Volume 113  ·   Issue 10  ·  2000

Purpose To identify the structure and the function of NMDA receptors, to understand the modulatory mechanism of some endogenous and exogenous compounds on NMDA receptors, and to provide theoretical basis for developing new drugs that modulate NMDA receptors. Data sources A total of 24 originally identified articles were selected. Study selection A total of 24 articles were selected from several hundred original articles or reviews. The content of selected articles are in accordance with our purpose and the authors are authorized scientists in the study on NMDA receptors. Data extraction After careful review of the selected papers, the meaningful results and conclusions were extracted using scientific criteria and our experience in the research of NMDA receptors. Results NMDA receptor contains at least five subunits. They were designated as the NR1(ζ1), NR2A(ε1), NR2B(ε2), NR2C(ε3), and NR2D(ε4). A unique feature of NMDA receptor is the requirement for both glutamate and the co-agnist glycine for the efficient gating. NMDA receptor is modulated by a number of endogenous and exogenous compounds. Mg2+ not only blocks the NMDA channel in a voltage-dependent manner but also potentiates NMDA-induced responses at positive membrane potentials. Na+, K+ and Ca2+ not only pass through the NMDA receptor channel but also modulate the activity of NMDA receptors. Zn2+ blocks the NMDA current in a noncompetitive and a voltage-independent manner. It has been demonstrated that polyamines do not directly activate NMDA receptors, but instead act to potentiate or inhibit glutamate-mediated responses. The activity of NMDA receptors is also strikingly sensitive to the changes in H+ concentration, and partially inhibited by the ambient concentration of H+ under physiological conditions. Conclusions NMDA receptors are glutamate-regulated by ion channels that are permeable to Ca2+, Na+, K+ and are sensitive to voltage-dependent Mg2+ block. This channel complex contributes to excitatory synaptic transmission at sites throughout the brain and the spinal cord, and is modulated by a number of endogenous and exogenous compounds. NMDA receptors play a key role in wide range of physiologic and pathologic processes. Five NMDA receptor subunits have now been characterized in both rat and mouse brain. Chin Med J 2000; 113(10): 948-956

Purpose To review the major achievements of biological products of China in the scientific research and development. Data sources The contents of this article were selected from the original essays or reviews related to biologicals published in Chinese and foreign journals. Study selections Briefly original articles and reviews of text books published by Chinese authors in the last twenty yars were selected. Date extraction These data have addressed the novel vaccines and engineering genetic technologies on biologicals. Results Nowadays about 200 kinds of biological products are produced in China ranging from preventive vaccines as the majority to therapeutic and diagnostic products. About 800-900 million doses of vaccines for the purpose of prophylaxis are administered annually. Biologicals have played an important role in the prevention of infectious diseases. During the former 30 years the basis for the further development of research work was set up and in the latter 20 years new achievements were made one after another, for example, the development of attenuated JE vaccine, hepatitis A live vaccine, HFRS inactivated vaccine, recombinant HB vaccine and Vi typhoid vaccine, et al. Conclusion During the past 50 years, China has made a great progress in the field of biological products, however we are still week in the aspect of basis research and backward behind the developed countries in originating new products. Chin Med J 2000; 113(10): 942-947

Objective Superantigens are potent inflammatory stimuli which derive from pathogenic microbes such as bacteria, viruses and protozoa. The aim of this study was to investigate the role of superantigens on the function of rabbit maxillary sinus epithelium. Methods Twenty New Zealand white rabbits were divided into 4 groups. Rabbit sinus mucosa was separated under a surgical microscope and mounted in Ussing chambers to record short circuit current, conductance and permeability to horseradish peroxidase(HRP). Group A was used as normal control. Group B was stimulated with an injection of superantigen into the sinus for 4 hours. The sinus mucosa of Group C was stimulated by the addition of tumor necrosis factor a(TNF-α)into Ussing chambers. Group D sinus mucosa was stimulated by superantigen after pretreatment with anti-TNF-α antibody. Results Superantigen evoked increases in sinus epithelial cell baseline short circuit current, conductance and permeability to HRP stimulated by the addition of TNF-α into Ussing chambers. These were similar to results from superantigen stimulation in vivo. The effect of superantigen on sinus epithelial cells could be blocked by pretreatment with anti-TNF-α antibody. Conclusions Superantigen affected the function of sinus epithelial cells, including the capability of epithelial defensive barrier, which might be mediated by TNF-α. Chin Med J 2000; 113(10): 938-941

Objective To study the lymphocytes, perforin protein and mRNA expression in endometrium of different phases in the menstrual cycle and to explore the regularity and role of the lymphocytes and perforin in the reproductive system. Methods Immunohistochemical and in situ hybridization techniques were employed to demonstrate the population, phenotype and mediator(perforin)of lymphocytes in the proliferative and secretory endometrium. Results In different phases of the endometrium, there were very few CD3+ typical T lymphocytes, CD4+ helper lymphocytes and CD8+ suppressor/cytotoxic T lymphocytes, while CD56+. lymphocyte(also named NK-like cell)were abundant. CD56+ lymphocytes were absent in postmenopausal endometrium. A double immunohistochemical labelling method demonstrated the co-expression of perforin protein and CD56 antigen of cells in different phases of the endometrium. Quantitative analysis of CD56+ lymphocytes and perforin-positive cells increased in number from the proliferative to the secretory endometrium(P < 0.05). In situ hybridization analysis showed that perforin mRNA positive cells formed islands in proliferative endometrial stroma, but were scattered in secretory endometrium. There was difference between perforin gene expression and protein expression in the proliferative endometrium. Conclusions Lymphocytes and perforin expression in the endometrium at different phases of the menstrual cycle are specific and may play an important role in the reproductive system. They may exert a positive influence on embryo implantation and be involved in endometrial stroma breakdown during menstruation. Chin Med J 2000; 113(10): 930-933

Objective To study the methods of interventional treatment of huge hepatic cavernous hemangioma(HCH). Method A total of 14 patients with HCH were treated with lipiodol-ultrafluid(10-15 ml), bleomycin A(PYM 16-32 mg), and gelatin-sponge particles. Results DSA hepatic arteriography showed multiple vascular lakes in the early arterial phase, so-called"to hang the fruits on the branches", which persisted for a long time. CT scan showed a significant reduction in tumor size in 8 of the 14 patients after the treatment. Conclusion Embolization with lipiodol-ultrafluid, PYM and gelatin sponge particles is one of the best methods for the treatment of HCH. Chin Med J 2000; 113(10): 927-929

Objective To assess the value of noninvasive three-dimensional computed tomographic angiography(3D-CTA)in preoperative detection of intracranial arteriovenous malformations(AVMs). Methods A prospective evaluation at a single institute over a 2-year period included 23 patients suspected of intracranial AVMs. All patients underwent 3D-CTA and digital subtraction angiography(DSA). Results from both procedures were compared. Results 3D-CTA imaging provided excellent visualization of intracranial AVMs. The false positive error and false negative error were zero in our sample. The details of arterial supply(numerical measure, orientation, caliber and routing)and vascular nidus(size, morphosis and location)provided by 3D-CTA images were the same as DSA and the details of venous drainage were an approximate match. Additionally, 3D-CTA can depict tridimensional anatomical information for AVMs and their relationship to adjacent structures, a function not possible with DSA. This assisted the surgeons in making better surgical planning and reduced trauma. As a noninvasive course, there were no related-complications in the course of 3D-CTA processing. Conclusions DSA is still regarded as the gold standard for intracranial AVMs detection. The modality of 3D-CTA is accurate, noninvasive, nearly risk free and low-price; we could routinely use it instead of or as a supplement to DSA, in the preoperative detection of suspected intracranial AVMs and postoperative radiological follow-up. 3D-CTA adds tridimensional aspect and assists the surgeon in a the more accurate therapeutic scheme. Preliminary data suggest that 3D-CTA is playing a favorable role in the assessment of patients with intracranial AVMs. Chin Med J 2000; 113(l0): 915-920

Objective To assess the genotoxic effects of X-ray radiation on human populations. Methods The single cell gel electrophoresis(SCGE)and cytokinesis-blocked micronucleus(CBMN)test were applied as biological dosimeters to detect DNA damage and abnormalities in human peripheral lymphocytes of subpopulation exposed to X-ray radiation. The subjects were divided into four groups: 12 radiation-patients; 13 intervention-radiation-therapy doctors; 32 radiation-diagnostians; 28 controls. Results The average comet lengths of the four groups were 128.17 ± 4.49 μm, 88.09 ± 5.39 μm, 72.68 ± 2.57 μm and 2.87 ± 0.57 μm, respectively. The difference in average comet length between any two groups was highly significant(P < 0.01). The average micronucleated cell(MNC)rates(‰)of the four groups were 12.33±0.85, 9.75±1.02, 8.48 ± 0.66 and 3.18±0.36, respectively. The difference of MNC rates of Group 1 vs 3, 1 vs 4, 2 vs 4 and 3 vs 4 was highly significant(P < 0.01), and the difference of Group 1 vs 2 was significant(P < 0.05), but there was no difference of MNC rate in Group 2 vs 3(P > 0.05). Conclusions This study showed that both the comet assay and the CBMN test could be used to monitor populations exposed to X-ray radiation, but the comet assay seems to be more sensitive than the CBMN test. Chin Med J 2000; 113(10): 911-914

Objective To investigate the cellular immune mechanism of thyroid associated ophthalmopathy(TAO)and provide a basis for treating TAO with cytokine or anti-cytokine agents, we determined whether interferon(IFN)-γ and interleukin(IL)-4, representative cytokines of Th1 and Th2 cells, may have some effect on the development and progression of TAO. Method Retroorbital fibroblasts(RF)proliferation and the synthesis of hyaluronic acid(HA)and type IV collagen were measured with liquid scintillation and radioimmunoassay. Results IFN-γ stimulated RF proliferation and HA synthesis and had a significant inhibitory effect on type IV collagen synthesis. IL-4 stimulated proliferation and type IV collagen synthesis in RF and had inhibitory effect on HA synthesis. When IFN-γ(100 U/ml)and IL-4(1 μg/L)were incubated together with RF, they antagonized their respective stimulatory or inhibitory effect on the proliferation and synthesis of HA and type IV collagen. Thyrotropin(TSH)stimulated RF proliferation and type IV collagen synthesis in a dose-dependent manner, while only at high dose(100 U/L and 200 U/L), stimulated RF to synthesize HA. Conclusions IFN-γ, a representative cytokine of Th1 cells, is responsible for the inflammatory process of TAO; whereas IL-4, a representative cytokine of Th2 cells, has some effect on the repair process. IL-4 could antagonize the inflammatory effect of IFN-γ on RF. TSH may have aggravating effect on the pathogenesis of TAO. Chin Med J 2000; 113(10): 907-910

Objective To study the effects of high concentrations of glucose, insulin and oxidized low density lipoprotein(ox-LDL)on apoptosis in cultured bovine aortic endothelial cells(ECs). Methods For qualitative determination of EC apoptosis, acridine orange(AO)/ethidium bromide(EB)staining and DNA agarose gels electrophoresis were used. Cellular DNA fragmentation ELISA measured apoptosis by quantitating the fragmentation of 5-bromo-2'-deoxyuridine-labeled DNA. Results High concentrations of glucose(20 mmol/L, 40 mmol/L), insulin(3000 μU/ml)and ox-LDL(50μg/ml, 100 μg/ml)induced concentration-and time-dependent apoptosis in ECs. They had a synergetic effect on EC apoptosis. The combined effect of high concentration of glucose, insulin and ox-LDL was greater than any two of them; the effect of two was greater than one alone. Low concentration of insulin(30 μU/ml)decreased apoptosis in ECs induced by high concentrations of glucose(40 mmol/L), but no similar effect occurred with ox-LDL(100 μg/ml). Conclusion High ambient glucose, insulin and ox-LDL can induce excessive apoptosis in cultured ECs, and low ambient insulin can prevent EC apoptosis. Excessive EC apoptosis induced by the separate or synergetic effect of hyperglycemia, hyperinsulinemia and hyperlipidemia may be one of the reasons for loss of endothelial integrity, dysfunction of the vascular endothelium and increased plasma membrane permeability, which are all involved in the development of diabetic macrovascular complications. Chin Med J 2000; 113(l0): 903-906

Objective To evaluate the impact of kinetics of molecular remission via retro-transcriptase polymerase chain reaction(RT-PCR)assay on the long-term survival in patients with acute promyelocytic leukemia(APL). Methods Seventy patients with newly-diagnosed APL in remission were involved in this study. Monitoring of minimal residual disease(MRD)was performed regularly by RT-PCR assay for PML-RARα during consolidation. Results A 5-year relapse-free survival(RFS)and overall-survival(OS)were estimated as 46.8% ± 8.4% and 69.9%±9.4% for the whole group. Fifty-two(74.3%)patients got negative RT-PCR result at least once. Serial monitoring of RT-PCR was available in 38 cases and 24(63.2%)patients presented with persistent negative PGR results. The achievement and continuous negative RT-PCR result was significantly related to the RFS. Conclusions Achievement of negative RT-PCR in remission is associated with favorable RFS and OS. Continuous negative RT-PCR results are associated with long-term relapse-free survival and may be considered as potentially curative. RT-PCR assay for detection of MRD should be performed regularly during post-remission period as an important prognostic factor. Chin Med J 2000; 113(10): 899-902

Objective To isolate genes related to blood glucose-control using Sprague Dawley(SD)rat skeletal muscle. Methods Differential gene expression between glucose stimulated and non-glucose stimulated SD rat skeletal muscle was obtained by the differential display(DD)method, Slot blotting hybridization and Northern blot hybridization. Results Several new genes that are differentially expressed in glucose stimulated and non-glucose stimulated SD rat skeletal muscle were isolated. 74 were verified by slot analysis from 181 gene tags isolated. Of them, 33 were cloned and sequenced, and homologous analysis and application for GenBank Access Number were carried out. 21 expressed sequence tag(EST)representing novel genes was confirmed by Northern blot analysis. A total of 9 novel genes showed significant differential expression patterns. Conclusions Using improvements and modifications of the differential display technique, a labor-and cost-saving route was used to identify new genes related to blood glucose-control. We investigated differentially expressed genes at the whole body level instead of the culture cell level, to ensure experimental results closer to the normal physiological state. This technique may be valid in wide-spread application to other related research. Chin Med J 2000; 113(l0): 894-898

Objective To determine whether p16 gene is involved in the genesis of primary hepatocellular carcinoma(HCC). Methods Twenty-five HCC tumor samples with corresponding non-tumor liver tissue specimens were examined for p16 gene alterations. The identification of deletion of exon 1 and exon 2 in p16 gene was performed using comparative multiplex polymerase chain reaction(PCR)analysis. The point mutation of exon 2 in p16 gene was investigated by single strand conformational polymorphism(SSCP)analysis, and the status of p16 gene methylation was screened using a PCR based methylation analysis. 35 parafin-embedded specimens of HCC with corresponding nontumor liver tissues, including the 25 cases described above for screening p16 gene alterations, were investigated for p16 protein expression using immunohistochemical analysis. Results Among 25 cases, 2 homozygous deletions and 1 hemizygous deletion were found in HCC samples. No point mutation was identified in the remaining 22 tumor samples without p16 gene deletions. Hypermethylation was detected in 24%(6/25)of tumor samples. However, the corresponding non-tumor liver tissue specimens were always unmethylated at the p16 locus. Loss of p16 protein expression occurred in 16 of 35(45.7%)tumor samples, and all the non-tumor liver tissue specimens showed positive p16 staining. For the 25 cases examined for p16 gene alterations, the loss of p16 protein expression was observed in all tumors with p16 gene alterations and also in 3 tumors without p16 gene alterations. Conclusion Inactivation of the p16 gene may play an important role in the genesis of primary hepatocellular carcinoma. Chin Med J 2000; 113(10): 889-893

Objective To detect the influence of antisense s-oligodeoxynucleotides(S-ODNs)of bd-2 and multidrug resistamce-associated protein(MRP)genes multidrug resistance-associated protein gene and bcl-2 antisense S-oligodeoxynucleotides on cisplatin-resistant lung adenocarcinoma cell line A549DDP which overexpresses both bcl-2 and MRP. Methods A549DPP cells were treated with sense and antisense S-ODN mediated by lipofection. Expression of MRP and bcl-2 mRNA and protein in the treated cells was measured by RT-PCR and flow cytometry(FCM), respectively. Apoptosis was identified by DNA electrophoresis and terminal deoxynucleotidyl transferase(TdT)-mediated biotin dUTP nick end-labeling(TUNEL). The degree of drug resistance of the treated cells was detected by a cell viability 3'-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyl-tefrazolium bromide thiazolylblue(MTT)assay. Results Expression of bcl-2 and MRP significantly decreased in the cells treated with bcl-2 or/and MRP antisense S-ODN for 48h as compared to the cells untreated and sense-treated(P < 0.05). Resistance to cisplatin in the cells treated with bcl-2 or/and MRP antisense S-ODN decreased by 60.6%(6.5 times), 56.4%(7.2 times)and 71.0%(4.8 times), respectively, which paralleled the decrease of bcl-2 and MRP expression. Similarly, the resistance to etoposide and epirubicin in antisense-treated cells also reduced in parallel to decreases of the two gene expressions. The drug resistance in sense-treated cells was similar to that in untreated cells. Statistically significant dose-and concentration-dependent increases of apoptotic cells were observed in the groups exposed to 100 μmol/L cisplatin for 48 h after treatment by bcl-2 or/and MRP antisense. Conclusion Bcl-2 and MRP were at least additive and possibly synergistic in conferring drug resistance in a cisplatin-resistant lung adenocarcinoma cell line. Antisense S-ODN could attenuate drug resistance by promoting cells apoptosis, which might lead to a new treatment for patients with non-small cell lung cancers(NSCLCs)who are refractory to conventional chemotherapy. Chin Med J 2000; 113(10): 957-960