Long-term protective effects of methamphetamine preconditioning against single-day methamphetamine toxic challenges

Methamphetamine (METH) use is associated with neurotoxic effects which include decreased levels of dopamine (DA), serotonin (5-HT) and their metabolites in the brain. We have shown that escalating METH dosing can protect against METH induced neurotoxicity in rats sacrificed within 24 hours after a toxic METH challenge. The purpose of the current study was to investigate if the protective effects of METH persisted for a long period of time. We also tested if a second challenge with a toxic dose of METH would cause further damage to monoaminergic terminals. Saline-pretreated rats showed significant METH-induced decreases in striatal DA and 5-HT levels in rats sacrificed 2 weeks after the challenge. Rats that received two METH challenges showed no further decreases in striatal DA or 5-HT levels in comparison to the single METH challenge. In contrast, METH-pretreated rats showed significant protection against METH-induced striatal DA and 5-HT depletion. In addition, the METH challenge causes substantial decreases in cortical 5-HT levels which were not further potentiated by a second drug challenge. METH preconditioning provided almost complete protection against METH -induced 5-HT depletion. These results are consistent with the idea that METH pretreatment renders the brain refractory to METH-induced degeneration of brain monoaminergic systems.

Tuning the limiting thickness of a thin oxide layer on Al(111) with oxygen gas pressure

We report an x-ray photoelectron spectroscopy study of the oxidation of Al(111) surfaces at room temperature, which reveals that the limiting thickness of an aluminum oxide film can be tuned by using oxygen pressure. This behavior is attributed to a strong dependence of the kinetic potential on the oxygen gas pressure. The coverage of oxygen anions on the surface of the oxide film depends on the gas pressure leading to a pressure dependence of the kinetic potential. Our results indicate that a significantly large oxygen pressure (>1  Torr) is required to develop the saturated surface coverage of oxygen ions, which results in the maximum kinetic potential and therefore the saturated limiting thickness of the oxide film.

Effect of adenovirus-mediated brain derived neurotrophic factor in early retinal neuropathy of diabetes in rats

AIM

To observe effect of adenovirus-mediated brain derived neurotrophic factor in early retinal neuropathy of diabetes in rats.

METHODS

Adult male Wistar rats, 9 weeks of age, were injected intraperitoneally with STZ to induce diabetes. Two weeks after the models were established, Ad.BDNF was administered into the vitreous cavities of rats. Four weeks after the models were set up, the rats were killed and the retina was removed for Western blotting and whole-mount immunohistochemistry for tyrosine hydroxylase (TH) to observe the changes of TH and dopaminergic amacrine cells in retina.

RESULTS

The protein levels of TH and the number of positive staining dopaminergic amacrine cells and the staining gray scale of experimental group without Ad.BDNF were lower statistically. But there was no statistically significant difference between the experimental group with Ad.BDNF and control group.

CONCLUSION

In the early stage of STZ diabetic, the administration of Ad.BDNF into the vitreous cavities can increase TH protein levels and the density of dopaminergic amacrine cells in the STZ rats' retina.

Progressive changes in hepatoma cells stably transfected with hepatitis B virus X gene

OBJECTIVE

The aim of this study is to investigate the molecular mechanism of hepatocellular carcinoma (HCC) development induced by hepatitis B virus X protein (HBx).

METHODS

We previously established a H7402-X cell line that constitutively expresses HBx protein. In the present study, H7402-X gene expression profiles and proteins were examined using cDNA microarrays and Western blot analysis. Apoptosis was induced by adriamycin in H7402-X cells. The transcriptional activities of NF-kappaB and AP-1 were examined using a luciferase reporter gene.

RESULTS

The DNA expression profiles identified candidate genes showing aberrant expression in cells overexpressing HBx. Western blot analysis showed that cyclin D, cyclin E, survivin, Bcl-2, and PCNA were up-regulated, whereas p27 was down-regulated in H7402-X cells. Treatment with RNAi targeting HBx mRNA led to the down-regulation of these genes. H7402-X cells were resistant to adriamycin-induced apoptosis. Luciferase reporter gene analysis revealed that HBx induces the transcriptional activities of NF-kappaB and AP-1.

CONCLUSION

Our data provide additional insight into cellular targets of HBx, which allows a better understanding of HBx function and the progressive changes during HBx-mediated hepatocarcinogenesis.

Novel biophysical techniques for investigating long-term cell adhesion dynamics on biomaterial surfaces

Cell adhesion on biomaterial surface is crucial for the regeneration and function of clinically viable cell and tissues. In turn, the cellular phenotypes, following the mechanochemical transduction of adherent cells on biomaterials, are directly correlated to the biophysical responses of cells. However, the lack of an integrated bio-analytical system for probing the cell-substrate interface poses significant obstacles to understanding the behavior of cells on biomaterial surface. We have developed a novel method, based on the principle of confocal reflectance interference contrast microscopy (C-RICM) that has enabled us to study the biomechanical deformation of cells on biomaterial surfaces. In this article, we would like to describe our recent development of the C-RICM system that integrates a confocal fluorescence microscope, phase contrast microscope and GFP expression system. We shall demonstrate the system by determining the adhesion contact kinetics, initial deformation rate, cytoskeleton structures of adherent cells on extracellular matrices (e.g., collagen and fibronectin) and biodegradable polymer (e.g., poly(lactic acid)) during long-term culture. We shall demonstrate that this unique approach could provide valuable biophysical information necessary for designing optimized biomaterial surfaces for cell/tissue regeneration applications.

A tumor-specific conditionally replicative adenovirus vector expressing TRAIL for gene therapy of hepatocellular carcinoma

We constructed a novel hepatocellular carcinoma-specific conditionally replicative adenovirus (CRAd). This adenovirus, designated Ad.HS4.AFP.E1A/TRAIL, expresses E1A to mediate viral replication and TRAIL to enhance HCC-killing efficacy under the control of a modified AFP promoter. An insulator HS-4 was placed in front of the AFP promoter to enhance the fidelity of the heterologous promoter. This virus was shown to have specific cytolytic activity in AFP-expressing HCC cells in vitro. Furthermore, the replication efficiency of Ad.HS4.AFP.E1A/TRAIL correlated well with AFP expression of the host cells, showing a 100-fold and 1 000 000-fold decrease in the low-and non-AFP-expressing HCC cells, respectively, compared to the high AFP-expressing HCC cells. An increase in mRNA of TRAIL and the elevated Caspase-3 activity were also observed in Ad.HS4.AFP.E1A/TRAIL-infected HCC cells. These results indicated that TRAIL expression from the viral vector activated the Caspase-3 enzymatic capacity and the HCC cells were sensitive to TRAIL. In vivo, Ad.HS4.AFP.E1A/TRAIL effectively prevented the growth of low AFP-expressing BEL-7404 xenografts. These results indicate that Ad.HS4.AFP.E1A/TRAIL could provide a new strategy of gene therapy for HCC.

[Transformation of attached cells derived from fetal umbilical cord blood induced by conditional medium of hepatoma cells]

BACKGROUND & OBJECTIVE

Stem cells derived from fetal umbilical cord blood are of undifferentiated at early stage. They are sensitive to stimulations from the environment, and may be transformed under the effects of carcinogenic factors. This study was to explore the sensitivity of stem cells derived from fetal umbilical cord blood to carcinogenic factors.

METHODS

Mononuclear cells were isolated from fetal umbilical cord blood, and the attached cells were cultured in the medium containing 10% conditional medium of HepG2 hepatoma cells. A new cell line was gained, termed H-UCB. The biological features of H-UCB cells were detected by electron microscopy, karyotype analysis, cell cytometry, Western blot, and colony formation assay.

RESULTS

H-UCB cells proliferated faster after passage 3. The cells were fibroblast-like and hepatocyte-like, with the ratio of nucleus to cytoplasm increased. Under electron microscope, many microvilli on the surface and numbers of vacuoles in the cytoplasm of the cells were observed, the nuclei were large and irregular, endocytosis phenomena were noticed. Karyotype analysis indicated that the cells were heteroploid, and the number of chromosomes was between 50 and 70. Flow cytometry data indicated that the proliferation period was 22.9 h, and the karyotype was between diploid and tetraploid. Western blot showed that c-Myc protein and proliferating cell nuclear antigen (PCNA) were overexpressed in H-UCB cells. According to flow cytometry, the positive rates of surface markers of H-UCB cells were 79.0% for CD105, 1.2% for CD34, and 12.2% for CD106; those of control HepG2 cells were 15.0% for CO105, 9.8% for CD34, and 1.4% for CD106. The colony formation rate of H-UCB cells in soft agar was (13.2+/-2.6)%.

CONCLUSION

H-UCB cells are derived from endothelial cells, and are transformed as malignant cells with tumor cell characteristics.

Hepatitis B virus X protein upregulates survivin expression in hepatoma tissues

The hepatitis B virus X protein (HBx) plays an important role in the development of hepatocellular carcinoma (HCC). The relationship was examined between HBV antigens and IAP (inhibitor of apoptosis) family in development of HCC. The expression levels of HBV antigens (HBsAg, HBcAg, and HBxAg) and members of the IAP family (survivin, XIAP, cIAP-1, and cIAP-2) were detected immunohistochemically in tissues from 34 cases of HCC and 30 cases of liver cirrhosis. The positive rate of survivin was higher than these three molecules in all three tissue types (P < 0.05). The positive rates of HBxAg and survivin were high in HCC (76.5% and 88.2%), paratumor (85.3% and 91.2%), and liver cirrhosis (100% and 93.3%) tissues, with no significant differences between the survivin- and HBxAg-positive rates (each P > 0.05). To examine the effect of HBx on survivin expression, plasmid pCMV-X (encoding the HBx gene) was transfected transiently with or without plasmid pcDNA3-sur (encoding the survivin gene) into H7402 hepatoma cells and L-O2 human normal liver cells. Cells over-expressing HBx alone showed increased apoptosis along with a dose-dependent increase in survivin levels. However, co-expression of survivin inhibited the HBx-induced apoptosis. To examine the effect of HBx on survivin in hepatoma cells without apoptosis, plasmid pCMV-X was transfected stably into human hepatoma H7402 cells and L-O2 cells. These H7402-X and L-O2-X cells showed high-level expression of both HBx and survivin, but did not show apoptosis. The addition of pSilencer 3.0-X, an RNAi vector targeting the HBx gene, reduced the expression levels of survivin protein in H7402-X cells. Collectively, these data demonstrate that HBx upregulates survivin expression in hepatoma tissues, suggesting that HBx and survivin may both be involved in carcinogenesis of HCC.

Automatic analysis of image of surface structure of cell wall-deficient EVC

Some computer applications for cell characterization in medicine and biology, such as analysis of surface structure of cell wall-deficient EVC (El Tor Vibrio of Cholera), operate with cell samples taken from very small areas of interest. In order to perform texture characterization in such an application, only a few texture operators can be employed: the operators should be insensitive to noise and image distortion and be reliable in order to estimate texture quality from images. Therefore, we introduce wavelet theory and mathematical morphology to analyse the cellular surface micro-area image obtained by SEM (Scanning Electron Microscope). In order to describe the quality of surface structure of cell wall-deficient EVC, we propose a fully automatic computerized method. The image analysis process is carried out in two steps. In the first, we decompose the given image by dyadic wavelet transform and form an image approximation with higher resolution, by doing so, we perform edge detection of given images efficiently. In the second, we introduce many operations of mathematical morphology to obtain morphological quantitative parameters of surface structure of cell wall-deficient EVC. The obtained results prove that the method can eliminate noise, detect the edge and extract the feature parameters validly. In this work, we have built automatic analytic software named "EVC.CELL".

Endogenous BDNF protein is increased in adult rat hippocampus after a kainic acid induced excitotoxic insult but exogenous BDNF is not neuroprotective

Systemic administration of the excitotoxin kainic acid to adult rats results in a well defined pattern of loss of the CA1 and CA3 pyramidal neurons of the hippocampus. Prior to this neuronal loss, brain-derived neurotrophic factor (BDNF) mRNA is substantially increased. We show here that BDNF protein is increased after excitotoxic insult in specific areas of the hippocampus, reaching maximal levels 24 h after the insult. BDNF protein levels in the hippocampus increase in direct relation to the severity of seizure. Up to 7 days after injection of kainic acid, levels of full-length TrkB protein were unchanged, whereas levels of truncated TrkB protein were significantly increased by 12 h. To determine whether elevations in BDNF protein levels are potentially beneficial to hippocampal neurons exposed to an excitotoxic stress, we infused exogenous BDNF prior to and during the period of neuronal death caused by kainic acid. We find that administration of high levels of exogenous BDNF does not affect severity of seizure, but does in fact, exacerbate the injury caused by kainic acid, specifically to CA3 pyramidal neurons. Although there was a trend toward sparing of CA1 pyramidal neurons on the side infused with BDNF, this was not significant. In the same paradigm, infusion of exogenous NT-3 had no effect.

Anterograde transport of brain-derived neurotrophic factor and its role in the brain

The role of neurotrophins as target-derived proteins that promote neuron survival following their retrograde transport from the terminals to the cell bodies of neurons has been firmly established in the developing peripheral nervous system. However, neurotrophins appear to have more diverse functions, particularly in the adult central nervous system. Brain-derived neurotrophic factor (BDNF), for example, produces a variety of neuromodulatory effects in the brain that are more consistent with local actions than with long-distance retrograde signalling. Here we show that BDNF is widely distributed in nerve terminals, even in brain areas such as the striatum that lack BDNF messenger RNA, and that inhibition of axonal transport or deafferentation depletes BDNF. The number of striatal neurons that contain the calcium-binding protein parvalbumin was decreased in BDNF+/- and BDNF-/- mice in direct proportion to the loss of BDNF protein, which is consistent with anterogradely supplied BDNF having a functional role in development or maintenance. Thus the anterograde transport of BDNF from neuron cell bodies to their terminals may be important for the trafficking of BDNF in the brain.

[The clinical features and long-term follow-up of atrial fibrillation or atrial flutter complicating Wolff-Parkinson-White syndrome]

Twenty six patients (20 male, 6 female, aged 50 +/- 14) with recurrent episodes of atrial fibrillation or atrial flutter (Af/AF) associated with WPW syndrome were retrospectively studied and followed. During Af/AF, 17 patients showed ventricular preexcitation. Of them, 15 patients had hypotention, 8 syncope, 4 precipitating acute heart failure and 4 spontanous degenerated into ventricular fibrillation. Hypotention was found only in 2 of the 9 patients without pre-excited ventricular beats. The mean shortest prexcited R-R intervals of the former were shorter (247 +/- 47 ms) and the average ventricular rates (198 +/- 43 beat/min) were faster than those of the latter (393 +/- 80 ms & 144 +/- 22 beat/min) respectively (P < 0.01). When pre-excited Af/AF occurred, both cardioversion and antiarrhythmic agents of class I and II had marked effect in terminating the Af/AF or slowing pre-exicted ventricular responses. Digitalis and verapamil caused deterioration in the clinical condition of 6 patients (4 with hypotention, one syncope, and one ventricular fibrillation). Management of patients for WPW complicating Af/AF without pre-excited QRS was the same as for the ordinary Af/AF. Over a period of 53 +/- 44 months of follow-up, 5 died (3 of sudden death, one of heart failure, and one of noncardiac cause) in the group with preexcited Af/AF, but all of the patients without preexcited QRS during Af/AF were alive. Conclusion, clinical severity, response to the treatment, and long-term prognosis of patients of WPW with preexcited Af/AF are different from those without.

Neurotrophin-4/5 maintains the cholinergic phenotype of axotomized septal neurons

We examined the effect of intraseptal or intracerebroventricular (i.c. v.) infusions of NT-4/5 or intraseptal infusions of NGF on the level of immunohistochemical staining of choline acetyltransferase (ChAT)and the low-affinity nerve growth factor receptor (LNGFR)in the rat medial septum following unilateral transection of the fimbria. The extent of cell loss in the septum ipsilateral to the lesion, determined by cell counts of ChAT-immunopositive neurons and expressed as a ratio comparing the lesioned to the intact sides, was 0.28 in animals that received an infusion of phosphate-buffered saline (PBS). The ratios were 0.97 and 1.07 in animals that received an infusion of NT-4/5 into the ipsilateral ventricle and septum respectively. Septal infusions of NGF produced a ratio of ChAT-immunopositive cells of 1.03. The ratios of LNGFR-immunopositive neurons increased from 0.50 in PBS-infused animals to 0.79 and 0.83 in animals infused with NT-4/5 via the i.c. v. infusion of NT-4/5 or septal infusion of NT-4/5 or NGF. As determined by immunohistochemical staining, NT-4/5 infused into the lateral ventricle was detected in the periventricular portions of the forebrain ipsilateral to the infusion, while NT-4/5 or NGF infused intraseptally was detected in much of the septum, bilaterally. Furthermore, exogenous NT-4/5 or NGF was detected in numerous neuronal perikarya in the medial septal and diagonal band nuclei. These data demonstrate that, as with NGF, i.c.v. as well as septal infusions of NT-4/5 can maintain the phenotype of basal forebrain cholinergic neurons following axotomy.

Brain-derived neurotrophic factor (BDNF) prevents the degeneration of medial septal cholinergic neurons following fimbria transection

Brain-derived neurotrophic factor (BDNF), a member of the neurotrophin family, supports the survival of developing basal forebrain cholinergic neurons in vitro and is retrogradely transported by cholinergic neurons of the medial septum and diagonal band following intrahippocampal injections in vivo. To substantiate a potential role for BDNF in the maintenance of forebrain cholinergic neurons in the adult brain, we assessed the ability of BDNF to sustain the phenotype of medial septal cholinergic neurons following a unilateral transection of the fimbria. BDNF, NGF, or vehicle solutions were infused continuously in adult female rats either into the lateral ventricle (intracerebroventricularly) or directly into the septum for 2 weeks beginning at the time of the transection. In vehicle-infused animals, only 28% of the ChAT-immunoreactive neurons remained on the side ipsilateral to the lesion compared to the contralateral intact side. When infused intracerebroventricularly, both BDNF and NGF reduced the extent of the phenotypic loss, in that 44% and 68%, respectively, of the ChAT-immunopositive neurons remained on the lesioned side. Intraseptal infusion proved even more effective, in that following BDNF and NGF treatment 60% and 86%, respectively, of the normal complement of ChAT-immunopositive neurons were apparent on the side ipsilateral to the lesion. Similar results were obtained when an antibody to the low-affinity NGF receptor was used to identify the cholinergic neurons. To determine if the apparent greater efficacy of NGF compared to BDNF might be related to differences in delivery, we examined the patterns of distribution of radiolabeled BDNF and NGF injected into the lateral ventricle. 125I-BDNF showed only very little diffusion from the ventricles into the adjacent neural tissue and negligible retrograde labeling of the neurons within the basal forebrain. 125I-NGF, however, diffused readily into the brain, resulting in widespread retrograde labeling of basal forebrain neurons. A similarly limited distribution pattern was observed where BDNF was detected immunohistochemically in animals infused intracerebroventricularly (12 micrograms/d) for 2 weeks. In contrast, when delivered intraseptally, the same dose of BDNF exhibited a widespread diffusion within the surrounding neuropil and retrograde labeling of neurons in the medial septum and the vertical limb of the diagonal band. Thus, when delivered effectively, BDNF has a substantial capacity to rescue axotomized cholinergic neurons.

Medium-dependent dissociation of cytotoxic and GABA-releasing effects of N-methyl-D-aspartate (NMDA), alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) and kainate in rat cortical cultures

The excitotoxic cell death and the release of gamma-amino-butyric acid (GABA) evoked by excitatory amino acids (EAAs) were comparatively examined in rat cortical sister cultures grown in serum-free (N2) and serum-supplemented (SSM) media. Cell death was induced by 24 h exposure to 1 mM N-methyl-D-aspartate (NMDA), alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) or kainate. [3H]GABA release was evoked by 5 min exposure of preloaded cultures to 0.5 mM NMDA, AMPA or kainate. EAAs evoked remarkable GABA release in both N2 and SSM cultures, but caused toxic cell death in SSM cultures, only. Our findings indicate that functionally active EAA receptors do not necessarily mediate neurotoxicity and suggest that excitotoxicity can be prevented without blocking excitatory transmission.

[The clinical manifestation of arrhythmogenic right ventricular dysplasia]

Five patients, 4 male, 1 female with age ranging from 25 to 65 were included in the study. All the cases admitted into the hospital because of episodes of ventricular tachycardia (VT). Four associated with history of Adams-Stokes attacks. Their common manifestations are as followed: 1. Sustained LBBB VT associated with history of syncope and/or Adams-Stokes-Syndrome. 2. Inverted T waves in right precordial leads. 3. Positive ventricular late potential. 4. Relatively normal heart on physical examination and X-ray film. 5. Enlargement and dysfunction of right ventricle, 3 with a diverticulum-like bulging lesion at apex of right ventricle, proved by echocardiographic and nuclear angiocardiographic study. 6. Repeatedly induced VT during electrophysiological study. Our data suggest that arrhythmogenic right ventricular dysplasia (ARVD) should be suspected in patients with recurrent LBBB VT and relatively normal heart, especially, those with positive ventricular late potential. Right ventricle should be carefully investigated with echocardiography and nuclear angiocardiography to confirm the diagnosis. Four cases in the study were refractory to antiarrhythmic drug therapy and 2 of them were treated successfully with transcatheter electrical ablation, 1 with surgical intervention.

Prediction of terminal atrial myocardial repolarisation from incomplete phase 3 data

The duration of the monophasic action potential (MAP) carries prognostic antiarrhythmic information when the recording is done during sinus rhythm (SR) after DC conversion of atrial fibrillation (AF). This study analyses whether it is possible to predict MAP duration during sinus rhythm by analysing the atrial MAP during AF, even though complete myocardial repolarisation is never reached during this arrhythmia. We have therefore evaluated the estimated duration of the action potential (AP) and MAP by exponential extrapolation of phase 3 data. (1) AP studies were done on 11 human atrial myocardial specimens. Resting membrane potential (RMP) and AP duration were better identified when more data obtained during repolarisation were used for prediction. Thus the predicted RMP deviated on average by -0.4% of AF amplitude from the real RMP level when data to 90% repolarisation were used for extrapolation. AP duration at 90% repolarisation correlated well with the real AP duration (r = 0.88) at this level of data aquisition. (2) Continuous recording of atrial MAPs was done in 15 patients during AF and in 12 of these during SR after DC conversion. Resting myocardial repolarisation level during AF, RP(EST), and estimated MAP duration, MAPD(EST), could be calculated by exponential extrapolation in 12 patients. The actual repolarisation during fibrillation reached below 90% of the RP(EST) level in eight patients and below 70% in all 12. The MAP duration during SR could be predicted with increasing precision when data closer to the RP(EST) were used for calculation of MAPD(EST). Thus MAPD(EST) correlated well with SR MAP duration when data reaching at least 90% of RP were used (r = 0.85).(ABSTRACT TRUNCATED AT 250 WORDS)