Objective Streptococcus sanguis is a possible candidate bacterium for the caries replacement therapy, which has no advantages in the acidic environment.The aim of the study was to construct acid-resistant strains of Streptococcus sanguis, determine its acid tolerance, and explore the mechanism of its antagonism against Sterptococcus mutans.Methods By gradually reducing the pH value of the medium, we constructed acid-resistant strains of Streptococcus sanguis, observed their growth and measured their acid tolerance according to their survival rate against lethal pH.We evaluated the competitive relationship between Streptococcus sanguis and Streptococcus mutans by plate experiment and detected the changes of related acid resistance genes by real-time quantitative PCR.Results The growth of Streptococcus sanguis and its acid-resistant strains were limited by the pH value, and that of Streptococcus sanguis was better in either acidic or normal environment.The lethal pH value of Streptococcus sanguis was 3.6, that of its acid-resistant strains was 2.3, and the survival rate of the acid-resistant strains was 66.59% in the pH 3.6 environment.In comparison, the lethal pH value of Streptococcus mutans was 2.5, that of its acid-resistant strains was 2.1, and the survival rate of the acid-resistant strains was 2.55% in the pH 2.5 environment.In the presence of chloramphenicol, the acid-resistant strains could not survive in the original lethal pH.In the sub-lethal pH environment, the expressions of the acid resistance-related genes Groel and Dnak in the acid-resistant strains were significantly up-regulated as compared with those in the original Streptococcus sanguis (P<0.05).Conclusion Streptococcus sanguis has an acid adaptability and can enhance acid resistance in the sub-lethal pH environment.Acid-resistant Streptococcus sanguis in the replacement therapy may provide some new ideas for the treatment of dental caries.

Objective To study the profiles and function of small RNA (sRNA)gene during chondrogenesis in rats so as to clarify the mechanisms of chondrocytes proliferation and differentiation.Methods All the sRNAs were identified from the female SD rats femoral head cartilages at three time points:at birth,ablactation and maturation,and three sRNA libraries were constructed.The Solexa sequencing and the bioinformatics analysis were employed to be blasted with the genomes of SD rats.Results The perfect match reads in the three libraries were screened out,which were correspondent to the 21 7 921 (41.23%),1 96 650 (38.74%)and 245 436 (41.54%)unique sRNA sequence,respectively.The percentages of 20-24 nt sRNA were 71.94% (d0),72.85% (d21),and 86.39%(d42).Half of clean sequences were 22 nt sRNA.The distribution characteristics of the reads were in line with the high-quality sRNA.More than 62% clean reads were from mature miRNA while the ratios in the three libraries were only 0.69%,0.78% and 0.63%.About 60% of the unique sRNA could not be matched with miRBase20.0 or Rfam9.1.Conclusion The distribution model of miRNA in the three libraries indicates that the miRNAs with different functions or from different sources are involved in the regulation of chondrocytes proliferation and differentiation in bone development and formation.

Objective:To investigate the difference of accuracy between magnetic induction Freehand-3D ultrasound and two-dimensional ultrasound in measuring the volume of thyroid model.Methods:Forty thyroid models were established using porcine liver, and the Archimedes procedure was set as gold standard in the measurement of the volume of each model. The accuracy of measurement of the porcine thyroid model volume between two-dimensional ultrasound and magnetic induction Freehand-3D ultrasound were compared.Results:There were no significant differences in the accuracy of measurements of thyroid model volume among two-dimensional ultrasound, magnetic induction Freehand-3D ultrasound and Archimedes procedure (all P>0.05). Compared with the Archimedes procedure, magnetic induction Freehand-3D ultrasonic method showed higher correlation coefficient of the measurement of thyroid model volume ( r=0.998). Bland-Altman analysis showed the lower measure error with a relative error of 3.42% and range of -9.57% to 12.07%. And the limits of agreement were (-1.253, 0.999) in the magnetic induction Freehand-3D ultrasonic measurement. Conclusions:Compared with two-dimensional ultrasound, the magnetic induction Freehand-3D ultrasound show higher accuracy in the measurement of the volume of the thyroid model.

AIM:To study the effects of noninvasive delayed limb ischemia preconditioning ( NDLIP) on ani-mal cardiac function , myocardial morphology and myocardial apoptosis after myocardial infarction ( MI ) .METHODS:Healthy SD male rats [n=45, weighing (250 ±10) g] were randomly divided into 3 groups:MI group:the animal model of MI was established by surgical ligation of left anterior descending artery ( LAD) after 2 weeks;NDLIP group:after the success of the MI animal model , NDLIP was carried out every other day until the 4th, 6th and 8th weeks;sham group:as the negative control group , the animals were taken heart LAD threading but no ligation .All rats were fed conventionally .At the end of the 4th, 6th and 8th weeks, all rats were made ventricular intubation , and then the hemodynamic parameters were recorded .The blood samples were withdrawn from the abdominal aorta and the serum was separated via centrifugation . The serum contents of Bcl-2 and Bax were measured by ELISA .Left ventricular anterior wall was homogenized .The mito-chondrial respiratory chain complexes Ⅰ,Ⅱ,Ⅲand Ⅳin the myocardial tissues were detected by ELISA .RESULTS:At the end of the 4th, 6th and 8th weeks, compared with MI group, left ventricular systolic pressure in NDLIP group was significantly increased , while left ventricular end-diastolic pressure in NDLIP group was significantly decreased ( both P<0.05).Mitochondrial respiratory chain complexesⅠ, Ⅱ, Ⅲ and Ⅳ in NDLIP group were significantly increased (P<0.05).The serum level of Bcl-2 in NDLIP group was significantly increased and Bax level was reduced remarkably (both P<0.01) .CONCLUSION:NDLIP improves the hemodynamic indexes , promotes the mitochondrial respiratory function and inhibits cell apoptosis , thus improving the prognosis of MI .

Aim To study the preventative effects of noninvasive delayed limb ischemic preconditioning ( NDLIP) on sudden cardiac death in rats with myocar-dial infarction. Methods Thirty healthy SD male rats weighting ( 250 ± 10 ) g were randomly divided into 3 groups:① myocardial infarction ( MI ) group: animal model of MI was established by making surgical ligation of animal LAD. ② MI plus NDLIP group: after the success of the animal model of MI, NDLIP was carried out every other day until 4th week. ③Sham group:as the negative control group, animals were taken heart LAD threading but no ligation. All rats were fed con-ventionally. At the end of 4 weeks, three groups of rats were administered with metaraminol ( 0. 2 mg · min-1 ) . ECG, drug cumulant of sudden death and death onset time were recorded. After sudden death, blood samples were withdrawn from abdominal aorta and serum was separated via centrifugation. ELISA method was used to measure serum caspase-3 , HSP70 and SOD concentration. Results While metaraminol led animal cardiac sudden death, the rats heart rate ( HR) kept declining with the increase of dosage of metaraminol during the administration period. Rat HR of MI+NDLIP group [ ( 479 ± 8 ) vs ( 416 ± 19 ) beat ·min-1 , ( 446 ± 32 ) vs ( 370 ± 20 ) beat · min-1 , (376 ± 53) vs (305 ± 29) beat·min-1, (307 ± 63) vs (244 ± 33) beat·min-1, (283 ± 45) vs (121 ± 35 ) beat · min-1 , P <0. 01 ] was markedly higher than that of MI group at 0 , 5 , 10 , 30 , 50 min before death. Compared with MI group, drugs cumulant to sudden death and death onset time of MI + NDLIP group [ ( 14. 58 ± 3. 03 ) vs ( 10. 76 ± 2. 73 ) mg, (72. 9 ± 15. 2 ) vs ( 53. 8 ± 13. 6 ) min, P <0. 01 ] were significantly increased. Compared with MI group, serum caspase-3 content of MI+NDLIP group was sig-nificantly reduced [ ( 2. 01 ± 0. 52 ) vs ( 2. 34 ± 0. 38 )μg·L-1 , P<0. 01 ]; HSP70 levels were remarkably increased [ ( 3. 01 ± 0. 58 ) vs ( 2. 70 ± 0. 43 ) μg · L-1 , P <0. 05 ]; SOD levels were significantly im-proved [(1. 99 ± 0. 65) vs (1. 70 ± 0. 58) mg·L-1, P<0. 01 ] . Conclusion NDLIP can prevent sudden cardiac death after myocardial infarction in rats, which may be mediated by reducing the myocardial cell apop-tosis, increasing protective protein expression and en-hancing antioxidant capacity.

The burden of cardiovascular disease in China is severe and keep increasing nowadays, while effective dietary management strategies play an important role in its primary prevention and treatment. Flaxseed is rich in lots of bioactive components like α-linolenic acid, lignan, linseed bioactive protein fragments and fi-ber, which can effectively improve a variety of heart risk factors like atherosclerosis, obesity and abnormal blood glucose, and thus has become a hot spot in researches of dietary strategies for cardiovascular diseases. As a po-tential heart-friendly food, cardiovascular-protective effects of flaxseed are particularly prominent in blood pres-sure control and lipid regulation. This article reviewed recent clinical controlled trials studying effects of flaxseed on both blood pressure and lipid profiles in different populations, and its potential hypotensive as well as lipid-lowering mechanisms, in order to lay a solid foundation for further studies.

Objective To analyse the prognosis of 117 newly diagnosed nasopharyngeal carcinoma (NPC) patients underwent intensity modulated radiotherapy (IMRT). Methods From Jan to Nov 2005, 117 NPC patients who were treated by IMRT were enrolled. There were 81 males and 36 females with a median age of 42 years (range 18-76 years). According to Chinese Fuzhou Staging system(1992), 11 cases were Stage I , 15 Stage Ⅱ, 54 Stage Ⅲ and 37 Stage ⅣA. IMRT was carried out with Peacock plan. The prescription dose to the gross target volume(GTVnx) of nasopharyngeal tumor was 68 Gy, that of positive neck lymph nodes (GTVnd) was 60-66 Gy, clinical target volume 1 (CTV1) was 60 Gy, and CTV2 was 54 Gy. Results After a median follow-up time of 48 months (range 10.5-59.5 months), the 3-and 5-year overall survival (OS) rates were 95.7 % and 89.7 %, the disease-free survival (DFS) rates were 91.5 % and 87.2%, and the local-regional control rates were 94.0 % and 91.5 %. Univariate analysis showed the KPS, stage, Fuzhou clinical stage, status of blood platelet before treatment and uric acid after treatment were correlated with OS rate. T stage was the only independent factor of prognosis in the COX stepwise regression model. Conclusion Radical IMRT significantly prolongs the survival of NPC patients. T stage is the only independent prognostic factor for NPC patients.

Objective To evaluate left ventriclular systolic function in patients with obstructive hypertrophic cardiomyopathy (HOCM) after modified Morrow surgery using two-dimensional speckle tracking imaging (2D-STI).Methods Twenty three HOCM patients were recruited in this study.Echocardiographic data from HOCM patients during pre-operation,1-month and 3-month post-operation were analyzed by Qlab software to compare the variation in systolic function indicators 1-month and 3-month post-operation including global and 16 segmental longitudinal strain,circumferential strain and conventional echocardiographic parameters of left ventricle.Results Compared with preoperative data of HOCM patients,postoperative LVOT diameter and pressure gradient,left atrial diameter and volume index were significantly decreased(P<0.05),but there was no significant difference in left ventricular ejection fraction(P<0.05).Compared with the preoperative case,global and segmental longitudinal strain showed significant reduction after 1 week and gradually recovered after 3 months,without significant variation.The longitudinal strain of the anteroseptum reduced significantly and the longitudinal strain of the free wall increased after 3 months,however,the circumferential strain reduced significantly.The circumferential strain of basal and middle segment after 3 months had improved significantly than those of postoperative 1 week.The circumferential strain of surgical site is no obvious change and the strain of free wall was improved after 3 months.Conclusions 2D-STI can effectively evaluate global and regional systolic function of left ventricle for HOCM patients after modified Morrow surgery.

Objective To analyze the characteristic of Yunnan unexpected sudden death (YUSD) cases by pathological diagnosis of arrhythmogenic right ventricular cardiomyopathy (ARVC),in order to offer clue for ARVC etiologic research of YUSD.Methods The pathological diagnosis results of 9 cases of sudden death of ARVC in Yunnan,as well as epidemiological investigation data,were used to comprehensively analyze the pathological features of the pathological diagnosis of ARVC in Yunnan.Results The 9 cases including 8 females and 1 male,aged 16-47 years.The sudden death time was from June to August,mainly distributed in 8 families from the disease seriously ridden 7 villages.Three of them had a genetic history of family YUSD,2 cases had a history of mental stimulation,1 case had eaten Trogia venenata;and acute symptoms and signs were palpitation,chest tightness,shortness of breath,and loss of consciousness.Pathological observations were the typical ARVC change,mainly right ventricular lesions,with different degrees of cardiac enlargement and extensive adipose tissue infiltration in the ventricular wall.Among them,6 cases of fat infiltration almost reached the full thickness of the heart wall.In addition to the pathological changes of ARVC,8 cases were accompanied by one or several pathological changes in myocarditis,cardiac dysplasia,nephropathy,pulmonary edema,pneumonia and pancreatitis.Of the 9 cases,5 cases were diagnosed with ARVC,2 cases with ARVC and pulmonary edema,1 case with ARVC and acute hemorrhagic necrotizing pancreatitis,and 1 case with ARVC and Trogia venenata poisoning.The clinical examination abnormalities of the family members of the cases mainly showed arrhythmogenic electrocardiography changes and abnormal myocardial enzymes.Conclusions The nine cases have showed typical epidemiology characteristics of YUSD,and cardiachistological changes are consistent with the ARVC pathological diagnostic criteria.A part of YUSD cases may be caused by ARVC,and the inference will be proved by cadaveric pathologic examination and related pathogenic gene detection.

Gastric cancer, a common malignant tumor in digestive system with high morbidity as well as mortality rate, is insidious at the onset and lack of effective treatments so far. A growing number of studies have shown that exosome-derived miRNAs play an important role in the occurrence and development of gastric cancer. Autocrine exosome miRNAs from gastric cancer cells regulated tumor growth, recurrence, metastasis and drug resistance, etc. Moreover, exosomal miRNAs in the tumor microenvironment can be delivered into cancer cells to facilitate intercellular communication, thus affecting the progress of gastric cancer. Due to exosomes, which were released into circulation from tumor cells, contain abundant, specific and stable miRNAs, exosome-derived miRNAs have a great potential to be used as novel diagnosis biomarkers and treatment targets of gastric cancer.(Chin J Lab Med, 2018, 41: 499-502)