Showing papers by "Hong Liu published in 2000"

[The expression of glial cell derived neurotrophic factor and its receptor GDNFR-alpha and GDNFR-beta mRNA in spinal cord, brainstem and frontal cortex during morphine withdrawal in rats].

Abstract: Objective To investigate the expression of glial cell derived neurotrophic factor (GDNF) and its receptor GDNFR-alpha (GFRalpha-1) and GDNFR-beta (Ret) genes and the effects of muscarinic receptor antagonists, NMDA receptor antagonist, inhibitor of nitric oxide synthase on the expression of these genes in the spinal cord, brainstem and frontal cortex during morphine withdrawal, and to observe the effects of GDNF antisense oligoneucleotide (i.c.v) on the morphine withdrawal symptoms in rats. Methods The levels of GDNF, GDNFR-alpha and GDNFR-beta mRNA were assayed by reverse transcription polymerase chain reaction (RT-PCR) with the beta-actin mRNA as an internal control. Results The GDNF mRNA levels were increased, and GDNFR-alpha and GDNFR-beta mRNA levels was slightly increased in the spinal cord and brainstem during morphine dependence. These genes were decreased at 1 h, increased at 2 h after administration of naloxone in morphine dependent rats. While the GDNF, GDNFR-alpha and GDNFR-beta levels in the frontal cortex were increased significantly at 1, 2 and 4 h after the injection of naloxone during morphine withdrawal. The pre-treatment with L-N-nitric arginine methylester (10 mg/kg), the expressions of GDNF and GDNFR-beta in the spinal cord, both GDNFR-alpha and GDNFR-beta in the frontal cortex were decreased. The expressions of both GDNF and GDNFR-alpha in the frontal cortex were decreased by treatment with MK801 (0.5 mg/kg), and the expressions of GDNF in both the stem and cortex, and GDNFR-beta in the brainstem decreased by treatment with the methyl-scopolamine (0.5 mg/kg). The beta-actin mRNA levels were not different in each group. Moreover, the morphine withdrawal symptoms were attenuated by intracerebroven tricular injection of GDNF antisense oligoneucleotide in 6 hour and 24 hour before naloxone administration in morphine dependent rats. Conclusion The results not only provide direct evidence that the expressions of GDNF and its receptors mRNA in glial cells play an important role in mediating the process of morphine dependence and may be account for the long-term neuro-adaptation associated with morphine dependence, but also suggest that muscarinic receptor, NMDA receptor and nitric oxide pathways may be involved in the expression of GDNF and GDNF receptor genes during morphine withdrawal.

Construction of compactly supported biorthogonal wavelet based on Human Visual System

Abstract: As an important analysis tool, wavelet transform has made a great development in image compression coding, since Daubechies constructed a kind of compact support orthogonal wavelet and Mallat presented a fast pyramid algorithm for wavelet decomposition and reconstruction. In order to raise the compression ratio and improve the visual quality of reconstruction, it becomes very important to find a wavelet basis that fits the human visual system (HVS). Marr wavelet, as it is known, is a kind of wavelet, so it is not suitable for implementation of image compression coding. In this paper, a new method is provided to construct a kind of compactly supported biorthogonal wavelet based on human visual system, we employ the genetic algorithm to construct compactly supported biorthogonal wavelet that can approximate the modulation transform function for HVS. The novel constructed wavelet is applied to image compression coding in our experiments. The experimental results indicate that the visual quality of reconstruction with the new kind of wavelet is equivalent to other compactly biorthogonal wavelets in the condition of the same bit rate. It has good performance of reconstruction, especially used in texture image compression coding.

Very low bit-rate video coding using a new kind of compact biorthogonal wavelet

Abstract: Video communication aiming at public switched telephone network (PSTN) applied with voice-band modem is attractive because of its low-cost facilities and the wide coverage of PSTN around the world, The key technique of video transmission over PSTN with voice-band modem is very low bit-rate video coding. Video coding based on discrete wavelet transform has become a hot research topic. But while in very low bit-rate video coding applications, the peak signal to noise ratio (PSNR) and the visual quality of image reconstructions are not very satisfactory by using the general orthogonal or biorthogonal wavelet which does not match well with human visual system characteristics. In this paper, a new kind of compact biorthogonal wavelet based on the modulation transfer function for human visual system model is used in very low bit-rate video coding scheme, in which a new improved Goh's 3D wavelet transform and motion compression technique are applied. The experimental results indicate that the new coding scheme using the constructed compact biorthogonal wavelet has a good performance in average PSNR, compression ratios and visual quality of image reconstruction when compared to the other motion-compensated 2D and 3D coding schemes based on the general biorthogonal wavelet transform.

Estrogen receptor gene polymorphism and its association with clinicopathological manifestation of lupus nephritis

Abstract: OBJECTIVE To investigate the distribution of estrogen receptor (ER) in patients with lupus nephritis (LN), and the association between ER gene polymorphism and the clinical and pathological features of the disease. METHODS The Pvu II and Xba I restriction fragment length polymorphism (RFLP) of estrogen receptor gene were analyzed in 245 biopsy proven LN patients (58 males and 187 females) and 172 normal controls(101 males and 71 females) by PCR-RFLP. The clinical and pathological features of 49 male and 152 female LN patients with genotype PpXx or Ppxx, ppxx were then analyzed respectively. RESULTS It was found that genotype PpXx and ppxx, Ppxx were three major genotypes of ER gene in both lupus patients group and control group. The distribution of ER gene polymorphism was quite different in lupus patients of different genders. The frequency of the PpXx genotype was significantly higher in male LN patients than in both the gender matched normal controls (P<0.05) and the female LN patients (P<0.05), while no difference was shown in the frequency of PpXx genotype between female LN patients and female controls. Interestingly, varied clinical and renal pathological features were also demonstrated in female patients with different genotypes of ER gene. CONCLUSION The distribution of ER gene polymorphism in LN patients varies with gender. The PpXx genotype of ER gene may be associated with the susceptibility of LN in male. ER gene polymorphism is probably one of the genetic factors contributing to the development of clinical heterogeneity and sexually dimorphic manifestations of LN.