Performance of the new biological small- and wide-angle X-ray scattering beamline 13A at the Taiwan Photon Source.

Recent developments in the instrumentation and data analysis of synchrotron small-angle X-ray scattering (SAXS) on biomolecules in solution have made biological SAXS (BioSAXS) a mature and popular tool in structural biology. This article reports on an advanced endstation developed at beamline 13A of the 3.0 GeV Taiwan Photon Source for biological small- and wide-angle X-ray scattering (SAXS-WAXS or SWAXS). The endstation features an in-vacuum SWAXS detection system comprising two mobile area detectors (Eiger X 9M/1M) and an online size-exclusion chromatography system incorporating several optical probes including a UV-Vis absorption spectrometer and refractometer. The instrumentation and automation allow simultaneous SAXS-WAXS data collection and data reduction for high-throughput biomolecular conformation and composition determinations. The performance of the endstation is illustrated with the SWAXS data collected for several model proteins in solution, covering a scattering vector magnitude q across three orders of magnitude. The crystal-model fittings to the data in the q range ∼0.005-2.0 Å-1 indicate high similarity of the solution structures of the proteins to their crystalline forms, except for some subtle hydration-dependent local details. These results open up new horizons of SWAXS in studying correlated local and global structures of biomolecules in solution.

Optical design and performance of the biological small-angle X-ray scattering beamline at the Taiwan Photon Source.

The optical design and performance of the recently opened 13A biological small-angle X-ray scattering (SAXS) beamline at the 3.0 GeV Taiwan Photon Source of the National Synchrotron Radiation Research Center are reported. The beamline is designed for studies of biological structures and kinetics in a wide range of length and time scales, from angstrom to micrometre and from microsecond to minutes. A 4 m IU24 undulator of the beamline provides high-flux X-rays in the energy range 4.0-23.0 keV. MoB4C double-multilayer and Si(111) double-crystal monochromators (DMM/DCM) are combined on the same rotating platform for a smooth rotation transition from a high-flux beam of ∼4 × 1014 photons s-1 to a high-energy-resolution beam of ΔE/E ≃ 1.5 × 10-4; both modes share a constant beam exit. With a set of Kirkpatrick-Baez (KB) mirrors, the X-ray beam is focused to the farthest SAXS detector position, 52 m from the source. A downstream four-bounce crystal collimator, comprising two sets of Si(311) double crystals arranged in a dispersive configuration, optionally collimate the DCM (vertically diffracted) beam in the horizontal direction for ultra-SAXS with a minimum scattering vector q down to 0.0004 Å-1, which allows resolving ordered d-spacing up to 1 µm. A microbeam, of 10-50 µm beam size, is tailored by a combined set of high-heat-load slits followed by micrometre-precision slits situated at the front-end 15.5 m position. The second set of KB mirrors then focus the beam to the 40 m sample position, with a demagnification ratio of ∼1.5. A detecting system comprising two in-vacuum X-ray pixel detectors is installed to perform synchronized small- and wide-angle X-ray scattering data collections. The observed beamline performance proves the feasibility of having compound features of high flux, microbeam and ultra-SAXS in one beamline.

[Construction of RNA interference (RNAi) lentiviral expression vector of DEK gene and its effect on the biological behavior of liver cancer cells].

Objective: To construct RNA interference (RNAi) lentiviral expression vector of DEK gene, and to explore its effect on the biological behavior of liver cancer cells. Methods: Double-stranded oligo DNAs were annealed and synthesized according to the interference sequence of DEK gene by RNAi technology. Small interfering RNA expression vector pLKO.1 was cloned after enzymatic digestion. The recombinant lentiviral pLKO.1-sh hDEK was constructed, and then the virus supernatant was collected, packed and infected by 293T cells. Real-time reverse transcription PCR (RT-PCR) and Western blot were used to detect DEK expression in human liver cancer cells Bel-7402, Hu-7, SmMC-7721 and HepG2, and DEK knockdown efficiency in each group of lentivirus-infected cells. Cell proliferation ability, cloning ability, apoptosis and migration ability were detected by cell counting kit-8 (CCK8), flow cytometry and scratch test, respectively. The t-test was used to compare the mean between the two groups, and one-way ANOVA was used to compare the multiple groups. Results: Enzymatic digestion and DNA sequencing results confirmed that the recombinant lentiviral vectors pLKO.1-sh hDEK1 and pLKO.1-sh hDEK3 were successfully constructed. RT-PCR and Western blot results showed that the expression of DEK in human liver cancer cells BEL-7402 and Huh7 cells was higher, and pLKO.1-sh hDEK3 was more effective in inhibiting the DEK gene expression (P < 0.05). Therefore, pLKO.1-sh hDEK3 was selected to infect BEL-7402 and Huh7 cells for subsequent functional experiments. CCK8 cell proliferation test result showed that the cell proliferation ability of BEL-7402 and Huh7 cells infected with recombinant lentivirus was weakened when compared with blank control and negative control group (P < 0.05). Apoptosis results showed that the apoptosis rate of knockdown group was higher than that of blank and the negative control group (P < 0.05). Cell scratch test result showed that the wound healing rate of knockdown group was lower than that of blank control and negative control group (P < 0.05), and the difference was statistically significant; however, there was no statistically significant difference between blank control and negative control group. Conclusion: Targeting DEK expression in silent liver cancer cells can inhibit the cell proliferation, migration ability, and induce apoptosis, which lays the foundation for further study of the role of DEK gene in liver cancer.

Dysregulation of Bmi1 promotes malignant transformation of hepatic progenitor cells.

Adult hepatic progenitor cells (HPCs) are involved in a wide range of human liver diseases, including hepatocellular carcinoma (HCC). Bmi1 has been reported to have vital roles in stem cell self-renewal and carcinogenesis. We have previously demonstrated that Bmi1 is upregulated in HCC with bile duct tumor thrombi, a subtype of HCC characterized by profuse expression of hepatic stem cell markers. However, the function of Bmi1 in HPCs has not yet been well elucidated. The current study was designed to investigate the effects of Bmi1 on the biological properties of rat HPCs. To accomplish this, Bmi1 was silenced or enhanced in two HPC cell lines (WB-F344 and OC3) by, respectively, using either small interfering RNA against Bmi1 or a forced Bmi1 expression retroviral vector. The biological functions of Bmi1 in HPCs were investigated through cell proliferation assays, colony-formation assays, cell cycle analysis and invasion assays, as well as through xenograft-formation assays. In this study, genetic depletion of Bmi1 repressed cell proliferation, colony formation and invasion in both assessed HPC cell lines relative to controls. Conversely, forced expression of Bmi1 in two HPCs cell lines promoted cell proliferation, colony formation and invasion in vitro. Aldehyde dehydrogenase (ALDH) assay revealed a significant increase in the number of ALDH-positive cells following the forced expression of Bmi1 in HPCs. Most importantly, transplantation of forced Bmi1 expression HPCs into nude mice resulted in the formation of tumors with histological features of poorly differentiated HCC. Taken together, our findings indicate that forced expression of Bmi1 promotes the malignant transformation of HPCs, suggesting Bmi1 might be a potential molecular target for the treatment of HCC.

Cloning, characterization, and expression of cadmium-induced metallothionein-2 gene from earthworm Pheretima aspergillum (E. Perrier).

Metallothioneins (MTs) are ubiquitous metal-binding, cysteine-rich proteins, associated with metal accumulation and thus providing protection against toxic heavy metals such as cadmium (Cd). To investigate the mechanisms of enrichment of Cd in the earthworm Pheretima aspergillum, we isolated and cloned metallothionein-2 (MT-2) cDNA (538 bp) from P. aspergillum, analyzed its sequence, and examined MT-2 transcription levels by relative quantitative real-time PCR under different concentrations of Cd. The sequence of P. aspergillum MT-2 cDNA and its putative amino acid sequence were highly similar to sequences from other earthworms. The induction with Cd increased the MT-2 gene transcription level in a dose-dependent manner. In addition, earthworm recombinant MT-2 exhibited high Cd bioaccumulation ability in vitro. These results suggested that MT-2 plays an important role in tolerance and accumulation of Cd in P. aspergillum.

Comparative and joint analyses of gene expression profiles under drought and rewatering in Arabidopsis.

Drought is a major limiting factor in crop production. Rewatering is a process opposite to drought, allowing plants to recover to their normal physiological state. To understand more thoroughly the set of genes involved in plant response to drought, we comparatively and jointly analyzed the microarray data of drought and rewatering experiments in Arabidopsis. A total of 3833 differentially expressed genes (DEGs) were identified. Among them, ~74% were proven to be co-regulated by drought and rewatering. Drought and rewatering showed contrary regulatory effects on almost all of these co-regulated genes. Only ~6% of the DEGs were significantly regulated by drought alone, and the remaining ~20% were significantly regulated by rewatering alone. However, gene ontology analysis suggested that those "rewatering-only" genes also appeared to be related, either directly or indirectly, to drought response.

Manipulation of dopamine d1-like receptor activation in the rat medial prefrontal cortex alters stress- and cocaine-induced reinstatement of conditioned place preference behavior.

These studies examined the ability of the dopamine D1-like agonist SKF 81297 and D1-like antagonist SCH 23390 in the medial prefrontal cortex to alter the reinstatement of cocaine-induced conditioned place preference behavior. Male Sprague-Dawley rats were fitted with bilateral cannulae over the medial prefrontal cortex and subsequently trained in a conditioned place preference task. Animals were trained in this task using four pairings of cocaine (12 mg/kg, i.p.). Conditioned place preference was demonstrated in all animals, and this behavior was then extinguished over a 5-10-day period before testing for reinstatement. Just prior to reinstatement by immobilization stress or a cocaine priming injection (5 mg/kg, i.p.), a microinjection of the D1-like receptor antagonist SCH 23390 (0.01, 0.1 or 1.0 microg/side), or the D1-like receptor agonist SKF 81297 (0.1, 0.3 or 1.0 microg/side) was given into the medial prefrontal cortex. SCH 23390 blocked both stress- and cocaine-induced reinstatement of conditioned place preference after the two higher doses were administered into the medial prefrontal cortex. The highest dose of SKF 81297 (1.0 microg/side) prevented immobilization stress- but not cocaine-induced reinstatement. The highest dose of these drugs given in the absence of stress or cocaine did not produce reinstatement. The results indicate that immobilization stress given within the place-preference chamber is capable of producing reinstatement of cocaine-seeking behavior. The microinjection studies suggest that D1-like receptor antagonism within the prefrontal cortex is sufficient to block reinstatement by stress and cocaine. Furthermore, the results from D1-like receptor activation in the medial prefrontal cortex point to utilization of different neural pathways for stress- and cocaine-induced reinstatement.

Regulation of medial prefrontal cortex dopamine by alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate/kainate receptors.

In the medial prefrontal cortex, repeated cocaine produces tolerance of the extracellular dopamine response to subsequent cocaine injection. These studies characterized the influence of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate/kainate receptors on the medial prefrontal cortex dopamine response to acute cocaine, amphetamine and potassium chloride as a first step to assess whether these receptor subtypes may be candidates for mediating dopamine tolerance after repeated cocaine. Local infusion of 10 microM 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) produced an approximate 40% increase in dopamine levels in the medial prefrontal cortex, while a 30 microM dose did not alter basal levels infused over a 3-h period. Thus, 30 microM CNQX was chosen for the remaining experiments, and was infused for 1 h prior to and during all in vivo treatments. Local medial prefrontal cortex infusion of the 30 microM dose blocked the small increase in dopamine levels elicited by systemic saline injection (maximum of 26%), as well as the much larger increase in response to acute cocaine injection (maximum of 340%). Local infusion of D-amphetamine (3 and 30 microM) through the probe increased dopamine to 300 and 600% of basal levels, respectively. Co-infusion of CNQX partially blocked the response for the first 40 min, but dopamine levels recovered by 60 min later. Local infusion of 100 mM potassium chloride elicited a 600% increase in dopamine levels, which was attenuated approximately 50% by CNQX co-infusion. Potassium-stimulated release of dopamine was also measured in vitro in medial prefrontal cortical and striatal tissue. By 30 s after potassium addition, dopamine levels increased to 800% above baseline in the medial prefrontal cortex, and this increase was blocked by the presence of 30 microM CNQX. In contrast, potassium-stimulated dopamine release in striatal tissue was approximately 250% above basal levels, with no effect of CNQX on dopamine release. Locomotor behavior collected during dialysis experiments demonstrated that increased activity induced by local infusion of potassium chloride was severely attenuated by co-infusion of 30 microM CNQX, while no effects of this drug were found for cocaine-elicited behavior. These results suggest a potent influence of glutamate via alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate/kainate receptors on extracellular dopamine in the medial prefrontal cortex, and these receptors may regulate dopamine release through a presynaptic mechanism. The findings may help elucidate the role of medial prefrontal cortex dopamine-glutamate interactions in drug abuse and stress- and drug-precipitated psychosis.

Dopamine D1 receptor activation in the medial prefrontal cortex prevents the expression of cocaine sensitization.

This study examined whether microinjection of the full D1 agonist, SKF 81297, or the D1 antagonist, SCH 23390, into the medial prefrontal cortex (mPFC) would alter the expression phase of cocaine sensitization. Male Sprague-Dawley rats were administered saline or cocaine (15 mg/kg, i.p.) once per day for seven consecutive days. After 8 to 17 days withdrawal, rats received a bilateral intra-mPFC microinjection of SKF 81297: either 0, 0.03, 0.1, or 0.3 microg/side; SCH 23390: either 0, 0.1, 0.3, or 1.0 microg/side; or a combination of 0.1 microg of SKF 81297 + 0.3 microg of SCH 23390, followed by an i.p. saline or cocaine (15 mg/kg, i.p.) injection. In naïve rats, vertical activity was elevated by the two lower doses of SKF 81297. A similar enhancement of cocaine-induced activity was observed in daily saline rats at the highest dose tested. In contrast, SKF 81297 suppressed the expression of sensitization to cocaine. This blockade of sensitization was prevented by coinfusion of SCH 23390. Infusion of SCH 23390 alone into the mPFC in daily saline and cocaine-pretreated rats demonstrated a suppression of cocaine-induced locomotion in daily saline-pretreated rats after the highest dose, but a slight augmentation of activity after the lowest dose in daily cocaine-pretreated rats. These results demonstrate a contribution by mPFC D1 receptors in the expression of cocaine sensitization and further suggest that the effects of D1 receptor activation in the mPFC occur in opposite directions in daily saline versus daily cocaine-pretreated rats.

Exposure to repeated low-level formaldehyde in rats increases basal corticosterone levels and enhances the corticosterone response to subsequent formaldehyde.

Low-level exposure to volatile organic compounds may produce symptoms in humans reporting multiple chemical sensitivity (MCS) through altered hypothalamic-pituitary-adrenal (HPA) axis functioning. We determined whether repeated formaldehyde (Form) exposure would alter corticosterone (CORT) levels in a rat model of MCS. Male Sprague-Dawley rats were given acute chamber exposures to Air or Form (0.7 or 2.4 ppm), and trunk blood was collected 20 or 60 min later. All groups showed increased CORT levels above naïve basal levels at 20 min and a return to baseline by 60 min, with no differences between treatment groups. The second experiment examined the effect of repeated Form exposure (1 h/day x 5 days/week x 2 or 4 weeks) on basal CORT levels and after a final challenge. Basal CORT was increased above naïve values after 2 week exposure to Air or 0.7 ppm Form. By 4 week, CORT levels in the Air group returned to naïve values, but remained elevated in the 0.7 ppm Form group. There were no differences in basal CORT levels among either 2.4 ppm exposed groups. After a final Air or Form challenge, the 2 and 4 week Air and 0.7 ppm Form groups had elevated CORT levels similar to their acute response, while the 2 and 4 week 2.4 ppm Form groups had elevated CORT levels compared to their acute response, indicating enhanced reactivity of the HPA axis to subsequent Form. These findings suggest that altered HPA axis functioning occurs after repeated low-level Form exposure, and may have implications for mechanisms mediating MCS in humans.

Differential effects of L-deprenyl on MPP+- and MPTP-induced dopamine overflow in microdialysates of striatum and nucleus accumbens.

The present studies investigated the effects of L-deprenyl, 1-methyl-4-phenylpyridinium ion (MPP+) and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) on the efflux of dopamine and its metabolites in microdialysates of striatum and nucleus accumbens in rats. L-Deprenyl or L-amphetamine perfusion into striatum had no effects on basal dopamine efflux, though L-deprenyl reduced the basal efflux of dihydroxyphenylacetic acid and homovanillic acid. MPP+ or MPTP perfusion into striatum significantly increased the dopamine efflux, and the action of MPTP was more potent than that of MPP+. Pretreatment with L-deprenyl antagonized the actions of MPP+ and MPTP. The striatal dopamine efflux of rats was gradually restored by itself after the overflow caused by 2-h perfusion of the dopaminergic neurotoxins, while L-deprenyl could not accelerate the recovery. Perfusion with L-deprenyl or L-amphetamine, but not pargyline, into nucleus accumbens increased the dopamine efflux in a dose-dependent fashion, which could be antagonized by haloperidol pretreatment. MPP+ or MPTP perfusion into nucleus accumbens also increased the dopamine efflux, and the action of MPTP was also more potent than that of MPP+. Pretreatment with L-deprenyl could not antagonize the actions of MPP+ and MPTP. These findings suggest that L-deprenyl, MPP+ and MPTP induce differential effects on nigrostriatal and mesolimbic dopaminergic pathways in vivo. L-Deprenyl has neuroprotective rather than neurorestorative action against MPP+- and MPTP-induced dopamine overflow from striatum. Further, L-deprenyl-induced dopamine overflow from nucleus accumbens may explain the amphetamine-like reinforcing property of L-deprenyl.

I-stepholidine facilitates inhibition of mPFC DA receptors on subcortical NAc DA release.

AIM: To determine whether the D1 agonistic action of (-)-stepholidine (SPD) on the medial prefrontal cortex (mPFC) neuron is involved in the modulation of evoked subcortical dopamine (DA) release from nucleus accumbens (NAc) of rats. METHODS: With the microinjection of SPD into the mPFC, the ventral tegmental area (VTA)-stimulated or amphetamine (AMP)-evoked DA efflux in the NAc was detected by microdialysis + HPLC-ECD in the 6-hydroxydopamine (6-OHDA)-lesioned and intact rats. RESULTS: The depletion of DA in the mPFC did not modify both the basal level and the VTA-stimulated DA efflux in the NAc, but significantly facilitated the AMP (20 mumol.L-1)-evoked DA efflux within the NAc. It indicates that the mPFC DA system is involved in the regulation of evoked DA release in the NAc. Besides, the AMP-evoked increase of the extracellular DA release in the NAc was significantly attenuated by SPD (10, 30 mmol.L-1) microinjection into the mPFC, though this injection of SPD could not alter the response of DA release by the stimulation of the VTA. Furthermore, the inhibitory effect of SPD on the AMP-evoked DA efflux could be partially reversed by intravenous administration of D1 antagonist Sch-23390 (1 mg.kg-1), but not by D2 antagonist spiperone. CONCLUSION: SPD is capable of enhancing the function of D1 receptors in the mPFC, by which it facilitates the inhibition of DA release in the NAc.

Neuroprotective rather than neurorescue or neurorestorative effect of selegiline against MPTP-induced dopaminergic toxicity.

AIM: To study the neuroprotective, neurorescue, neurorestorative effects of selegiline (Sel) on nigrostriatal dopaminergic neuronal system and its inhibition of brain monoamine oxidase B (MAO-B). METHODS: The striatal levels of dopamine and its metabolites were measured using HPLC with electrochemical detection (HPLC-EC). The inhibition of MAO-B was tested by an improved fluorimetric assay. RESULTS: 1-Methyl-4-phenyl-1,2,3,6-tetrahydro-pyridine (MPTP) (30 mg.kg-1 i.p.) reduced the striatal dopamine level by 73% in mice. Selegiline (Sel, 10 mg.kg-1 i.p.) before, but not after, MPTP treatment protected against MPTP-induced nigrostriatal dopaminergic neurotoxicity. There were no differential effects between Sel and saline treatments on the recovery of striatal dopamine levels, which were partially restored during 2 wk. 1-Methyl-4-phenylpyridinium (MPP+) (5 mg.kg-1 i.p.) produced no dopaminergic neurotoxicity. Furthermore, Sel selectively and irreversibly inhibited mouse brain MAO-B in vitro (IC50 = 17 nmol.L-1, 95% confidence limits = 14-20 nmol.L-1). CONCLUSION: Selegiline has neuroprotective rather than neurorescue or neurorestorative effects on MPTP-induced nigrostriatal dopaminergic neuronal degeneration, which is directly pertinent to its selective and irreversible inhibition of brain MAO-B activity.

Involvement of monoamine oxidase inhibition in neuroprotective and neurorestorative effects of Ginkgo biloba extract against MPTP-induced nigrostriatal dopaminergic toxicity in C57 mice.

The present study investigated the neuroprotective and neurorestorative effects of Ginkgo biloba extract (EGb 761) and its two components ginkgolides A (BN52020) and B (BN52021) in mice. 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) (30 mg/kg/d i.p. for six days) significantly reduced striatal dopamine (DA) levels in C57 mice measured by high performance liquid chromatography with electrochemical detection (HPLC-EC). When C57 mice were pretreated with EGb 761 (20, 50, 100 mg/kg/d i.p.) for 7 days and then treated with the same extract 30 min before MPTP injection for 6 days, the neurotoxic effect of MPTP was antagonized in a dose-dependent fashion. Similar treatment with ginkgolides A and B (5, 10, 50 mg/kg/d i.p.) showed no protective effect. When C57 mice were treated with EGb 761 (50 mg/kg/d i.p.) after MPTP-lesion, the recovery of striatal dopamine (DA) levels was accelerated. However, similar treatment with ginkgolides A or B (10 mg/kg/d i.p.) did not show any effect. EGb 761, but not ginkgolides A and B, nonselectively inhibited mouse brain MAO activity in vitro (IC50 = 36.45 +/- 1.56 microg/ml) tested by an improved fluorimetric assay. The results demonstrate that EGb 761 administered before or after MPTP treatment effectively protects against MPTP-induced nigrostriatal dopaminergic neurotoxicity and that the inhibitory effect of EGb 761 on brain MAO may be involved in its neuroprotective effect.

Immunosuppressive effects of dihydroetorphine, a potent narcotic analgesic, in dihydroetorphine-dependent mice.

The immunomodulatory effects of dihydroetorphine were systematically investigated in subchronically treated mice. In a dose-dependent fashion, dihydroetorphine (total doses at 444.5, 889 and 1778 microg/kg) lowered the increase of body weight, decreased the weight of the spleen and thymus, weakened the delayed-type hypersensitivity, reduced the generation of antibody-forming cells, inhibited splenic lymphocyte proliferation induced by concanavalin A and lipopolysaccharide, suppressed the production of interleukin-2 in the supernatant of splenocytes induced by concanavalin A, and depleted the ratio of CD4+ and CD8+ subpopulations. Moreover, the physical dependence on dihydroetorphine was also evaluated to confirm that the immunosuppression was concomitant with the addiction to the drug. These results demonstrate that subchronic treatment with dihydroetorphine dose dependently suppresses both humoral and cell-mediated immune function, and that the immunosuppressive effects of dihydroetorphine are much more potent than those of morphine.

Time-related mapping of quantitative trait loci underlying tiller number in rice.

Using time-related phenotypic data, methods of composite interval mapping and multiple-trait composite interval mapping based on least squares were applied to map quantitative trait loci (QTL) underlying the development of tiller number in rice. A recombinant inbred population and a corresponding saturated molecular marker linkage map were constructed for the study. Tiller number was recorded every 4 or 5 days for a total of seven times starting at 20 days after sowing. Five QTL were detected on chromosomes 1, 3, and 5. These QTL explained more than half of the genetic variance at the final observation. All the QTL displayed an S-shaped expression curve. Three QTL reached their highest expression rates during active tillering stage, while the other two QTL achieved this either before or after the active tillering stage.

The amphetamine-like reinforcing effect and mechanism of L-deprenyl on conditioned place preference in mice.

The present study investigated the reinforcing effect of L-deprenyl on conditioned place preference in mice and its mechanism. Conditioned place preference was induced by 10 and 25 mg/kg L-deprenyl in a dose-dependent fashion during five consecutive conditioning days, and its reinforcing property was about five-fold less potent than that of L-amphetamine. Pretreatment with the dopamine antagonist, haloperidol (1 mg/kg i.p.), effectively blocked the place preference produced by L-deprenyl (10 and 25 mg/kg i.p.) and L-amphetamine (2 and 5 mg/kg i.p.), but haloperidol itself produced no place aversion. The neurotoxin, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), 30 mg/kg did not modify the place preference induced by both L-deprenyl and L-amphetamine, though the dopamine concentration in striata assayed by high performance liquid chromatography with electrochemical detection (HPLC-EC) was significantly reduced. These results suggest that L-deprenyl has amphetamine-like reinforcing properties. The reinforcing effect of L-deprenyl may be mediated by central dopaminergic neuronal systems, while the nigrostriatal dopaminergic pathway is not involved.

Image contrast enhancement based on a histogram transformation of local standard deviation.

The adaptive contrast enhancement (ACE) algorithm, which uses contrast gains (CG's) to adjust the high-frequency components of images, is a well-known technique for medical image processing. Conventionally, the CG is either a constant or inversely proportional to the local standard deviation (ILSD). However, it is known that conventional approaches entail noise overenhancement and ringing artifacts. In this paper, we present a new ACE algorithm that eliminates these problems. First, a mathematical model for the LSD distribution is proposed by extending Hunt's image model. Then, the CG is formulated as a function of the LSD. The function, which is nonlinear, is determined by the transformation between the LSD histogram and a desired LSD distribution. Using our formulation, it can be shown that conventional ACE's use linear functions to compute the new CG's. It is the proposed nonlinear function that produces an adequate CG resulting in little noise overenhancement and fewer ringing artifacts. Finally, simulations using some X-ray images are provided to demonstrate the effectiveness of our new algorithm.

Involvement of mu-opioid receptors and alpha-adrenoceptors in the immunomodulatory effects of dihydroetorphine.

The present study investigated the effects of acutely administered dihydroetorphine on mitogen-stimulated lymphocyte proliferation and lymphokine production in mice. These immune functions were significantly suppressed by dihydroetorphine at 24 microg/kg and 128 microg/kg in a dose-dependent fashion. This study further examined the involvement of micro-opioid receptors and alpha-adrenoceptors in the immunomodulatory effects of dihydroetorphine. The micro-opioid receptor antagonist, naloxone (4 mg/kg), and alpha-adrenoceptor antagonist, phentolamine (10 mg/kg), but not the beta-adrenoceptor antagonist, propranolol (10 mg/kg), effectively blocked dihydroetorphine-induced suppression of splenic lymphocyte proliferation and lymphokine production. These results demonstrate that dihydroetorphine has significant immunosuppressive effects in mice and the mechanisms of these effects may lie in its interactions with opioid receptors and adrenergic pathways.