proteins are involved in this process.

Determinations of morin, quercetin and their conjugate metabolites in serum

Morin and quercetin are isomeric antioxidant flavonols. High-performance liquid chromatographic methods were developed for the quantitation of morin and quercetin in serum. The method employed a Cosmosil RP-18 column, using acetonitrile/0.2% o-phosphoric acid 28/72 and 27/73 (v/v) as mobile phases, with ethyl paraben and 6,7-dimethoxycoumarin used as internal standards for morin and quercetin, respectively. Moreover, a strategy to stabilize morin/quercetin released from their glucuronides/sulfates in serum during hydrolysis was established. The present methods are applicable for determining morin, quercetin, and their glucuronides/sulfates in serum.

Acute intoxication of cyclosporin caused by coadministration of decoctions of the fruits of Citrus aurantium and the Pericarps of Citrus grandis

In order to investigate the effects of Citrus herbs on cyclosporin absorption and disposition, swine were given cyclosporin (10 mg/kg) with or without decoctions of Citri Aurantii Fructus (CAF) or Citri Grandis Pericarpium (CGP) in a crossover design. FPIA method (fluorescence polarization immunoassay) was used to determine the blood concentration of cyclosporin. The decoctions were characterized by their flavanone contents. Our results indicated that the coadministration of CAF and CGP significantly increased the Cmax of cyclosporin by 64% and 79%, respectively. The AUC of cyclosporin was significantly elevated by 97% when coadministered with CGP. Among the swine, 1/5 and 3/5 exhibited acute toxicity of cyclosporin after concomitant intake of CAF and CGP, respectively. This indicates an interaction of Citrus compounds with a commonly used drug. We suggest when cyclosporin is coadministered with these Citrus decoctions, the blood concentration of cyclosporin should be carefully monitored for dose adjustment to avoid cyclosporin intoxication.

Inhibition of immune cell proliferation with haloperidol and relationship of tyrosine hydroxylase expression to immune cell growth

Previous studies indicated that exogenous dopamine and its agonists directly regulated mitogen-induced immune cell proliferation. In this study, we further investigated role of endogenous dopamine in immune cell growth. Haloperidol, a general antagonist for dopamine receptors, could reduce the cell growth rate of T cell hybridoma (10I) and rat nervous pheochromocytoma cells (PC12). Tyrosine hydroxylase (TH) catalyzes the initial rate-limiting step of catecholamine biosynthesis in the nervous system. Flow cytometric analysis indicated the expression of TH in various immune cells. The presence of TH in PC12 cells was used as a control. Temporal studies indicated that the expression of TH increased during 10I cell growth. Both alpha-methyl-p-tyrosine and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine reduced TH expression and cell growth in a dose-dependent manner. These results suggest that immune T cells express TH which is correlated to cell growth, and that dopamine released from these cells may bind to the receptors to act in an autocrine or paracrine way.

Effect of dopamine on immune cell proliferation in mice

Dopamine is known as a precursor of catecholamine and one of the neurotransmitters in brain and peripheral tissues. Recent studies suggest an important role of dopamine in immune responses. In the present study, intraperitoneal administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) which lowered endogenous dopamine suppressed splenocyte proliferation in response to mitogens such as lipopolysaccharide (LPS) and concanavalin A (Con A). Moreover, intravenous injection of the specific agonists of dopamine DA-1 receptor (SKF38393) or DA-2 receptor (LY171555) into mice enhanced the splenocyte proliferation stimulated by LPS or Con A. In the in vitro cultures, dopamine, SKF38393 and LY171555 directly promoted cell proliferation to LPS or Con A. These results indicate that dopamine has an ability to regulate B- and T-cell proliferation both in vivo and in vitro.

The in vitro antioxidant activity of trilinolein and other lipid-related natural substances as measured by enhanced chemiluminescence

There is abundant evidence for the premise that oxygen-derived free radicals (OFR) mediate ischemia/reperfusion injury to the myocardium. OFR scavengers such as superoxide dismutase can effectively reduce damage through lipid peroxidation during ischemia/reperfusion. Enhanced chemiluminescence, which has been used to measure OFR, was used to measure the antioxidant activity of fatty acids (palmitic and linoleic acid) and triglycerides (triolein, tristearin) and natural plant antioxidants (magnolol, catechin, trilinolein). Trilinolein, which has recently been isolated from natural products, as well as the well-known water soluble analogue of vitamin E-Trolox, were used as control. During pretreatment with chemicals, at concentrations of 10(-9) to 10(-7) M, enhanced chemiluminescence of linoleic acid (C 18:2) showed a dose-responsive reduction of OFR with a maximal mean reduction of -31.9% when compared to baseline. A saturated fatty acid such as palmitic acid (C 16:0) showed only relatively weak antioxidant activity at concentrations of 10(-7) to 10(-6) M with a maximum reduction of OFR of- 15.2% only. control chemicals such as trilinolein and Trolox showed significant antioxidant activity. At concentrations between 10(-10) and 10(-6) M and trilinolein has the most potent antioxidant activity with a maximal mean reduction of OFR of -48.0%, whereas Trolox showed only -39.2%. As for the natural plant antioxidants, only catechin showed potent antioxidant activity (-40%). Polyunsaturated triglycerides such as triolein (oleic acid, C 18:1) also possess significant OFR scavenging effect (-31.9%) whilst saturated triglycerides such as tristearin (stearic acid, C 18:0) had only relatively weak antioxidant activity (-15.2%). Generally, the antioxidant activity of unsaturated compounds is stronger than saturated compounds; double-bond existence may partially explain this phenomenon.

6-Hydroxydopamine induces thymocyte apoptosis in mice

6-Hydroxydopamine (6-OHDA) induces degeneration of noradrenergic nerves and has been shown to alter the immune responses. In this study, intraperitoneal administration of 6-OHDA induces mouse thymus atrophy. The lowest levels of thymus weight and cell number were reached at days 3 and 5 in mice receiving 6-OHDA treatment; they gradually recovered thereafter. On flow cytometry analysis, the most substantial reductions were recorded for CD4+CD8+ thymocytes, although the numbers of other subpopulations, i.e. CD4+CD8-, CD4-CD8+ and CD4-CD8- cells were also reduced. DNA fragmentation, a characteristic of apoptosis, was detected in the thymocytes following 6-OHDA injection. Pretreatment with desipramine greatly blocked the reduction in thymus size and thymocyte number, the changes in thymocyte subpopulations, the percentage of subdiploid (apoptotic) cells and the appearance of DNA fragmented bands. Furthermore, 6-OHDA-induced thymocyte apoptosis could also be detected in vitro, and was blocked by desipramine treatment. These results indicate that 6-OHDA induces mouse thymocytes to undergo apoptosis both in vivo and in vitro, and this effect is inhibited by catecholamine uptake blocker.

Trilinolein preserves mitochondria ultrastructure in isolated rat heart subjected to global ischemia through antioxidant activity as measured by chemiluminescence

Oxygen-derived free radicals (OFR) have been proposed as the cause of myocardial damage through lipid peroxidation during ischemia and reperfusion. Antioxidants can effectively ameliorate the damage induced by lipid peroxidation. Trilinolein is a triacylglycerol recently purified from the well known traditional Chinese herb Panax pseudoginseng, which has been used in treating circulatory disorders among Chinese for hundreds of years; it has linoleate as the only fatty acid residue in all three esterified positions of glycerol. This chemical has recently been demonstrated to have antioxidant activity by enhanced chemiluminescence. The addition of phorbol myristic acetate (PMA) to medium containing leukocytes produces OFR; this phenomenon was measured by chemiluminescence. Addition of trilinolein to medium containing leukocytes preceding the addition of PMA suppressed the production of OFR. The control value of chemiluminescence of a medium containing leukocytes with addition of PMA was 9.23 +/- 1.19 x 10(3) mV. The most effective concentration of trilinolein was 10(-7) mol/l which decreased the signals to 4.59 +/- 0.02 x 10(3) mV (p < 0.001). The antioxidant effect had a concentration-response curve similar to alpha-tocopherol. After pretreatment for 15 min with trilinolein at a concentration of 10(-7) mol/l in isolated perfused rat heart which had been subjected to 60 min of global ischemia, the integrity of the rat heart mitochondria was preserved as examined under the electron microscope. No swelling of mitochondria occurred and there was good alignment of cristae and absence of amorphous density. Previous experiments have shown that trilinolein can also improve erythrocyte deformability in vitro. Infarct size reduction of about 50% was also demonstrated in in vivo rat heart subjected to 4 h coronary occlusion. The mechanism of myocardial protection, in addition to the antioxidant effect, is suggested as maintaining the membrane fluidity of cardiomyocytes.