Neuroprotective effects of LBP on brain ischemic reperfusion neurodegeneration

AIM

The present study was conducted to investigate whether LBP had a protective effect on cerebral ischemic reperfusion injury and to determine the possible mechanisms.

MATERIALS AND METHODS

Male Kunming (KM) mice were used to make the model cerebral artery occlusion/reperfusion (MCAO/R). The behavioral test was used to measure neurological deficit scores for evaluation of ischemic reperfusion damage of brain. The change of electroencephalograph (EEG) was monitored by Model SMUP-E Bio-electric Signals Processing System. The infarction area of brain was assessed in brain slices with 2% solution of 2,3,5-triphenyl tetrazolium chloride (TTC). Spectrophotometric assay was used to determine the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT) and lactate dehydrogenase (LDH), contents of malondialdehyde (MDA) and adenosine triphosphate (ATP) of the brain.

RESULTS

The results showed that LBP at doses of 20 and 40 mg/kg markedly decreased the neurological deficit scores and the infarction area in MCAO/R mice. At the same time, LBP significantly decreased MDA content, and increased SOD, GSH-Px, CAT, LDH activities in ischemic reperfusion brain.

CONCLUSIONS

These suggest that LBP might act as a potential neuroprotective agent against the cerebral reperfusion-induced injury in the brain through reducing lipid peroxides, scavenging free radicals, and improving the energy metabolism.

Alterations in metabolic pathways and networks in Alzheimer's disease

The pathogenic mechanisms of Alzheimer's disease (AD) remain largely unknown and clinical trials have not demonstrated significant benefit. Biochemical characterization of AD and its prodromal phase may provide new diagnostic and therapeutic insights. We used targeted metabolomics platform to profile cerebrospinal fluid (CSF) from AD (n=40), mild cognitive impairment (MCI, n=36) and control (n=38) subjects; univariate and multivariate analyses to define between-group differences; and partial least square-discriminant analysis models to classify diagnostic groups using CSF metabolomic profiles. A partial correlation network was built to link metabolic markers, protein markers and disease severity. AD subjects had elevated methionine (MET), 5-hydroxyindoleacetic acid (5-HIAA), vanillylmandelic acid, xanthosine and glutathione versus controls. MCI subjects had elevated 5-HIAA, MET, hypoxanthine and other metabolites versus controls. Metabolite ratios revealed changes within tryptophan, MET and purine pathways. Initial pathway analyses identified steps in several pathways that appear altered in AD and MCI. A partial correlation network showed total tau most directly related to norepinephrine and purine pathways; amyloid-β (Ab42) was related directly to an unidentified metabolite and indirectly to 5-HIAA and MET. These findings indicate that MCI and AD are associated with an overlapping pattern of perturbations in tryptophan, tyrosine, MET and purine pathways, and suggest that profound biochemical alterations are linked to abnormal Ab42 and tau metabolism. Metabolomics provides powerful tools to map interlinked biochemical pathway perturbations and study AD as a disease of network failure.

Abstract P4-06-21: Matrix Metalloproteinase 2 in Tumor Cell-Induced Platelet Aggregation: Regulation by Cryptotanshinone

Background: A correlation exists between the ability of tumor cells to aggregate platelets and their tendency to metastasize. Tumor cell-induced platelet aggregation (TCIPA) facilitates the embolization of the vasculature with tumor cells and the formation of metastatic foci. It is well documentedthat matrix metalloproteinases (MMPs) play an integral part in tumor spread and the metastatic cascade.

Material and Methods: Therefore, we have examined the role of MMPs during TCIPA and its regulation by Cryptotanshinone in vitro. Human breast cancer cell line MCF-7 and MDA-MB-231 induced TCIPA in a concentration dependent manner that was monitored by aggregometry. This aggregation resulted in the release of MMP-2 from platelets and cancer cells, as measured by RT-PCR.

Results:MCF-7 cells released significantly more MMP-2 than MDA-MB-231 cells and were more efficacious in inducing TCIPA. Inhibition of MMP-2 with phenanthroline (1-1000 mM), a synthetic inhibitor of MMPs, and by neutralizing anti-MMP-2 antibody (10 mg/ml) reduced TCIPA induced by MCF-7 cells. TCIPA was abolished by simultaneous inhibition of platelet function with acetylsalicylic acid (100 mM; thromboxane pathway inhibitor), apyrase (250 mg/ml; ADP pathway inhibitor), and phenanthroline. Cryptotanshinone inhibited TCIPA and MMP-2 release from platelets and tumor cells.

Discussion:We conclude that (a) human Human breast cancer cells aggregate platelets via mechanism (s) that are mediated, in part, by MMP-2; (b) Cryptotanshinone inhibits TCIPA, in part, by attenuating the release of MMP-2.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P4-06-21.

Downregulation of Kv4.2 channels mediated by NR2B-containing NMDA receptors in cultured hippocampal neurons

Somatodendritic Kv4.2 channels mediate transient A-type potassium currents (I(A)), and play critical roles in controlling neuronal excitability and modulating synaptic plasticity. Our studies have shown an NMDA receptor-dependent downregulation of Kv4.2 and I(A). NMDA receptors are heteromeric complexes of NR1 combined with NR2A-NR2D, mainly NR2A and NR2B. Here, we investigate NR2B receptor-mediated modulation of Kv4.2 and I(A) in cultured hippocampal neurons. Application of glutamate caused a reduction in total Kv4.2 protein levels and Kv4.2 clusters, and produced a hyperpolarized shift in the inactivation curve of I(A). The effects of glutamate on Kv4.2 and I(A) were inhibited by pretreatment of NR2B-selective antagonists. NR2B-containing NMDA receptors are believed to be located predominantly extrasynaptically. Like application of glutamate, selective activation of extrasynaptic NMDA receptors caused a reduction in total Kv4.2 protein levels and Kv4.2 clusters, which was also blocked by NR2B-selective antagonists. In contrast, specific stimulation of synaptic NMDA receptors had no effect on Kv4.2. In addition, the influx of Ca(2+) was essential for extrasynaptic modulation of Kv4.2. Calpain inhibitors prevented the reduction of total Kv4.2 protein levels following activation of extrasynaptic NMDA receptors. These results demonstrate that the glutamate-induced downregulation of Kv4.2 and I(A) is mediated by NR2B-containing NMDA receptors and is linked to proteolysis by calpain, which might contribute to the development of neuronal hyperexcitability and neurodegenerative diseases.

Clinical study of mini-nutritional assessment for older Chinese inpatients

BACKGROUND

Malnutrition is a common problem in older patients. Early detection of malnutrition is an important task in clinical practice. The MNA has become an extensively used tool to evaluate nutritional status in European countries and the United States.

OBJECTIVE

We evaluated the Mini-Nutritional Assessment (MNA) test and the short-form MNA (MNA-SF) test as screening tools for malnutrition in older Chinese inpatients and focused on finding an optimal cutoff point for MNA total score and MNA-SF score.

DESIGN

One hundred eighty-four older Chinese inpatients were enrolled in this study from July to August 2006. Nutritional assessment included MNA, anthropometric measurements, and biochemical markers.

RESULTS

According to the original cutoff point of the full MNA, 19.6% of those assessed were malnourished, 53.2% were at risk of malnutrition and 27.2% were well nourished. Correlations were found between MNA, MNA-SF and body mass index, triceps skinfold thickness, serum albumin, lymphocyte count, hemoglobin, lymphocyte ratio. With the most proper cutoff point lower than 19 indicating malnutrition, when using serum albumin (< 35.0 g/L) as the indicator, the sensitivity and specificity of the MNA total score were 0.6286 and 0.7466; when using BMI (< 18.5 kg/m2) as the indicator, the sensitivity and specificity were 0.8636 and 0.7469. The incidence rate of malnutrition was 32.6%. The most proper cutoff point of MNA-SF was lower than 12.

CONCLUSION

The MNA and MNA-SF were useful tools to identify older Chinese inpatients with malnutrition. However, the cutoff point of the MNA should be modulated for this population.

dRecQ4 is required for DNA synthesis and essential for cell proliferation in Drosophila

BACKGROUND

The family of RecQ DNA helicases plays an important role in the maintenance of genomic integrity. Mutations in three of the five known RecQ family members in humans, BLM, WRN and RecQ4, lead to disorders that are characterized by predisposition to cancer and premature aging.

METHODOLOGY/PRINCIPAL FINDINGS

To address the in vivo functions of Drosophila RecQ4 (dRecQ4), we generated mutant alleles of dRecQ4 using the targeted gene knock-out technique. Our data show that dRecQ4 mutants are homozygous lethal with defects in DNA replication, cell cycle progression and cell proliferation. Two sets of experiments suggest that dRecQ4 also plays a role in DNA double strand break repair. First, mutant animals exhibit sensitivity to gamma irradiation. Second, the efficiency of DsRed reconstitution via single strand annealing repair is significantly reduced in the dRecQ4 mutant animals. Rescue experiments further show that both the N-terminal domain and the helicase domain are essential to dRecQ4 function in vivo. The N-terminal domain is sufficient for the DNA repair function of dRecQ4.

CONCLUSIONS/SIGNIFICANCE

Together, our results show that dRecQ4 is an essential gene that plays an important role in not only DNA replication but also DNA repair and cell cycle progression in vivo.

Feeding, oviposition and survival of Liriomyza trifolii (Diptera: Agromyzidae) on Bt and non-Bt cottons

The effects of Bt transgenic cottons (Bt-I expressing cry1Ac and Bt-II expressing cry1Ab and cry2Ab or cry1Ab and cry1Fa) and non-Bt cottons on feeding, oviposition and longevity of adults, and development and survival of Liriomyza trifolii larvae were studied under laboratory conditions; and infestation on four Bt and two non-Bt cotton traits were investigated under field conditions. Laboratory choice and no-choice tests showed that L. trifolii adults were capable of distinguishing between Bt cottons and non-Bt cottons. In a choice test on younger plants (4-5 leaves), the adults were found more often and made more feeding punctures (FP) on non-Bt cottons than on Bt cottons. On older plants (8-9 leaves), adults made the most FP on non-Bt cotton followed by those on Bt-II cottons and the least on Bt-I cotton. The females oviposited more eggs (6.7 eggs per leaf) on non-Bt cotton than on Bt-I (1.7 eggs per leaf) and Bt-II (0.8 eggs per leaf) cottons on younger plants and oviposited similar numbers of eggs (0.7-1.3 eggs per leaf) on non-Bt and Bt cottons on older plants. In a no-choice test, the females also fed more FP on non-Bt cottons than on Bt cottons on both younger and older plants. The females oviposited more eggs (15.6 eggs per leaf) on non-Bt cotton than on Bt-I (8.2 eggs per leaf) and Bt-II (6.5 eggs per leaf) cottons on younger plants and similar numbers of eggs (2.5-3.3 eggs per leaf) on non-Bt and Bt cottons on older plants. Larval and puparial survivals were not different among Bt and non-Bt cottons. The occurrence and damage of leafminers on cottons in the field showed that L. trifolii infested more plants and leaves and had more mines on non-Bt cotton than on Bt cottons.

Enhancement of inhibitory synaptic transmission in large aspiny neurons after transient cerebral ischemia

Large aspiny neurons and most of the GABAergic interneurons survive transient cerebral ischemia while medium spiny neurons degenerate in 24 h. Expression of a long-term enhancement of excitatory transmission in medium spiny neurons but not in large aspiny neurons has been indicated to contribute to this selective vulnerability. Because neuronal excitability is determined by the counterbalance of excitation and inhibition, the present study examined inhibitory synaptic transmission in large aspiny neurons after ischemia in rats. Transient cerebral ischemia was induced for 22 min using the four-vessel occlusion method and whole-cell voltage-clamp recording was performed on striatal slices. The amplitudes of evoked inhibitory postsynaptic currents in large aspiny neurons were significantly increased at 3 and 24 h after ischemia, which was mediated by the increase of presynaptic release. Postsynaptic responses were depressed at 24 h after ischemia. Inhibitory postsynaptic currents could be evoked in large aspiny neurons at 24 h after ischemia, suggesting that they receive GABAergic inputs from the survived GABAergic interneurons. Muscimol, a GABA(A) receptor agonist, presynaptically facilitated inhibitory synaptic transmission at 24 h after ischemia. Such facilitation was dependent on the extracellular calcium and voltage-gated sodium channels. The present study demonstrates an enhancement of inhibitory synaptic transmission in large aspiny neurons after ischemia, which might reduce excitotoxicity and contribute, at least in part, to the survival of large aspiny neurons. Our data also suggest that large aspiny neurons might receive inhibitory inputs from GABAergic interneurons.

Ensuring the safety of living kidney donors and recipients in China through ethics committee oversight: an early experience

In 2007, the Regulation on Human Organ Transplantation was enacted in China requiring the establishment of ethics committees to oversee living donor organ transplantation and establishing specific requirements that must be met. We established an Ethics Committee on Organ Transplantation at Peking University Third Hospital, and described its composition, its methods and operating procedures in the examination and approval of living-related donor kidney transplantation (LRDKT) and our initial experience. All 60 proposed cases of LRDKT were presented to the Ethics Committee for discussion, among which 53 cases were approved and seven cases were disapproved due to a variety of reasons that are discussed. The Ethics Committee on Organ Transplantation plays an important role in the ethical oversight of living-related donor organ transplantation in order to ensure to the greatest extent possible the safety, rights and interests of donors and recipients.