Origin of the Surprising Mechanical Stability of Kinesin's Neck Coiled Coil

Kinesin-1 is a motor protein moving along a microtubule with its two identical motor heads dimerized by two neck linkers and a coiled-coil stalk. When both motor heads bind the microtubule, an internal strain is built up between the two heads, which is indispensable to ensure proper coordination of the two motor heads during kinesin-1's mechanochemical cycle. The internal strain forms a tensile force along the neck linker that tends to unwind the neck coiled coil (NCC). Experiments showed that the kinesin-1's NCC has a high antiunwinding ability compared with conventional coiled coils, which was mainly attributed to the enhanced hydrophobic pressure arising from the unconventional sequence of kinesin-1's NCC. However, hydrophobic pressure cannot provide the shearing force which is needed to balance the tensile force on the interface between two helices. To find out the true origin of the mechanical stability of kinesin-1's NCC, we perform a novel and detailed mechanical analysis for the system based on molecular dynamics simulation at an atomic level. We find that the needed shearing force is provided by a buckle structure formed by two tyrosines which form effective steric hindrance in the presence of tensile forces. The tensile force is balanced by the tensile direction component of the contact force between the two tyrosines which forms the shearing force. The hydrophobic pressure balances the other component of the contact force perpendicular to the tensile direction. The antiunwinding strength of NCC is defined by the maximum shearing force, which is finally determined by the hydrophobic pressure. Kinesin-1 uses residues with plane side chains, tryptophans and tyrosines, to form the hydrophobic center and to shorten the interhelix distance so that a high antiunwinding strength is obtained. The special design of NCC ensures exquisite cooperation of steric hindrance and hydrophobic pressure that results in the surprising mechanical stability of NCC.

[Quick Start-up Performance of Combined ANAMMOX Reactor Based on Different Inoculated Sludge Types]

In order to determine the optimal sludge source of anaerobic ammonium oxidation (ANAMMOX) and the rapid formation of ANAMMOX granular sludge, two CAMBRs (combined ABR and MBR) were compared for ANAMMOX enrichment with different inoculated sludge types, the anaerobic granular sludge (R1) and flocculent denitrifying sludge (R2). The results showed that ANAMMOX was successfully initiated after 45 d (R1) and 60 d (R2) in both reactors, respectively. The enrichment processes are divided into three different phases, lag phase, activity elevation phase, and stationary phase but the removal rules of nitrogen in each phase were different. In the steady phase, the average removal rates of NH₄⁺-N and NO₂^--N were higher than 95%. In addition, the red ANAMMOX granular sludge with the main diameter of 0.8-1.6 mm was formed in R1 while the flocculent sludge and irregular block with a low degree of granulation were mainly developed in R2. The phenomenon of red granular sludge floating in the two reactors was also observed. The quantitative relationship analysis between NH₄⁺-N, NO₂-N, and NO₃^--N showed the occurrence of nitrate-dependent ANAMMOX, which resulted in the oxidation of excess ammonia and the typical nitrite-dependent ANAMMOX occurred in R2.

[Fast Start-up of Shortcut Nitrification in a CSTR and an MBR]

In order to achieve fast start-up of shortcut nitrification, a continuous stirred tank reactor (CSTR) and a membrane bioreactor (MBR) were selected for a comparative study about the start-up characteristic of shortcut nitrification. The differences in three aspects of the two reactors were investigated, namely start-up time, nitrogen transformation, and sludge performance. The results showed that the start-up of shortcut nitrification was successfully achieved in the CSTR and MBR after 44 and 56 days of operation, respectively, with influent C/N=1, temperature around 30℃±1℃, pH of 7.5-8.0, and dissolved oxygen (DO) of 0.6-1.0 mg·L^-1, as well as combining anoxic/aerobic ratio 1:3 (15 min:45 min) with shortened hydraulic retention time (HRT). The start-up period of the MBR was shorter. On the 14th, 28th, and 56th day, the average nitrite accumulation efficiencies in the CSTR were 51%, 66%, and 89%, respectively, and 50%, 71%, and 93% in the MBR, and nitrate formation rates of the CSTR was successively 7.4, 4.0, and 1.7 mg·(g·h)^-1 (NO₃^--N/MLVSS), respectively, and 7.6, 3.5, and 1.0 mg·(g·h)^-1 (NO₃^--N/MLVSS) for the MBR. A higher nitrite accumulation efficiency and a lower nitrate formation rate were detected in the MBR on the 28th and 56th day, respectively, which could be beneficial to the fast start-up of shortcut nitrification. During the operation period, the shortcut nitrification sludge in the two reactors was yellow, the sludge volume index (SVI) was between 55 and 110 mL·g^-1, and the mixed liquor volatile suspended solids (MLVSS)/mixed liquor suspended solids (MLSS) ratio was around 0.6-0.8. The good sludge performance created favorable conditions for the fast start-up of shortcut nitrification in both the CSTR and MBR. In conclusion, the MBR exhibited better performance in the fast start-up of shortcut nitrification.

[Effect of Substrate Ratio on Nitrogen Removal Performance of ANAMMOX in ABR]

In order to solve the problem of low nitrogen removal caused by incomplete removal of anaerobic ammonium oxidation (ANAMMOX) substrate, The nitrogen removal performance of the ANAMMOX was investigated by controlling different influent substrate ratios in an anaerobic baffled reactor (ABR). The result showed the optimal influent NO₂^--N/NH₄⁺-N was 1.34 with which the NH₄⁺-N and NO₂^--N removal efficiencies were about 99.99% and the total nitrogen removal efficiency reached a peak of 87%. When the influent NO₂^--N/NH₄⁺-N gradually reduced from 1 to 0.49 and increased from 1.34 to 1.62, the absolute removal of NH₄⁺-N and NO₂^--N was stable in the reactor and no significant inhibition was observed in the system. Under the condition of different substrate ratios, the removal of NH₄⁺-N and NO₂^--N was basically consumed in the first compartment of ABR, the change of substrate ratio did not have an obvious impact on the nitrogen removal performance of each compartment in the ABR, thus, the ABR ANAMMOX system had good stability to the change of substrate concentration.

[Quick Start-up of Anaerobic Ammonium Oxidation Process]

In order to study the quick start-up process of anaerobic ammonium oxidation (ANAMMOX), two types of reactors with different hydraclic flow state inoculated with aerobic nitrifying sludge were investigated, the membrane bioreactor (MBR) and anaerobic baffled reactor (ABR), respectively. The result showed that both reactors successfully started up ANAMMOX process. The start-up period of the MBR (90 d) was 20% shorter than the ABR (111 d). During the stable operation, the average nitrogen (NH₄⁺-N+NO₂^--N) removal capacity of 0.098 kg·(m³·d)^-1 in the MBR was also higher than that of 0.089 kg·(m³·d)^-1 in the ABR. In addition, the differences of sludge morphology were obvious in the two reactors; flocculent sludge was developed in the MBR while ANAMMOX granular sludge was mainly formed in the first compartment of the ABR. Moreover, the quantitative relationship analysis between NH₄⁺-N, NO₂^--N and NO₃^--N showed that the MBR system contained more kinds of bacteria with nitrogen removal function, compared to the ABR, and it was therefore more conducive to the removal of nitrogen. MBR exhibited a more excellent performance for ANAMMOX start-up.

[Characterization of pure and doped amorphous WO3 films by Raman spectroscopy]

Pure, TiO2-doped and TiO2/Ag-doped WO3 films were prepared by evaporation and electron beam evaporating. Raman spectroscopy and chronoamperometry were used to characterize the electrochromic properties of the samples. The correlation between the relative intensity of the Raman peaks, corresponding to the Raman sharp peak of the crystalline phase at 810 cm(-1) is negative, that is to say the higher the relative intensity of the Raman peaks, the smaller the coloration efficiency.

[Effect of aminoguanidine on spinal cord edema of acute spinal cord injury in rats]

OBJECTIVE

Aminoguanidine (AG) can reduce brain edema and increase the recovery of neuron functions in surgical brain injury and stroke. To investigate the effect of AG on spinal cord injury (SCI) in rats and its mechanism.

METHODS

A total of 150 adult male Sprague Dawley rats (weighing, 230-255 g) were divided into control group (group A, 25 rats without treatment), the sham-operated group (group B, 25 rats undergoing laminectomy), SCI group (group C, 25 SCI rats with injection of 5% DMSO), SCI + AG groups (groups D, E, and F, 25 SCI rats and AG injection of 75, 150, and 300 mg/kg, respectively). The optimal dosage of AG was screened by dry-wet weight method with the percentage of water content at 0, 12, 24, and 48 hours after injury. The blood-spinal cord barriar permeability was further detected by Evans blue (EB) method, aquaporins 4 (AQP4) mRNA expression by RT-PCR, AQP4 protein expression by immunohistochemistry and Western blot.

RESULTS

AG injection at dosage of 150 mg/kg can significantly reduce edema of spinal cords at 12, 24, and 48 hours after SCI (P < 0.05), so 150 mg/kg was the optimal dosage. The EB content in group E was significantly lower than that in group C at 12, 24, and 48 hours after SCI, and the permeability of blood-spinal cord barrier was significantly decreased compared with group C (P < 0.05). The AQP4 mRNA expressions in groups B and E were significantly lower than that in group C at 12, 24, and 48 hours after SCI (P < 0.05). AQP4 protein expressions in groups B and E were significantly lower than that in group C at 24 and 48 hours after SCI (P < 0.05) by Western blot. Immunohistochemical staining revealed that AQP4 protein expression in group C was significantly higher than that in groups B and E (P < 0.05) at 48 hours after SCI, but no significant difference was found between group B and group E (P > 0.05).

CONCLUSION

AG injection at dosage of 150 mg/kg can induce spinal cord edema and injury in rats, which could be correlated with the down-regulation of AQP4 expression.

Clinical observation of gastric bypass in treatment of type 2 diabetes

BACKGROUND

Roux-en-Y gastric bypass (GBP) is the main surgical procedure used in type 2 diabetes. The objective of this study was to evaluate the different types of GBP in treatment of type 2 diabetes.

METHODS

Patients with type 2 diabetes were randomly divided into two groups: those who underwent gastrojejunal loop anastomosis bypass and those who underwent gastrojejunal Roux-en-Y bypass. Blood glucose alterations, operation time, and operation complications were observed.

RESULTS

Gastrojejunal loop anastomosis bypass and gastrojejunal Roux-en-Y bypass were both effective in the treatment of selected patients with type 2 diabetes. Compared with gastrojejunal Roux-en-Y bypass, gastrojejunal loop anastomosis bypass had the advantages of easier implementation, shorter operation time, and fewer operation complications.

CONCLUSIONS

Gastrojejunal loop anastomosis is effective in treatment of type 2 diabetes. It is safe, easy to implement, and worthy of clinical popularization.

[Effects of bone marrow mesenchymal stem cells transplantation on expression of vascular endothelial growth factor gene and angiogenesis after spinal cord injury in rats]

OBJECTIVE

To investigate the effect of bone marrow mesenchymal stem cells (BMSCs) transplantation on the motor function recovery, the expression of vascular endothelial growth factor (VEGF) gene, and angiogenesis after spinal cord injury (SCI) in rats, and to explore the treatment mechanism of BMSCs in SCI.

METHODS

BMSCs were isolated and cultured from the marrow of 5 Wistar rats (4 weeks old) and the 3rd-4th passage cells were prepared for the experiment. A total of 87 adult female Wistar rats (weighing 220-250 g) were randomly divided into 3 groups: sham-operated group (group A, n=21), DMEM group (group B, n=33), BMSCs group (group C, n=33). A laminectomy was only performed at T8-10 levels in group A. The SCI models were established by modified Nystrom's compression method in groups B and C, and BMSCs and DMEM were injected in groups B and C respectively at 30 minutes after SCI. Basso-Beattie-Bresnahan (BBB) score was used for the motor function recovery at 3, 7, 14, and 28 days, RT-PCR for the VEGF mRNA at 1, 3, and 5 days, and immunohistochemical staining for angiogenesis at 3, 7, 14, and 28 days.

RESULTS

In groups B and C, the hindlimb locomotor function was improved at different degrees with time, showing significant difference in BBB score between groups B, C and group A (P < 0.05). At 28 days, the BBB score in group C was significantly higher than that in group B (P < 0.05) and there was no significant difference between groups B and C (P > 0.05) at 3, 7, and 14 days after transplantation. The numbers of microvessels in the ventral horns of gray matter around SCI in groups B and C were significantly lower than that in group C (P < 0.05) at 3 days, but there was no significant difference at 7, 14, and 28 days after transplantation (P > 0.05). There was no significant difference in the number of microvessels between group C and group B (P > 0.05) at 3 and 7 days, but the number of microvessels in group C was significantly higher than that in group B (P < 0.05) at 14 and 28 days after transplantation. However, there was no significant difference in the number of microvessels in the white matter around SCI in 3 groups at different time points after transplantation (P > 0.05). The RT-PCR results showed that VEGF mRNA expressed at a low level in group A. Compared with group A, the expression level of VEGF mRNA in groups B and C increased at 1 day and reached the peak at 3 days, then decreased at 5 days after transplantation; and the expression of VEGF mRNA was significantly higher in groups B and C than in group A (P < 0.05), and in group C than in group B (P < 0.05) at 1, 3, and 5 days.

CONCLUSION

BMSCs may promote the motor function recovery by up-regulating VEGF mRNA expression and increasing angiogenesis in the spinal cord after SCI in rats.

[Expression and clinical significance of TLR9 in ovarian cancer]

OBJECTIVE

To detect the expression of Toll-like receptor 9 (TLR9) in ovarian cancer, and to explore their clinical significance.

METHODS

Western blot method and immunohistochemical staining were used to examine the expression of TLR9 in the ovarian cancer, paracancerous tissues and normal ovarian tissues, obtained during operation from 30 ovarian carcinoma patients and 30 normal non-tumor patients. The relationships of TLR9 with pathological grade, clinical stage, and metastasis of ovarian cancer were statistically analyzed.

RESULTS

The percentage of positive cells expressing TLR9 protein in human ovarian cancer tissues, paracancerous tissues and normal ovarian tissues were 80.0%, 36.7% and 20.0%, respectively. The protein expression level of TLR9 was gradually descending (P < 0.01). The highly expressed TLR9 significantly correlated with the degree of tumor differentiation, an advanced FIGO stage and lymph node metastasis. The Western blot results showed that TLR9 protein expression in ovarian cancer, paracancerous tissues and normal ovarian tissues were 0.803 ± 0.072, 0.411 ± 0.087 and 0.113 ± 0.065, respectively. The expression of TLR9 in ovarian cancer was significantly higher than that in normal tissue and paracancerous tissues (P < 0.01).

CONCLUSIONS

TLR9 has a higher expression in ovarian cancer tissues. TLR9 expression has a close relationship with pathological grades of ovarian cancer, suggesting that TLR9 plays an important role in the development and progression of ovarian cancer through immunologic mechanisms.

[Neural stem cells transplantation promote the expressions of brain derived neurotrophic factor after the spinal cord injury of rats]

OBJECTIVE

To observe the effects of neural stem cells (NSCs) transplantation on the brain derived neurotrophic factor (BDNF) after the spinal cord injury (SCI) of rats, and to investigate the mechanism of repairing the SCI by NSCs transplantation.

METHODS

Neural stem cells were cultured from the hippocampus of rats' embryo and identified by immunocytochemistry. Seven days after the operation of SCI, the NSCs were transplanted into the injured site. Sixty adult Wistar rats were randomly divided into three groups: SCI cured with NSCs transplantation (group A), SCI received DMEM solution (group B), control group (group C). Then the expression of BDNF of the lesion and neighbor areas were examined by reverse transcsription polymerase chain reaction (RT-PCR) and immunohistochemistry, so as to investigated the mechanism of repairing the SCI after NSCS transplantation.

RESULTS

According the RT-PCR results analysis, the expression of BDNF mRNA of group A enhanced higher than that of group B on the 1st, 3rd, 5th day after transplantation of NSCs. According the immunohistochemistry results analysis, the expression of BDNF mRNA of group A enhanced higher than that of group B on the 7th, 14th, 28th day similarly.

CONCLUSION

The transplantation of NSCs can change the tiny-entironment by upregulating the expression of BDNF. It maybe one of the mechanism of repairing the SCI by NSCs transplantation.

[Study on the pathological uterine tissues with a fiber Raman spectrometry]

The Raman spectrum can reflect the differences in chemical components and molecular structures of tissues and cells, and significant progress has been made in the research on structures, functions and diseases of cells and tissues with Raman spectroscopy. A fiber Raman spectrometer was used to measure the Raman spectra of some uterine malignant, benign, and normal tissues, such as uterine myometrium tissue, uterine myoma tissue, normal endometrium tissue, malignant endometrium tissue and adenomyosis tissue. After having compared the Raman spectrum of pathological tissues with that of the corresponding normal tissues, we observed that the peak referring to Methionine upsilon(C--S) (Met upsilon(C--S)) splits into two peaks in the uterine myoma tissues caused by the vibrations of tryptophan (Trp) and cartotene, which are not present in the normal tissues. There is a peak at 1447 cm(-1) in the endometrium tissues corresponding to CH2--CH3 def, which is one of the characteristic peaks of cancerous tissues. For the adenomyosis tissues, a peak caused by upsilon(C--C) skeletal-alpha helix is obviously weaker than that in normal tissue, and the peak induced by delta(C--O) shifts from 1160 cm(-1) in normal tissues to 1173 cm(-1) in the adenomyosis tissues. Thus, it was demonstrated that the technology of Raman spectroscopy is available for distinguishing different pathological uterine tissues at molecular level. This study is not only helpful on early diagnosis of uterine diseases, but also very crucial for the basic research on uterine diseases. And the Raman spectroscopy technology based on optic-fibers has a potential to evolve into a highly sensitive technology for diagnosis.

[Effects of cryopreserved neural stem cells transplantation on rat axonal regeneration after spinal cord injury]

OBJECTIVE

To observe the effects of cryopreserved (-70 degrees C) neural stem cells (NSCs) transplantation on the axon regeneration after the spinal cord injury (SCI) of rats.

METHODS

Neural stem cells were cultured from the hippocampus of the rat's embryo and identified by immunocytochemistry of nestin, then NSCs in logarithmic phage were cryopreserved (-70 degrees C) for 2 weeks. Seven days after the operation of SCI, the NSCs in were transplanted into the injured site immediately. Thirty six adult Wistar rats were randomly divided into three groups: spinal cord injury treated with transplantation of NSCs to the injured site (Group A), spinal cord injury received DMEM solution (Group B), control group (Group C). Then NSCs labeled with Brdu were detected by immunohistochemisty, and the reconstruction of spinal cord were detected by horseradish peroxidase (HRP) staining.

RESULTS

NSCs can be detected in the spinal cord after transplantation. The number of HRP positive cells of Group A was higher than that of Group B.

CONCLUSION

The transplantation of cryopreserved NSCs can survived in the injured site and promote the reconstruction. It may be a progress in the repairing of the SCI by cells transplantation.

[Differentiation of human telomerase reverse transcriptase immortalized human marrow mesenchymal stem cell into chondrocyte]

OBJECTIVE

To establish an immortalized marrow mesenchymal stem cell line to facilitate advances in cartilage engineering research.

METHODS

Human telomerase reverse transcriptase (hTERT) cDNA was transferred into primary human marrow mesenchymal stem cells (hMSC) by retroviral vector pLEGFP-C1-hTERT. Subsequently G418 resistant cell clone was screened and expanded for further studies. hMSC biomarkers and hTERT expression were confirmed by examination. Transfected hMSC was induced to differentiate into chondrocyte using TGF-P1 and dexamethasone.

RESULTS

Up-regulated hTERT expression was detected in transfected hMSC. hMSC-hTERT cells could be induced to differentiate into chondrocyte. Higher telomerase activity in transfected cells was maintained for 50 population doublings so far. Collagen II could be detected in induced transfected hMSC by immunocytochemical and hybridization in situ.

CONCLUSIONS

Ectopic expression of hTERT can effectively immortalize hMSC in vitro. Immortalized hMSC can be induced to differentiate into chondrocyte under certain condition. It may be an ideal target of further studies in cartilage engineering.

Influence of ethanol-diesel blended fuels on diesel exhaust emissions and mutagenic and genotoxic activities of particulate extracts

This study was aimed at evaluating the influence of ethanol addition on diesel exhaust emissions and the toxicity of particulate extracts. The experiments were conducted on a heavy-duty diesel engine and five fuels were used, namely: E0 (base diesel fuel), E5 (5%), E10 (10%), E15 (15%) and E20 (20%), respectively. The regulated emissions (THC, CO, NOx, PM) and polycyclic aromatic hydrocarbon (PAH) emissions were measured, and Ames test and Comet assay, respectively, were used to investigate the mutagenicity and genotoxicity of particulate extracts. From the point of exhaust emissions, the introduction of ethanol to diesel fuel could result in higher brake specific THC (BSTHC) and CO (BSCO) emissions and lower smoke emissions, while the effects on the brake specific NOx (BSNOx) and particulate matters (BSPM) were not obvious. The PAH emissions showed an increasing trend with a growth of ethanol content in the ethanol-diesel blends. As to the biotoxicity, E20 always had the highest brake specific revertants (BSR) in both TA98 and TA100 with or without metabolizing enzymes (S9), while the lowest BSR were found in E5 except that of TA98-S9. DNA damage data showed a lower genotoxic potency of E10 and E15 as a whole.

[Application of RF-II pedicle screw system in lumbar spondylolisthesis]

Thirty-eight patients with isthmic(31 cases), degenerative(6 cases), and post-traumatic(1 case) spondylolisthesis were treated with RF-II pedicle screw system. Eighteen patients were classified as Degree I lesion, 14 as Degree II lesion, and 6 as Degree III lesion. Postoperatively, 34 cases(90%) obtained an anatomical improvement obviously. The percentage of the patients who got excellent and good recovery was above 90%. We conclude that RF-II pedicle screw fixation system has the strongest three-dimensional rigidity and, attains complete and satisfactory decompression. The entire intervertebral disk in the level of the lesion is suggested to be removed. The system is ingeniously and originally designed, and is easy to obtain a simple and an effective reduction of the spondylolisthesis. Additionally, the application of the system can obtain a good interbody fusion by three steps: broadening the interbody space; stuffing the space with broken bones; and compressing the involved vertebral body. The authors considered that the RF-II screw system is one of the most ideal internal fixations for the treatment of lumbar spondylolisthesis.

[Tumor of the skull-report on 119 patients]

OBJECTIVE

To study the pathologic type, clinical manifestations and treatment of skull neoplasms.

METHODS

A series of 119 patients with skull neoplasm were analyzed retrospectively with respect of clinical manifestations, radiologic features, treatment and prognosis.

RESULTS

122 operations were done with 3 patients being operated twice. Complete resection was done 75 times, subtotal resection 24 times, partial resection 22 times and biopsy only once. Gross type: exophytic 43(36.1%), endophytic 27(22.7%) and mixed type 49 (41.2%). Among the 85 patients followed, 78.6% have recovered and are living well, 16.6% of patients are self-caring, 2 need others' help and 2 have died.

CONCLUSION

Most skull neoplasms require neurosurgical intervention. Surgical excision is able to confirm the diagnosis, slow down the progression of neurologic dysfunction, prolong the patients' lives and improve the cosmetic results.

Clinical significance of examining IL-2R in peripheral blood lymphocytes of patients with gastric cancer

OBJECTIVE

To understand the clinical significance of membrane receptors of interleukin-2 (CD25) in peripheral blood lymphocytes (PBL) of patients with gastric cancer.

METHODS

CD25 percentages in PBL from 110 patients with gastric cancer and 100 normal individuals were examined by flow cytometry. Results were analyzed clinically and pathologically.

RESULTS

Mean CD25% in PBL from normal individuals and patients with gastric cancer were 17.24 +/- 5.33 and 22.47 +/- 6.82, respectively, and the difference was significant (P < 0.01). Abnormally elevated CD25% in PBL from patients with gastric cancer were correlated with tumor site, macropathology type, tumor size, differentiation degree and clinical stage.

CONCLUSION

Measuring CD25% in PBL from gastric cancer patients before surgery may provide a reference for diagnosis, immune treatment and judging prognosis.

[The effects of ethanol on neuromuscular junctions of adult toad]

OBJECTIVE

To investigate the effects of ethanol on the transmission at the neuromuscular junctions(NMJ) and the possible mechanism thereby.

METHODS

The effects of ethanol on the endplate potential (EPP) and miniature endplate potential(MEPP) of sciatic nerve-sartorious muscle preparations of 20 adult toads (Bufo bufo gargarizans) were studied in vitro by means of intracellular microelectrode recording.

RESULTS

Ethanol could cause the changes in EPP amplitude so as to influence the transmission at NMJ, and the effects apparently depended on the concentration of the ethanol. A proper concentration of ethanol could produce a significant increase in EPP amplitude and therefore facilitate the transmission at the NMJ. A proper concentration of ethanol also could produce a significant increase in MEPP frequency but had no influence on MEPP amplitude.

CONCLUSION

Ethanol can increase the quantal number of transmitters released from presynaptic part. That may be one of the reasons why ethanol can facilitate the transmission at the NMJ.

A study of Hodgkin/Reed-Sternberg cells using single cell polymerase chain reaction

OBJECTIVE

To investigate the characteristics of Hodgkin/Reed-Stemberg (H/R-S) cells found in patients with various types of Hodgkin's disease (HD).

METHODS

H/R-S cells were micropicked from frozen sections of tissues affected by HD. The DNA from these cells was amplified by polymerase chain reaction (PCR) using immunoglobulin heavy chain gene FR III a/JH primers and light chain gene family-specific primers.

RESULTS

A total of 52/135 (35.8%) isolated cells showed the specific products in the reactions. IgH and V kappa 4 rearrangements were repeatedly found in many cells from a lymphocyte predominance type sample; repeated V kappa 4 and individual IgH/V kappa 2,4 rearrangements and individual IgH, V lambda 3/ V kappa 4 rearrangements were found in two different cases of the nodular sclerosis type; repeated IgH/ V lambda 3 and individual V lambda 2,4 rearrangements, repeated V kappa 2,4 rearrangements, repeated V kappa 4 and individual IgH/ V kappa 3 rearrangements, repeated IgH and individual V kappa 3/ V lambda 4 rearrangements were detected in 3 cases of the mixed cellularity type. Repeated and individual IgH rearrangements were found in other 2 cases.

CONCLUSION

The H/R-S cells isolated from the lymphocyte predominance subtypes of HD have IgH and V lambda 4 gene rearrangements. This suggests that the lymphocyte predominance type is a proliferation of neoplastic B cells. The cells isolated from the mixed cellularity and nodular sclerosis types derive from B lineage cells at various stages of differentiation because of the presence of their IgH, kappa and/or lambda gene rearrangements. To our knowledge, this is the first time that the lambda gene rearrangement was detected in H/R-S cells.

[Multiple tumor suppressor 1/p16 gene alterations in human esophageal squamous-cell carcinoma: clinical significance and regional difference]

OBJECTIVE

To further understand multiple tumor suppressor 1/p16 (mts1/p16) gene alterations in squamous-cell esophageal carcinoma (EC) in relation to its biologic behavior and regional difference.

METHODS

Samples of human EC from 92 patients residing in Zhejiang province and in Linxian, Henan province were analyzed for the expression, mutation and deletion of the multiple tumor suppressor gene (mts1/p16) by immunohistochemical staining, polymerase chain reaction and single strand conformation polymorphism.

RESULTS

mts1/p16 expression at protein level was demonstrated in 44 cases (47.8%). Gene deletion was detected in 22 cases (23.9%) and point mutation in 5 cases (5.4%). Expression of mst1/p16 showed significant correlation with pathologic staging, lymph node status and survival. However, deletion of mst1/p16 did not show correlation with the clinico-pathologic parameters. EC patients in stage T2 from Linxian had significantly lower rate of mst1/p16 protein expression compared to those from Zhejiang province at the same time period. Moreover, there was close association between gene alterations (mutation + deletion) and frequency of lymph node metastasis in Zhejiang EC patients. No such association was observed in EC patients from Linxian.

CONCLUSION

msts1/p16 gene alteration is a common genetic event in the carcinogenesis and progression of human esophageal cancer. EC patients from two different regions present differential alterations in mst1/p16 gene.

[Effect of ATP on malignant phenotype of a human gastric cancer cell line]

OBJECTIVE

To study the effect of ATP on proliferation and differentiation of a human gastric cancer cell line.

METHODS

M17, a subclone of human gastric cancer cell line MGC-803, was treated in vitro with ATP(0.23 mg/ml). After 48 hr, the following parameters were examined. (1) Proliferation of cells by daily cell counting. (2) Microvilli of the cells were observed by scanning EM. (3) Gap junction intercellular communication was examined by mechanical scraping and Lucifer dye transfer. (4) Microfilament of the cytoskeleton was studied with fluorescin-labeled phalloidin. (5) Vinculin adhesion plague was stained immunocytochemically with monoclonal antibodies.

RESULTS

ATP significantly inhibited the in vitro growth of M17 cells. The ATP-treated M17 cells showed disappearance of microvilli on the cell surface, increased gap junction intercellular communication, improved organization of microfilament bundles and reappearance of vinculin adhesion plagues.

CONCLUSION

ATP not only inhibits proliferation but also induces differentiation of a human gastric cancer cell line with reversion from malignant toward normal phenotype. The parameters examined could serve as useful biomarkers of human gastric cancer.

Hodgkin's disease: immunoglobulin heavy and light chain gene rearrangements revealed in single Hodgkin/Reed-Sternberg cells

AIM

To corroborate and investigate the nature of Hodgkin/Reed-Sternberg cells (H/R-S) of various subtypes of Hodgkin's disease.

METHOD

Single H/R-S cells were micro-picked from frozen sections of tissues affected by Hodgkin's disease. The DNA from these cells was amplified by the polymerase chain reaction (PCR) with immunoglobulin heavy chain (IgH) gene FRIIIa/JH primers and light chain gene family specific primers.

RESULTS

Fifty two of 135 isolated cells gave specific reaction products (36%). IgH and V kappa 4 gene rearrangements were found repeatedly in many H/R-S cells from one case of lymphocyte predominant Hodgkin's disease. Repeated V kappa 4 and individual IgH/V kappa 4,2 rearrangements were seen in one case, and individual IgH and V lambda 3/V kappa 4 rearrangements were seen in another case of nodular sclerosis-type Hodgkin's disease. Repeated IgH/V lambda 3 and individual V lambda 2,4 rearrangements, repeated V kappa 4 and individual IgH/V kappa 3 rearrangements, and repeated IgH and individual V kappa 3/V kappa 4 rearrangement were detected, respectively, in three cases of mixed cellularity-type Hodgkin's disease. Repeated and individual IgH rearrangements were found in another two cases of mixed cellularity-type Hodgkin's disease.

CONCLUSION

The H/R-S cells isolated from lymphocyte predominant Hodgkin's disease had IgH and V kappa 4 gene rearrangements, which supports the conclusion that this disease results from a proliferation of neoplastic B cells. The IgH and kappa and/or lambda gene rearrangements seen in H/R-S cells isolated from classic Hodgkin's disease (mixed cellularity-type and nodular sclerosis-type) support the theory that these cells derive from B lineage cells at various stages of differentiation. To our knowledge, this is first time that lambda gene rearrangements have been detected in H/R-S cells.

[The effects of Tripterygium wilfordii polyglycosidium on neuromuscular junctions of adult toad]

The effects of tripterygium wilfordii polyglycosidium (TWP) on the transmission at the neuromuscular junctions (NMJ) of sciatic nerve-sartorius muscle preparations of 20 adult toads (Bufo bufo gargarizans) in vitro were studied by means of intracellular microelectrode recording of endplate potentials (EPP). The results revealed that TWP could cause changes of EPP amplitude so as to influence the transmission at NMJ, and the effects apparently depended on the concentration of the drug. A proper concentration of TWP could produce a significant increase in EPP amplitude and therefore facilitate the transmission at the NMJ.

[Effects of estrone on transmission at neuromuscular junction of the toad]

The effects of estrone on neuromuscular transmission were studied intracellularly at the muscle fiber endplate in isolated sciatic nerve-sartorius muscle preparations of the toad (Bufo bufo gargarizans) in vitro. The results showed that estrone (10(-4) mol/L), added to bath medium, caused an increase in amplitudes of endplate potentials (EPP) both in 10 micrograms tubocurarine treated and 10 mmol/L MgCl2 treated preparations, but the increase was more prominent in the former, and that estrone, 30 min after being added to bath medium, caused clear increase both in frequency and amplitude of miniature endplate potentials (MEPP), but the wave form of MEPP remained unchanged and the resting membrane potentials were also unchanged. These results suggest that estrone can increase neuromuscular transmission, which seems to involve primarily the presynaptic mechanism.

[A preliminary study on the hormonal causes of seasonal change in miniature endplate potentials at the neuromuscular junctions of the toad]

The hormonal causes of seasonal change in amplitudes of miniature endplate potentials (MEPP) in the adult toad (Bufo bufo gargarizans) were studied with intracellular recordings of MEPP at the neuromuscular junction of sartorius muscle fiber in vitro by adding L-thyroxine sodium and estrone to the bath medium during spring and autumn respectively. The results showed that L-thyroxine sodium (50 mumol/ L) could not change the amplitude of MEPP, regardless of spring or autumn, but estrone (100 mumol/L) could cause a clear increase in MEPP amplitude in both seasons. From these results it was presumed that thyroxine might be less related to the seasonal changes in MEPP amplitude whereas the seasonal fluctuations of gonadal hormones in the body might play a role.

[Seasonal variation and circannual rhythm of miniature end-plate potentials recorded from the neuromuscular junctions of the adult toad (Bufo bufo gargarizans)]

The seasonal variations and circannual rhythm of miniature end-plate potentials (MEPP) recorded from the sartorius neuromuscular junctions (NMJ) of 66 female and 62 male adult toads (Bufo bufo gargarizans) were studied with intracellular microelectrode recording techniques of electrophysiology. The results revealed that the mean amplitude of MEPP in each month of a year showed clear seasonal variation with a nadir in September and October and a zenith in March and April. This seasonal variation in MEPP amplitude was proved to be a circannual rhythm by single cosinor analysis and zero amplitude test, and the three parameters of the rhythm, i.e. mesor, amplitude and acrophase were 0.29 +/- 0.05 mV, 0.25 mV and -97.17 degrees in female toad and 0.19 +/- 0.02 mV, 0.16 mV and -92.01 degrees in male toad, respectively; the circannual rhythm in female toad was more distinct than that in male. Neither seasonal variation nor circannual rhythm was statistically significant in the changes of frequency of MEPP, regardless of toad sexuality.

[The changes of glucocorticoid receptor and beta-adrenoreceptor of lung tissues in SD rat asthma models and the effects of antiasthmatics on them]

OBJECTIVE

To observe the changes of glucocorticoid receptor (GR) and beta-adrenoreceptor (beta-AR) of lung tissue and the effects of oral procaterol, salbutamol and intraperitoneal (i.p.) or inhaled (i.h.) dexamethasone (Dex).

METHOD

The GR or beta-AR were determined by using 3H-dexamethasone and 3H-Dihydroalprenolol as ligand respectively, in groups of rat asthma models at 1, 3, 7, 14th day and groups received antiasthmatics on the 7th day after daily consecutive challenges.

RESULTS

The GR Bmax of asthma groups increased significantly after the first challenge, but decreased since the third day to a lower level than that of healthy control. The KD also decreased significantly since the third day. The beta-AR Bmax of asthma group gradually decreased to a significant low level on the 14th day. The Dex i.p. group had the lowest GR Bmax and the Dex i.h. group had the highest beta-AR Bmax among the treated. In the procaterol and salbutamol group, there had no decrease of GR Bmax compared with that of controls.

CONCLUSIONS

The GR and beta-AR levels of lung tissues changed after daily challenges. The GC played a down-regulation role on GR and an up-regulation role on beta-AR in lung tissues. The Dex i.h. had more advantages than Dex i.p. in terms of GR and beta-AR regulations.

Intraoperative thrombolytic treatment of microarterial occlusion by selective rt-PA infusion

The development of microvascular thrombosis during replantation surgery or free-flap transfer is generally best treated by identification of the problem, vascular revision, and reanastomosis. It is not unique, however, that surgical measures alone are insufficient or undesirable. Pharmacologic adjuncts are widely used for the prevention and sometimes treatment of microvascular thrombosis in surgical practice, but the benefit of thrombolytic agents, effective in dissolving an already established thrombus, is usually considered counterlevered by the fear of uncontrollable bleeding. However, selective infusion of the drug reduces the risk for systemic complications considerably and may therefore be considered in peripheral microvascular reconstruction. The technique was used successfully in a case of digital revascularization, where an arterial thrombosis was dissolved with the use of recombinant tissue plasminogen activator (rt-PA).