BACKGROUND: With the continuous development of materials science, magnesium alloy vascular stent materials have become a hot research. Because of the mechanical properties and biocompatibility of commercial magnesium alloy, it is difficult to meet the requirements of vascular stents. Therefore, effective measures to improve the sten's surface properties and comprehensive performance become the focus of research.OBJECTIVE: To study the histology and surface modification of vascular stents in rapidly solidified Mg-Zn-Y-Nd alloy.Methods: The low-zinc Mg-2Zn-0.2Y alloy with good mechanical properties and corrosion resistance was selected as the basic material, and Nd and Zn elements were added to refine the alloy stents. After the microstructure of the stent was extruded, the surface modification of the stent was completed and the comprehensive properties of the alloy were improved. The new magnesium alloy for the stent was obtained and the stent surface was modified. The metallographic microstructure, scanning electron microscopy and radiological analysis were used to study the microstructure and mechanical properties of the prepared stents. The mechanical properties of the stents were investigated by hardness and tensile tests.RESULTS AND CONCLUSION: (1) Metallographic microstructure results showed that: when Y elements were not added, the second phase of the magnesium alloy was rod-shaped, and there were a few granules embedded in the matrix. After addition of 0.5% Y elements, in the second phase of the magnesium alloy stent, the shafts were significantly reduced in number, and granules were increased in number and evenly distributed in the body. After the addition of 1% Y,the second phase number increased, a large number of dendrites were visible in the grains, and discontinuous rods existed in the second phase. After the addition of 1.5% Y, the second phase was rod-shaped, with mixture of large and local dendrites in the alloy. (2) X-ray diffraction test results: Mn-Zn-0.5Nd alloy and Mn-Zn-1.0Nd alloy contained the same phases (Mg4Zn7 and (Nd, Y) 2Zn17 phase). When the concentration of Nd increased to 1%, the new MgZn2 phase appeared in the alloy. (3) SEM & EDS test results of modified magnesium alloy showed that after magnesium alloy modification, the second phase contained Zn, Nd and Y elements, and their contents were very close. EDS analysis showed that after the addition of Zr elements, the level of Zn elements in the lamellar second phase decreased significantly, and the level of Nd and Y elements increased, indicating a more stable performance. (4) Micro-hardness test results showed that with the increasing of the content of magnesium alloy, the alloy microhardness increased. (5)Tensile test results showed that the tensile strength and yield strength of the Mg-Zn-Y-0.5Nd-Zr stent were significantly higher than those of Mg-Zn-Y-0.5Nd, Mg-Zn-Y-1.0Nd,Mg-Zn-Y-1.0Nd-Zr stents (P < 0.05); and the elongation at break of Mg-Zn-Y-0.5Nd-Zr and Mg-Zn-Y-1.0Nd-Zr stents was significantly higher than that of Mg-Zn-Y-1.0Nd and Mg-Zn-Y-0.5Nd stents (P < 0.05). To conclude, with Mg-2Zn-0.2Y as core materials, the material modification could be completed by the addition of Nd and Zn elements, and the surface modification could be implemented by extruding and refining the stent microstructure. The modified material has excellent properties.

Objective To discuss the surgical method and efficacy of adult Dandy-Walker syndrome ( DWS) through retrospective anal-ysis and literature review .Methods There were 3 cases of adult DWS in our hospital from August 2010 to August 2011.One case of them was given posterior cranial fossa cyst peritoneal shunt , and the surgery adopted ordinary high voltage shunt .Case 2 was given left side of the lateral ventricle peritoneal shunt , and the surgery adopted ordinary high voltage shunt .Case 3 was given posterior cranial fossa cyst peritoneal shunt combined with left side of the lateral ventricle peritoneal shunt , and the surgery adopted double-end high voltage shunt .The two ends of the shunt were respectively linked with the diverter valve and abdominal cavity drainage tube through T -branch pipe .Results Among the 3 patients, there was 1 case failed to ease the headache symptoms , and it was relieved one month later .The preoperative symptoms of the oth-er 2 cases disappeared immediately after the surgery .During the 4 years of follow-up,preoperative symptoms of the 3 patients disappeared , and there was no positive signs .Conclusion For adult patients with symptomatic DWS ,shunt surgery can eliminate symptoms ,relieve the tension of the posterior fossa cyst ,achieve good curative effect , and there was no surgical complication .

Objective To investigate the correlation of plasma interleukin ( IL)-17 level and IL-17 receptor (IL-17R) expression in the thymus of patients with myasthenia gravis (MG).Methods The blood samples of 63 patients (38 with glucocorticoid treatment, 25 with thymus removal) who admitted to Henan Provincial People′s Hospital between 2010 and 2014 were collected at three different stages: pre-treatment, 1 week post-treatment and 1 month post-treatment.The blood samples of 42 healthy controls were also collected.Enzyme linked immunosorbent assay was used to evaluate the levels of IL-17 in plasma.Twenty-five thymus tissues from MG patients and another 12 thymus tissues from patients with congenital heart disease who had surgery therapy were also collected.Reverse transcription polymerase chain reaction was used to evaluate the mRNA levels of IL-17R.The possible correlation between the expression of IL-17 and IL-17R with MG was analyzed.Results Before treatment, the levels of IL-17 in the plasma were much higher in all the MG patients ( both ocular and generalized) when compared to the healthy controls ( controls (3.2 ±0.7) pg/ml, MG patients (8.5 ±1.7) pg/ml, t =2.450, P <0.01; generalized type patients (9.7 ±1.4) pg/ml, t =2.532, P <0.01).In the patients with glucocorticoid treatment, IL-17 levels began to reduce after 1 week treatment and a statistically significant difference was found when compared to the pre-treatment samples (pre-treatment (8.3 ±1.2) pg/ml, 1 week after treatment (6.3 ±0.7) pg/ml, t=2.052, P<0.05) and healthy controls (t =1.933, P<0.05).One month after the glucocorticoid treatment, the levels of IL-17 decreased to the normal level (1 month after treatment (3.9 ±0.6) pg/ml, t=2.630, P <0.01, compared to the pre-treatment; t =1.395, P >0.05, compared to the healthy controls).In the surgery therapy cases, the IL-17 levels were also reduced after the thymus removal ( pre-surgery (8.8 ±1.4) pg/ml, 1 week after surgery (5.3 ±0.7) pg/ml, t=1.950, P<0.05;1 month after surgery (3.0 ±0.4) pg/ml, t=2.683, P<0.01).In the thymus tissues of the MG patients, the mRNA levels of IL-17R were much higher than that of the controls ( relative level 2.31 folds, t =2.682, P <0.01).Meanwhile, a positive correlation was found between the plasma IL-17 levels and the relative IL-17R levels in thymus tissues ( r =0.945 4, P <0.01 ).Furthermore, IL-17 was positively correlated with quantitative myasthenia gravis scores (QMGS) either pre-treatment (r =0.798 1, P <0.01) or post-treatment (r=0.906 5, P<0.01).And IL-17R was positively correlated with QMGS pre-treatment (r=0.775 5, P<0.01).Conclusions IL-17 is increased in the plasma of MG patients (both ocular and generalized) , and is decreased upon the glucocorticoid treatment or surgery therapy, suggesting that it can be used as a parameter to determine the therapeutic effects.IL-17R is increased in the thymus tissues of MG patients, suggesting that it can potentially be used as a pathological diagnosis parameter.

Objective To evaluate the clinical value of multi-slice spiral CT (MSCT)in the screening of coronary artery lesions in elderly patients with diabetes mellitus.Methods MSCT and coronary angiography(CAG)were performed in 136 elderly patients(68 patients with diabetes and 68 patients without diabetes).The number of diseased coronary segments and the plaque type (noncalcified,mixed and calcified)for each patient were determined.The characteristics of coronary lesions were compared between patients with and without diabetes.The sensitivity and specificity of MSCT were evaluated.Results More noncalcified and calcified plaques and few ermixed plaques were observed in patients with diabetes,compared with patients without diabetes(noncalcified plagues:10 cases or 14.7％ vs.4 cases or 5.9％;calcified plagues:47 cases or 69.1％ vs.39 cases or 57.4％)(P＜ 0.05).In addition,diabetic patients showed a significantly higher frequency of multivessel disease(P＜0.05).Furthermore,MSCT was able to clearly show stenosis and plaque type in the trunk and branches of the coronary artery,with a sensitivity of 91.0％,a specificity of 95.0％,a positive predictive value of 93％ and a negative predictive value of 96.0％.Conclusions Diabetes is associated with a higher risk of coronary artery disease.MSCT can effectively detect the characteristics of coronary artery disease in diabetic patients and is an effective,noninvasive,and safe screening method.

Objective:To evaluate the renal injury of ultrasound-guided percutaneous fascia dilatation with one-step and multi-step percutaneous renal dilatation on renal injury in pigs.Methods:20 experimental pigs were randomly divided into 16F group and 24F group, with 10 pigs in each group. Under the guidance of ultrasound, the left and right kidneys of each experimental pig in group 16F were expanded by percutaneous renal multi-step expansion and one-step expansion (multi-step dilation subgroup and one-step dilation subgroup respectively) with 16F expander, and the same operation was performed with 24F expander in 24F group. After the operation, the left and right kidneys were left with fistula tubes for 1 week. The duration of hematuria in the renal fistula tubes was observed and compared. One month later, the experimental pigs were killed and the kidneys were removed. The histopathology of each group was observed under the naked eye and microscope. The scar tissue around the nephrostomy channel was removed, and hematoxylin-eosin (HE) and Masson staining were performed respectively. The scar volume was measured by digital image analysis technology, and the percentage of the scar volume in the renal cortex volume was calculated.Results:There was no significant difference in gross hematuria duration between one-step dilation subgroup [(4.60±1.26)d] versus multi-step dilation subgroup [(4.70±1.17)d] of 16F group ( P>0.05); There was no significant difference in gross hematuria duration between one-step dilation subgroup [(5.40±1.25)d] versus multi-step dilation subgroup [(5.50±1.08)d] of the 24F group ( P>0.05). There was no significant difference in the gross and histological observation of pig kidney specimens in 16F group and 24F group. There was no significant difference in the scar volume of the fistula channel [(0.35±0.04)cm 3, (0.36±0.03)cm 3] and its percentage in the whole renal cortical volume [(0.41±0.05)%, (0.41±0.06)%] between one-step dilation subgroup versus multi-step dilation subgroup of 16F group (all P>0.05); there was no significant difference in the scar volume of the fistula channel [(0.48±0.02)cm 3, (0.49±0.04)cm 3] and its percentage in the whole renal cortical volume [(0.52±0.04)%, (0.53±0.07)%] between one-step dilation subgroup versus multi-step dilation subgroup of 24F group (all P>0.05). The scar volume and its percentage in the whole renal cortical volume of the one-step dilation subgroup and the multi-step dilation subgroup in the 24F group were higher than that of the 16F group, with statistically significant difference (all P<0.05). Conclusions:Both one-step and multi-step percutaneous renal dilatation have less damage to renal parenchyma. The multi-step dilatation has no obvious advantage over one-step dilatation in reducing renal parenchyma injury.