BACKGROUND: Streptococcus mutans (S. mutans) is generally considered to be the principal aetiological agent for dental caries, thrS gene may relate to the virulence of S. mutans involved in the adherence, acidogenicity and acidodurance.OBJECTIVE: To investigate the conservation status of the thrS gene of S. mutans and to construct the homologous recombinant plasmid.METHODS: Southern Blot was used to analyze the distdbuUon of thrS gene in S. mutans. The upstream and downstream sequences of thrS gene were cloned respectively into multiple cloning sites of suicide plasmid pFW5 to construct the recombinant plasmid,RESULTS AND CONCLUSION: The thrS gene was conserved in 6 strains of S. mutans in this test. By PCR analysis and enzyme digesting, it was confirmed that S. mutans thrS gene homologous recombinant plasmid was successfully constructed,which can be used in future research of construction of thrS -negative mutans of S. mutans strain UA159.

Objective To evaluate and compare the safety and advantage of different kinds of electrode system (monopolar and plasmakinetic techniques) in transcervical resection of myoma (TCRM). Methods A total of 60 patients undergoing TCRM were enrolled. Serum sodium (Na~+), chlorine (Cl~-), potassium (K+) and glucose (Glu) were measured before and after the operation. Meanwhile, the operation time, absorption volume and bleeding volume were also recorded after the operation. Results ① There were significant decreases in Na~+, Cl~-, K~+ and Glu concentrations in the monopolar group (P<0.05), but Glu increased significantly (P<0.05). Na~+, Cl~-, K~+ and Glu concentrations in plasmakinetic group, however, did not change significantly before and after the operation (P>0.05). ② After the operation, there were significant differences between the two groups in Na~+, Cl~- and Glu changes (P<0.05). The absorption volume and volume of bleeding during the operation were increased in monopolar group compared with those in plasmakinetic group (P<0.05). ③ In monopolar group, Na~+, Cl~- and Glu concentrations, the operation time, absorption volume and volume of bleeding were significantly higher in patients with type Ⅱ myoma than in those with type Ⅰ and 0. In plasmakinetic group, the operation time, absorption volume and volume of bleeding were significantly increased in type Ⅱ myoma patients. No significant difference was observed of Na~+, Cl~- and Glu concentrations between patients with the three types of myoma (P>0.05). Conclusion Plasmakinetic technique is superior to monopolar one in that it does not cause obvious changes in blood electrolytes and glucose and there is less bleeding during the operation. Myoma type has a greater effect on the absorption volume, operation time and volume of bleeding during operation, which are increased in type Ⅱ myoma than in type 0 and 1.

Objective:To knock the phospho-sugar mutase gene (psm) out of the genome of S. mutans strain UA159 and to construct the mutant will lay a foundation for the study of the function of the psm. Methods:Two upstream and downstream DNA sequences of the psm were selected and cloned respectively into multiple cloning sites I and II of suicide plasmid pFW5 to construct the recombinant plasmid which was confirmed by enzyme digesting and sequencing. The recombinant plasmid was transformed into S. mutans UA159 by natural transformation and antibiotic was used to screen the positive transformants. According to the principle of homologous recombination, allelic exchange between the recombinant plasmid and S. mutans UA159 was achieved. Results:By PCR analysis and sequencing, it was confirmed that the psm of S. mutans UA159 was substituted for resistant gene of spectinomycin. Conclusion: The psm-negative mutants of S. mutans UA159 is successfully constructed.

Objective To evaluate spectral CT imaging in characterizing the pathological type and the differentiation of gastric cancer.Methods Ninety-one patients diagnosed of gastric cancer were retrospectively analyzed.Patients were all underwent triple-phase enhanced scan using single source dualenergy CT on gemstone spectral imaging(GSI) mode.Three types of images were reconstructed for analysis:the water concentration (WC),iodine concentration (IC),and normalized iodine concentration (NIC).The patients were divided into groups of mucinous carcinoma (MUC),including mucinous adenocarcinoma and signet ring cell carcinoma,and non-mucinous gastric carcinoma (non-MUC).Independent-samples t test was used for statistical analysis.Results There were 24 patients of MUC and 67 patients of non-MUC.The IC and NIC of the non-MUC were significantly higher than the MUC in vein phase (VP) and in parenchymal phase (PP) [(21.33 ±6.31) × 100 vs (16.94 ±6.13) × 100 μg/ml,0.55 ±0.17 vs 0.42 ±0.14 in VP,and(20.65 ±5.49) × 100 vs (18.07 ±4.51) × 100 μg/ml,0.72 ±0.20 vs 0.57 ±0.12 in PP,respectively t =-2.948,-3.362,-2.261,-4.326,P ＜0.05].The IC and NIC of the signet ring cell carcinoma were statistically higher than those of the mucinous adenocarcinoma [(19.36 ± 4.75) × 100 vs (12.10 ±5.92) ×100μg/ml,0.49 ± 0.09 vs0.28±0.11 in VP,and (19.88±3.28) ×100 vs (14.45±4.62) ×100 μg/ml,0.63 ±0.08 vs 0.47 ±0.11 in PP,respectively t =3.253,5.180,3.339,3.850,P ＜0.01].For the poorly differentiated and well /moderately differentiated adenocarcinoma,the IC and NIC of the former were higher than those of the latter in VP and PP [(23.48 ±6.49) × 100 vs (18.98 ±5.26) × 100 μg/ml,0.61±0.16vs0.48±0.15 in VP,and (22.95±5.51) ×100 vs (18.28±4.47) ×100 μg/ml,0.81 ± 0.21 vs 0.63 ± 0.15 in PP,respectively t =3.098,3.249,3.766,4.117,P ＜ 0.01].The between-group differences of WC,IC and NIC in artery phase were no significant (P ＞ 0.05).Conclusions Different pathological types could determine different IC.The spectral CT imaging may be helpful for characterizing the pathological type of gastric cancer.

Objective To evaluate the value of MRI in qualitative and quantitative diagnosis of bone marrow involvement in patients with lymphoma. Methods 28 diagnosed lymphoma with bone marrow infiltration and 31 healthy spines as controls were included.MRI performance and the signal intensity ratio on T1WI (SIR1) of the spine bone marrow and cerebrospinal fluid were analyzed and statistical analyses were performed.Results Qualitative diagnosis among these patients,was shown than MRI results indicated that 27 cases had abnormal signal. The sensitivity of MRI was 96.4 ％. There were four main patterns of marrow infiltration in MRI,containing nodular pattern 21.4 ％ (6/28),scattered pattern 53.6 ％ (15/28),mottled pattern 14.3 ％ (4/28) and uniform pattern 7.1％ (2/28) respectively.By quantitative diagnosis the SIR1 of study group (1.251±0.253) was apparently lower than that in the control group (2.625±0.434) with statistical significance (t =15.022,P ＜ 0.001).The results of multiple comparisons showed that the SIR1 of mild degree (1.390±0.172),moderate degree (0.982±0.790) and severe degree (0.908±0.122) patients with lymphoma compared with the normal controls had significant differences (all P =0.000),and difference between mild and moderate degree had statistical significance (LSD,P =0.012),so did the difference between mild and severe degree (LSD,P =0.025).However,no significant difference could be seen between moderate and severe degree (LSD, P =0.757). Positive linear correlation was existed between the persentages of SIR1 and tumor cells in bone marrow (r =-0.765, P ＜ 0.001). Conclusion As a noninvasive and direct-viewing technique, MRI presents a global view of bone marrow with high sensitivity in detecting bone marrow involvement in lymphoma. To a certain extent, it could be possible to estimate the infiltration degree and evaluation of the tumor burden in bone marrow by quantitative measurement of MRI.

Objective To define a parameter of autologous arteriovenous fistula stenosis that limits the fistula function for hemodialysis in our country.Methods Retrospectively study the doppler ultrasound of patients who accepted the percutaneous transluminal angioplasty (PTA) therapy due to autogenous arteriovenous fistula dysfunction;identify the least diameter of the fistula vein and compare it with the corresponding data of well-functioned fistula.Determine which absolute diameter constitutes a hemodynamically significant stenosis in a radioeephalic autologous arteriovenous fistula by receiver operating characteristic curve (ROC curve).Result Forty-two patients were enrolled in the study.The average age of those patients was 54.63±2.44 years old.Twenty-one patients were female.Twenty-six fistula located on the left arm.The minimal diameter of the dysfunction fistula averaged 1.57±0.07 mm,while the average forearm fistula vein diameter was 4.04±0.23 mm,significantly smaller than those in the compare group-an average minimal fistula vein diameter of 3.34±0.11 mm and a forearm vein diameter of 5.36(4.52,6.45) mm (P ＜ 0.05).The control group contained sixty-eight patients.The average age of those patients was 52.56±2.00 years old.Thirty-one patients were female.Forty-nine fistula located on the left arm.It was quiet appropriate in using minimal diameter of the fistula vein to indicate the dysfunction istula with an under-curve area of 0.979,95％C1 0.959-0.998.The under-curve area would be at the largest level when meeting the cutoff point at 2.40mm,in which it could achieve the area of 0.853.Conclusions The minimal diameter of the dysfunction wrist autogenous arteriovenous fistula was much smaller than the functioned ones.Minimal diameter of the fistula vein may serve as an effective parameter in detecting dysfunction fistula.

OBJECTlVE To develop an LC-MS/MS method for simultaneous determination of pro-damine ( PDM) and its metabolite 2,4-dinitro-N3-propyl-6-trifluoromethyl-1,3-benzenediamine ( DTB) in rat plasma in order to study toxicokinetics of PDM in rats. METHODS SD male rats were administered a single dose of PDM ( ig: 100 and 1000 mg·kg-1; iv: 100 mg·kg-1 ) . LC-MS/MS method was used to determine PDM and DTB in rat plasma. Toxicokinetic parameters were fitted using DAS Ver2. 1. 1. RESULTS After ig administration of PDM 100 mg·kg-1 , the parameters of PDM and DTB were as fol-lows:AUC(0-t) was 2715±102 and (6845±316)μg·h·L-1, t1/2z was 9.0±1.4 and (7.1±1.3)h, Tmax was 7.0± 1.6 and (7.0±0.0)h, cmax was 146±51 and (473±103)μg·L-1. After ig administration of PDM 1000 mg·kg-1, the parameters of PDM and DTB were as follows:AUC(0-t) was 3401±242 and (10364± 573)μg·h·L-1, t1/2z was 8.8±2.1 and (6.0±1.8)h, Tmax was (7.0±1.6)h, cmax was 175±56 and (586± 152)μg·L-1 . The absolute bioavailability of PDM was 44.9%( 100 mg·kg-1 ) and 17.1%( 1000 mg·kg-1 ) . CONCLUSlON This method is suitable for the analysis of PDM and DTB in rat plasma. There is evidence that PDM and DTB display nonlinear toxicokinetic characteristics in the studied dose range.

Object To investigate the maturity status of the cephalic vein when the native arteriovenous fistula matures and set up indicators of a matured native arteriovenous fistula.Methods The diameter,flow rate and wall thickness of the cephalic vein were prospectively measured by Doppler ultrasound after the native fistula was created.Mature judgment was done by skilled nurses depending on their experience before the fistula was punctured.The ultrasound data was marked as proposed mature at the same time.After three times dialysis,if blood flow was fluent and complications such as prolonged bleeding time and hematoma were absent,fistula mature was confirmed.Results Thirty-one patients were admitted to the study,then fistula were matured.The average age of those patients was (52.93±3.21) years old.Thirteen patients were female.Twenty two fistula located on the left arm.Thirteen of the patients were diabetic nephropathy.The average diameter of cephalic vein was increased from (3.10±0.11) mm before surgery to (4.74±0.16) mm when the fistula was matured,though it was still smaller than 6 mm which K/DOQI guideline had recommended (P ＜ 0.05).The average mature period was (57.10±3.21) days.The matured fistula had an average high flow rate of (569.76±48.34) ml/min and wall thickness of (0.95±0.04) mm.The one-side 95％ credibility interval of the diameter,flow rate and wall thickness of cephalic vein was 4.44 mm,486.37 ml/min and 0.67 mm,respectively.Conclusions The diameter of cephalic vein in a matured native arteriovenous fistula in our study was significantly smaller than 6 mm which K/DOQI guideline had recommended.The indicators of native arteriovenous fistula mature in our country may different from abroad.

Objective To analyze the relationship between the least diameter of autogenous arteriovenous fistula and other parameters like flow rate and artery diameter. To identify an appropriate way in defining fistula stenosis. Methods Physical examination and Doppler ultrasound were used to examine the autogenous arteriovenous fistula of maintenance hemodialysis patients. Well?used wrist arteriovenous fistula was included. The least diameter of the fistula vein was found and marked by ultrasound, and the diameter and the distance between the point and the anastomotic stoma were measured. Diameters of different places along the cephalic vein of the fistula, including the forearm place, the place close to elbow and the upper arm place were measured by ultrasound. Meanwhile, diameter as well as flow velocity and flow rate of brachial artery, radial artery and ulnar artery were also measured. Result Sixty?eight patients were enrolled in the study. The average age of those patients was 52.56 ± 2.00 years old. Thirty?one patients were female. Forty?nine fistula were located on the left arm. The average diameter and flow rate of brachial artery were 5.72(5.34, 6.33) mm and 821.50 (540.50, 1075.00) ml/min, respectively. The average diameters of radial artery and ulnar artery were 3.95 ± 0.10mm and 3.17(2.73,3.75) mm, respectively. The least diameter of cephalic vein was 3.34 ± 0.11mm in average. The distance between the least place to the anastomotic stoma was 3.76±0.14cm in average. The diameter of forearm cephalic vein was averaged 5.36(4.52, 6.45) mm. Diameter of place close to elbow and the upper arm place in the cephalic vein were (5.57±0.12) mm and (5.80±0.14) mm, respectively. The least diameter of cephalic vein was positively and statistically associated with the diameter and flow rate of brachial artery as well as radial artery. The least diameter was also positively and statistically associated with the diameter of each place in the cephalic vein. Statistical inter?group difference was found when the division was based on the value of the least diameter. Conclusion sThe least diameter of the wrist autogenous arteriovenous fistula vein will indeed affect the whole diameter and flow rate of the fistula. The value of the least diameter is more closely associated with the fistula function rather than narrow rate.

Objective To investigate the predictive value of early diffusion-weighted imaging (DWI) for early neurological deterioration (END) after acute isolated basal ganglia infarct.Methods Patients with acute isolated basal ganglia infarct in middle cerebral artery perforators completed head MRI examination at 24 h after onset were analyzed retrospectively.According to the axial DWI revealed lesion size,the maximum diameters were divided into ＜ 15 mm,15-30 mm,and ＞ 30 mm.END was defined as an increase in the National Institute of Health Stroke Scale (NIHSS) score ≥2 or the motor score of NIHSS ≥ 1 at any time within the first 72 h after admission compare with the baseline scores.Results A total of 336 patients were enrolled,including 126 patients (37.5％) with END.There were significant differences in the constituent ratios of the sex (P =0.044),maximum diameter of the lesion (P =0.001),and guilty artery stenosis (P =0.006),as well as baseline NIHSS score (P =0.001),high-density lipoprotein cholesterol (HDL-C) (P =0.033),and C-reactive protein (P =0.039) between the END group and the non-END group.Multiple logistic regression showed that the maximum diameter of the lesions 15-30 mm (odds ratio [OR] 2.360,95％ confidence interval [CI] 1.370-4.066;P =0.002),female (OR 1.660,95％ CI 1.024-2.691;P =0.040),and guilty large artery stenosis (OR 1.713,95％ CI 1.036-2.833;P =0.036) were the independent risk factors for patients occurring END,while the high HDL-C (OR 0.355,95％ CI 0.141-0.894;P =0.028) was an independent protective factor of occurring END.Conclusion Early DWI revealed that the maximum diameter of the lesions may have certain clinical value for prediction of the occurrence of END in patients with acute isolated basal ganglia infarct.