[The relationship between homocysteine, coagulation dysfunction and breast cancer risk].

Objective: To investigate the correlation of homocysteine (HCY) and coagulation function index with the risk of breast cancer and its clinicopathological characteristics. Methods: The HCY, coagulation function test index, and clinicopathological information of female breast cancer patients (333 cases) treated in Tianjin Medical University Cancer Hospital from January 2018 to December 2018 were collected, and female patients with benign breast (225 cases) were selected during the same period for the control group. The t-test was used to compare measurement data with normal distribution, D-Dimer data were distributed discreetly and described by median, non-parametric Mann-Whitney U test was used to compare the two groups. The chi-square test was used to compare enumeration data, and the Logistic regression analysis was used for the risk analysis. Results: The levels of HCY, fibrinogen (Fbg), protein C (PC), and median D-Dimer (D-D) in peripheral blood of breast cancer patients group [(13.26±5.24) µmol/L, (2.61±0.83) g/L, (117.55±19.67)%, and 269.68 ng/ml, respectively] were higher than those in the control group [(11.58±0.69) µmol/L, (2.49±0.49) g/L, (113.42±19.82)% and 246.98 ng/ml, respectively, P<0.05]. The prothrombin time (PT), PT(INR), α2-antiplasmin (α2-AP) levels [(10.19±0.63) s, 0.91±0.07 and (110.64±13.93)%, respectively] were lower than those in the control group [(10.58±0.65) s, 0.93±0.01 and (123.81±14.77) %, P<0.05]. The serum levels of PC and median D-D in premenopausal breast cancer patients [(112.57±17.86)% and 242.01 ng/ml, respectively] were higher than those in the control group [(105.31±22.31)% and 214.75 ng/ml, respectively, P<0.05]. The levels of PT(INR), α2-AP [0.91±0.07 and (111.29±12.54)%, respectively] were lower than those of the control group[0.98±0.15 and (120.17±16.35)%, respectively, P<0.05]. The levels of HCY and median D-D in postmenopausal breast cancer patients [(14.25±5.76) µmol/L and 347.53 ng/ml, respectively] were higher than those in the control group [(11.67±2.38) µmol/L and 328.28 ng/ml, P<0.05]. The levels of PT, PT(INR), antithrombin Ⅲ (AT-Ⅲ), α2-AP levels [(10.18±0.66) s, 0.87±0.09, (97.30±12.84)% and (110.13±14.96)%] were lower than those in the control group [(10.38±0.61) s, 0.90±0.08, (102.89±9.12)%, and (127.05±12.38)%, respectively, P<0.05]. The levels of α2-AP and median D-D in T2-4 stage breast cancer patients [(111.69±14.41)% and 289.25 ng/ml, respectively] were higher than those in Tis-1 stage patients [(108.05±12.37)% and 253.49 ng/ml, respectively, P<0.05]. The levels of PT, PT (INR), Fbg, AT-Ⅲ, α2-AP, median D-D [(10.62±0.63) s, 0.95±0.06, (3.04±1.52) g/L, (103.21±9.45)%, (118.72±14.77)% and 331.33 ng/ml, respectively] in breast cancer patients with lymph node metastasis were higher than those of patients without lymph node metastasis [(10.42±0.58) s, 0.93±0.06, (2.52±0.54) g/L, (95.20±13.63)%, (106.91±13.13)% and 263.38 ng/ml, respectively, P<0.05]. In non-menopausal breast cancer patients, the level of HCY [(12.63±4.41) µmol/L] in patients with T2-4 stage was higher than that of patients with Tis-1 stage [(10.70±3.49) µmol/L, P=0.010], and the level of thrombin time [(19.35±0.90) s] of patients with T2-4 stage was lower than that of patients with Tis-1 stage [(19.79±1.23) s, P=0.015]. The levels of PT(INR), Fbg, AT-Ⅲ, α2-AP [0.97±0.56, (3.37±2.34) g/L, (102.38±8.77)% and (120.95±14.06)%] in patients with lymph node metastasis were higher than those of patients without lymph node metastasis [0.94±0.05, (2.36±0.48) g/L, (94.56±14.37)% and (109.51±11.46)%, respectively, P<0.05]. Among postmenopausal breast cancer patients, the levels of AT-Ⅲ and α2-AP in T2-4 stage patients [(98.48±11.80)% and (111.84±15.35)%, respectively] were higher than those in patients with the Tis-1 stage [(94.12±14.98)% and (105.49±12.89)%, respectively, P<0.05]. The levels of AT-Ⅲ and α2-AP in N1-3 stage patients [(103.74±9.94)% and (117.29±15.23)%] were higher than those in N0 stage patients [(95.75±13.01)% and (108.39±14.42)%, P<0.05]. Conclusions: HCY and abnormal coagulation function are related to the risk of breast cancer, T stage and lymph node metastasis in breast cancer patients.

[Mechanism of Mycobacterium tuberculosis on interleukin-6 receptor 3'-untranslated region methylation in CD4+T cells].

Objective: To investigate the role and mechanism of DNA methylation in Mycobacterium tuberculosis (MTB lysate) -induced downregulation of interleukin-6 receptor(IL-6R) expression in CD4+T cells. Methods: A prospective study was conducted. Bisulfite sequencing (BSP) was applied to determine the methylation levels of CpG island in IL-6R promoter region and 3'untranslated region (3'UTR) region in CD4+T cells from peripheral blood mononuclear cells (PBMC) of control group (healthy person, n=10) and TB group (tuberculosis patients, n=10) in Shenzhen Third People's Hospital between 2019 and 2020. Quantitative reverse transcription-PCR (RT-qPCR) and Western blotting were used to detect the expression of IL-6R, DNMT1, DNMT3A and DNMT3B in MTB lysate-stimulated CD4+T cells and Jurkat E6-1 cells. Furthermore, PBMC in control group and Jurkat E6-1 cells activated by anti-CD3/CD28 antibody were stimulated by MTB lysates to detect the methylation levels of CpG island and IL-6R and DNMT expression. Transcriptional activity of differently methylation regions of IL-6R 3'UTR was detected by using luciferase reporter gene system. Results: IL-6R expression in TB group was lower than that in control group, but DNMT1 and DNMT3B expressions were higher than those in control group in CD4+T cells isolated from PBMC. There was no significant difference in the methylation rate of IL-6R promoter CpG island of CD4+T cells between control and TB group. However, the methylation rates of CpG island in 3'UTR region were significantly higher (P<0.001) in TB (69.5%±3.4%), compared with control (54.3%±4.7%). Besides, IL-6R expression was lower than unstimulated, while DNMT1 and DNMT3B expression was higher than unstimulated after MTB lysate-stimulation of activated control PBMC in vitro. The methylation rate of CpG island in IL-6R 3'UTR region of CD4+T cells increased from 58.8%±11.6% to 79.4%±10.9% (P<0.001) after MTB lysate-stimulated PBMC of the control. The same results were observed in the MTB lysate-stimulated CD4+T cells isolated from PBMC in control and Jurkat E6-1 cell line. Furthermore, IL-6R expression after co-treatment of the DNA methyltransferase inhibitor decitabine (5-aza) with MTB lysate was higher than that stimulated by MTB lysate alone. In addition, the methylation levels of CpG islands in the 3' UTR region of IL-6R were lower than those stimulated by MTB lysates alone after co-treatment of the DNA methyltransferase inhibitor decitabine (5-aza) with MTB lysates. The transcriptional activity of the fully unmethylated IL-6R 3'UTR CpG island reporter gene was higher than that of the fully methylated IL-6R 3'UTR CpG island. Conclusions: MTB lysates stimulation inhibited IL-6R expression transcriptionalely as well as on the protein level by inducing hypermethylation of CpG island in IL-6R 3'UTR region of CD4+T cells. The hypermethylation of CpG island in IL-6R 3'UTR region of CD4+T cells induced by MTB may be related to the increased expression of DNMT1 and DNMT3B.

[Survey on tobacco use and associated factors in population in Shandong province, 2016-2017].

Objective: To understand the status of tobacco use and related influencing factors in population in Shandong province. Methods: Stratified multi-stage cluster sampling was used to select respondents from 216 villages (communities) of 36 districts (counties) in Shandong province. Influencing factors on smoking were analyzed by logistic regression model. Results: The adequate sample size was 6 271 participants. After complex weighted, the current smoking prevalence was 23.93%,45.58% in males and 1.18% in females. The Public's smoking rates varied widely among different groups in the population. 45-64 age group had the highest smoking rate (25.07%). Smoking rates were substantially different in education levels, with the highest in junior high school (28.94%). The rate was higher in the rural area (24.98%) than that in the urban areas (23.08%). The average daily smoking rate was 20.23%. The average age of initiating smoking was 21.21 years. The average daily cigarette intake was 16.31 cigarettes. Among all the former and current smokers, the quitting rate was 20.79%. Multiple logistic regression model analysis showed that gender, age, occupation, region, and health knowledge score were correlated with smoking behavior. The current smoking rate of men was much higher than that of women (OR=49.625, 95%CI: 37.832-65.093). The current smoking rate in 45-64 age group was higher than that in the 15-24 age group (OR=1.830, 95%CI: 1.048-3.194). The current smoking rate of medical (OR=0.403, 95%CI: 0.187-0.866) and retired personnel (OR=0.648, 95%CI: 0.481-0.873) were lower than those engaging in agriculture, forestry, animal husbandry and the fishery ,respectively. The prevalence of residents living in the central part showed lower rate on current smoking than that in the eastern region (OR=0.724, 95%CI: 0.606-0.865). The current smoking prevalence of smoke hazard in 1-3 score group was higher than that in the group with 4-6 score (OR=1.432, 95%CI: 1.240-1.654). Conclusions: Smoking rate in adults in Shandong remained stable and at a high level. Comprehensive intervention measures such as tobacco control and health education should be carried out to reduce the smoking rate.

[Study on the relationship between smoking behavior and health literacy among grade 4-6 primary students in Shandong province].

Objective: To investigate the associations between smoking and literacy on health among 4-6 grade primary school students. Methods: A questionnaire survey was conducted to research on health literacy and smoking among 4-6 grade pupils in Shandong province, through a multi-stage stratified cluster random sampling method. Sociodemographic characteristics, health literacy level and smoking rate were collected from respondents. Binary logistic regression analysis was used to evaluate the association of smoking and health literacy. Results: A total of 9 240 questionnaires were distributed, with the rate of valid response as 99.7%. The current smoking rate of the students was 2.6%, on higher in boys (3.1%) than in girls (2.0%). 60.8% of 4-6 grade students were found to have adequate health literacy level. Levels of literacy health in both boy and girl school students appeared 56.7% and 64.9%, respectively. Results indicated that health literacy in smokers (14.4%) was lower than that in non-smokers (62.0%). Results from the binary logistic regression analysis showed that the independent influencing factors would include grade, father's education level, economic situation of the family, self-assessment on the school record and literacy on health (P<0.01). After controlling the other independent variables, the smoking rate was 8.62 (1/0.116) times in students with low literacy level on health, than those with high literacy level. Conclusions: Literacy on health was significantly associated with smoking in the 4-6 grade pupils of Shandong province.

Overexpression of EPS8L3 promotes cell proliferation by inhibiting the transactivity of FOXO1 in HCC.

The homology of epidermal growth factor receptor pathway substrate 8 (EPS8), EPS8L3, is elevated significantly in hepatocellular carcinoma (HCC) tissues and cell lines compared with the normal liver tissues and cell lines. The MTT and colony formation assays demonstrated that overexpressing EPS8L3 enhances, while silencing reduces the proliferation of HCC cells. Further experiments illustrated that overexpressing EPS8L3 promotes the expression of p-AKT, Cyclin D1, but inhibits the transcriptional activity of FOXO1. Besides, colony formation assay demonstrated that AKT inhibitor suppresses the effect of EPS8L3 on proliferation in EPS8L3-overexpressing cells, whereas AKT restores the proliferation of EPS8L3-silenced cells, suggesting that EPS8L3 might promote proliferation by hyperactivating the AKT signaling pathway and subsequently inhibiting the FOXO1 transcriptional activity. Our results provide new view between EPS8L3 and progression of human HCC, suggesting that EPS8L3 may be a novel therapeutic target for HCC.

[Clinicopathological and ultrasound characteristics of extranodal extension in metastatic papillary thyroid carcinoma patients].

Objective: To explore clinicopathological and ultrasound characteristics of extranodal extension in metastatic papillary thyroid carcinoma patients. Methods: 176 patients with papillary thyroid carcinoma who were diagnosed in Tianjin Medical University Cancer Institute and Hospital between March 2011 and March 2016 were identified and recruited in the study. Among the 176 patients, 59 patients were diagnosed with regional lymph nodes metastasis accompanied with extranodal extension (extranodal extension positive group), 117 patients were regional lymph nodes metastasis without extranodal extension (extranodal extension negative group). The clinicopathological and ultrasound characteristics between extranodal extension positive group and extranodal extension negative group were also discussed in this article. Results: 59 patients were diagnosed with regional lymph nodes metastasis accompanied with extranodal extension (extranodal extension positive group). Single lymph node region of extranodal extension was identified in 40 patients, while 19 patients were confirmed with more than 2 regions of extranodal extension. The most frequent extranodal extension were detected in region Ⅵ lymph nodes(32 cases), following by Ⅲ(25 cases), Ⅳ(16 cases), Ⅱ(11 cases). In the aspect of ultrasound characteristics, metastatic papillary thyroid carcinoma with extranodal extension showed a higher incidence of node matting[13.6%(8/59) vs 3.4%(4/117), P=0.022], micro-calcification[66.1%(39/59) vs 46.2%(54/117), P=0.016], cystic[28.8%(17/59) vs 12.8%(15/117), P=0.013], aspect ratio(L/S)<2[88.1%(52/59) vs 75.2%(88/117), P=0.032] and larger diameter(1.95±1.01 cm vs 1.63±0.94 cm, P=0.028). Logistic multivariate analysis demonstrated that node matting (P=0.025) and cystic (P=0.026) were independent risk factors for extranodal extension. Conclusion: Node matting, micro-calcification, cystic, aspect(L/T)>2 and larger diameter were associated with extranodal extension in metastatic papillary thyroid carcinoma patients, especially node matting and cystic, which might help topre-operative ultrasound diagnosis of extranodal extension.

Structural and dynamical characteristics of flow units in metallic glasses.

The metallic glasses (MGs) are conjectured to be heterogeneous-their microscopic structures are embedded with localized, soft and loosely packed atomic regions, which are termed as flow units (FUs). Detailed knowledges on the structure and dynamical features of FUs are essential for understanding the plasticity of MGs. In our study, by performing dynamical tests on MGs in molecular dynamics simulations, we show that mechanical hysteretic loops are formed in the strain-stress curves due to the undergoing plastic events. By analyzing the activated times of each atom in different dynamical tests, we map the exact locations of FUs and the distribution of their activation probability in the initial structure of MGs. More importantly, we demonstrate that the FUs are indeed liquid-like according to the Lindemann criterion of melting.

Mechanical Relaxation-to-Rejuvenation Transition in a Zr-based Bulk Metallic Glass.

The relaxation of amorphous materials, i.e., aging, would largely endanger their performances in service. Here we report a mechanical relaxation-to-rejuvenation transition of a Zr35Ti30Be27.5Cu7.5 bulk metallic glass (BMG) in elastostatic compression at ambient temperature, thus provide an accessible way to tailor the mechanical properties of amorphous materials. To unravel the structural evolution underlying the observed transition, atomistic simulations parallel with the experimental tests on a typical model glass system Zr60Cu40 were performed, which successfully reproduced and thus upheld the experimentally observed mechanical relaxation-to-rejuvenation transition. The variations of coordination number and atomic volume during the transition are evaluated to indicate a de-mixing tendency of the constituent atoms in the rejuvenation stage. This de-mixing tendency largely explains the difference between mechanical rejuvenation and thermal rejuvenation and reveals a competitive relationship between activation enthalpy and activation entropy in the stress-driven temperature-assisted atomic dynamics of BMG, such as diffusion and plastic deformation etc.

[A case of congenital cyst of epiglottis caused by severe upper respiratory tract obstruction].

The main clinical manifestations were respiratory distress，perioral cyanosis and Upper respiratory obstruction symptoms.The epiglottis opened by laryngoscope,can see a gray white semi elliptical sacs.Clinical diagnosis:congenital cyst of epiglottis.

Critical scaling of icosahedral medium-range order in CuZr metallic glass-forming liquids.

The temperature evolution of icosahedral medium-range order formed by interpenetrating icosahedra in CuZr metallic glassforming liquids was investigated via molecular dynamics simulations. Scaling analysis based on percolation theory was employed, and it is found that the size distribution of clusters formed by the central atoms of icosahedra at various temperatures follows a very good scaling law with the cluster number density scaled by S-τ and the cluster size S scaled by |1 - Tc/T|-1/σ, respectively. Here Tc is scaling crossover-temperature. τ and σ are scaling exponents. The critical scaling behaviour suggests that there would be a structural phase transition manifested by percolation of locally favoured structures underlying the glass transition, if the liquid could be cooled slowly enough but without crystallization intervening. Furthermore, it is revealed that when icosahedral short-range order (ISRO) extends to medium-range length scale by connection, the atomic configurations of ISROs will be optimized from distorted ones towards more regular ones gradually, which significantly lowers the energies of ISROs and introduces geometric frustration simultaneously. Both factors make key impacts on the drastic dynamic slow-down of supercooled liquids. Our findings provide direct structure-property relationship for understanding the nature of glass transition.

Validation of associations between ESR1 variants and breast cancer risk in Chinese cohorts.

Estrogen receptor-a (ER) protein plays a key role in breast carcinogenesis, and common genetic variants in the corresponding gene locus have been associated with breast cancer risk in different populations. Here, we analyzed estrogen receptor 1 (ESR1) associations in two hospital-based studies of patients from the south of China. Three single-nucleotide polymorphisms (SNPs; rs3757318, rs2046210, and rs3734805) in ESR1 were selected from previous genome-wide association study results and were genotyped using the Sequenom MassARRAY® iPLEX System in 845 breast cancer patients and 882 healthy controls. Association analysis based on unconditional logistic regression was carried out to determine the odds ratio (OR) and 95% confidence interval (95%CI) for each SNP. Stratified analyses according to the status of ER and progesterone receptor (PR) were also performed. Of the three SNPs, rs3757318 did not pass the Hardy-Weinberg equilibrium test and was excluded from the subsequent analysis. The other two SNPs (rs2046210 and rs3734805) were strongly associated with susceptibility to breast cancer. Allele T of rs2046210 and allele C of rs3734805 were risk alleles and the adjusted ORs were 1.348 (95%CI = 1.172-1.550, P = 0.0001) and 1.319 (95%CI = 1.144-1.522, P = 0.0001), respectively. Furthermore, the risk allele of rs2046210 gave negative results for ER and PR expression in an immunohistochemical test, with ORs of 0.602 (95%CI = 0.384-0.944, P = 0.027) and 0.532 (95%CI = 0.338-0.837, P = 0.006), respectively. Our study further supports associations between rs2046210 and rs3734805 and breast cancer risk in Chinese women.

Protein-protein interaction between ezrin and p65 in human breast cancer cells.

Our study aimed to investigate the co-localization and protein-protein interactions between ezrin and p65 in human breast cancer cells. Liquid chromatography-mass spectrometry (LCMS) was used to uncover novel protein interactions with ezrin in MDA-MB-231 cells. Endogenous co-immunoprecipitation was used to validate protein-protein interactions between ezrin and p65 in MDA-MB-231. Exogenous interactions between ezrin and p65 were validated in MDA-MB-231 cells via Flag-ezrin and HA-p65 co-transfection and followed by co-immunoprecipitation. Immunofluorescence staining was used to visualize ezrin and p65 co-localization in MDA-MB-231. LCMS results showed that there were 1000 proteins interacting with ezrin in MDA-MB-231 cells. Ezrin and p65 interactions were confirmed with both endogenous and exogenous methods. We were also able to visualize ezrin and p65 co-localization in MDA-MB-231. In summary, we found protein-protein interactions between Ezrin and p65 in human breast cancer cells.

Effect of different aerodynamic time trial cycling positions on muscle activation and crank torque.

To reduce air resistance, time trial cyclists and triathletes lower their torso angle. The aim of this study was to investigate the effect of lowering time trial torso angle positions on muscle activation patterns and crank torque coordination. It was hypothesized that small torso angles yield a forward shift of the muscle activation timing and crank torque. Twenty-one trained cyclists performed three exercise bouts at 70% maximal aerobic power in a time trial position at three different torso angles (0°, 8°, and 16°) at a fixed cadence of 85 rpm. Measurements included surface electromyography, crank torques and gas exchange. A significant increase in crank torque range and forward shift in peak torque timing was found at smaller torso angles. This relates closely with the later onset and duration of the muscle activation found in the gluteus maximus muscle. Torso angle effects were only observed in proximal monoarticular muscles. Moreover, all measured physiological variables (oxygen consumption, breathing frequency, minute ventilation) were significantly increased with lowering torso angle and hence decreased the gross efficiency. The findings provide support for the notion that at a cycling intensity of 70% maximal aerobic power, the aerodynamic gains outweigh the physiological/biomechanical disadvantages in trained cyclists.

Five-fold symmetry as indicator of dynamic arrest in metallic glass-forming liquids.

With sufficient high cooling rates, a variety of liquids, including metallic melts, will cross a glass transition temperature and solidify into glass accompanying a marked increase of the shear viscosity in approximately 17 orders of magnitude. Because of the intricate atomic structure and dynamic behaviours of liquid, it is yet difficult to capture the underlying structural mechanism responsible for the marked slowing down during glass transition, which impedes deep understanding of the formation and nature of glasses. Here, we report that a universal structural indicator, the average degree of five-fold local symmetry, can well describe the slowdown dynamics during glass transition. A straightforward relationship between structural parameter and viscosity (or α-relaxation time) is introduced to connect the dynamic arrest and the underlying structural evolution. This finding would be helpful in understanding the long-standing challenges of glass transition mechanism in the structural perspective.

The effect of time trial cycling position on physiological and aerodynamic variables.

To reduce aerodynamic resistance cyclists lower their torso angle, concurrently reducing Peak Power Output (PPO). However, realistic torso angle changes in the range used by time trial cyclists have not yet been examined. Therefore the aim of this study was to investigate the effect of torso angle on physiological parameters and frontal area in different commonly used time trial positions. Nineteen well-trained male cyclists performed incremental tests on a cycle ergometer at five different torso angles: their preferred torso angle and at 0, 8, 16 and 24°. Oxygen uptake, carbon dioxide expiration, minute ventilation, gross efficiency, PPO, heart rate, cadence and frontal area were recorded. The frontal area provides an estimate of the aerodynamic drag. Overall, results showed that lower torso angles attenuated performance. Maximal values of all variables, attained in the incremental test, decreased with lower torso angles (P < 0.001). The 0° torso angle position significantly affected the metabolic and physiological variables compared to all other investigated positions. At constant submaximal intensities of 60, 70 and 80% PPO, all variables significantly increased with increasing intensity (P < 0.0001) and decreasing torso angle (P < 0.005). This study shows that for trained cyclists there should be a trade-off between the aerodynamic drag and physiological functioning.

Association analysis of colorectal cancer susceptibility variants with gastric cancer in a Chinese Han population.

Evidence suggests that some genetic variants are risk factors for both colorectal cancer (CRC) and gastric cancer (GC). Thus, we selected 12 reported single nucleotide polymorphisms (SNPs) from genome-wide association studies of CRC and conducted this case-control study to assess the associations between these SNPs and the risk for GC in a southern Chinese population. All SNPs were genotyped in 249 individuals with GC and 292 healthy population-matched subjects using the Sequenom MassArray iPLEX System. Association analyses based on the c2 test and binary logistic regression were performed to determine the odds ratio (OR) and 95% confidence interval (95%CI) for each SNP. A stratified analysis by gender was also performed. Borderline significant associations were observed for rs4444235 (P = 0.070) and rs10411210 (P = 0.084), both fitting the overdominant model. The rs4444235 CT genotype showed a protective effect (OR = 0.72, 95%CI = 0.50-1.03), while the rs10411210 CT genotype was a risk factor (OR = 1.40, 95%CI = 0.96-2.05) as compared with the CC+TT genotype. In the female subgroup, the rs6983267 GT genotype (compared with TT, OR = 2.31, 95%CI = 1.07-4.99) and the rs10505477 CT genotype (compared with TT, OR = 2.36, 95%CI = 1.09-5.11) significantly increased the risk for GC. No significant association was detected for the other SNPs. These results provide evidence that known genetic variants associated with CRC risk may also confer risk for GC.

Homology-based cloning and expression analysis of Rf genes encoding PPR-containing proteins in tobacco.

As a model plant, mechanisms of the cytoplasmic male sterility/restoration of fertility (CMS/Rf) system in tobacco are seldom studied. Using Rf gene sequences from other Solanaceae plants and the draft genome of Nicotiana benthamiana, degenerate primers were designed to amplify the cDNA pool of N. tomentosiformis. In total, six possible Rf sequences were identified, two of which contained base-deletion mutations. The other four were intact open reading frames, of which NtomPPR5 harbored a 3-pentatricopeptide repeat (PPR) motif deletion. Structure analysis revealed that they all encoded a PPR-containing protein with putative mitochondrial targeting signals at their N-terminus, and they all belong to the P subfamily. Phylogenetic analysis showed that all of the Rf-coding PPRs clustered together, and recent duplication events might have occurred in tobacco after the divergence of the species. Quantitative reverse transcription polymerase chain reaction analysis demonstrated that the NtomRfs were expressed in all tissues of N. tomentosiformis and (CMS) K326, although the expression levels varied with gene, organ, and developmental stage. Furthermore, the expression levels of Rf sequences in K326 were lower than those in CMS K326. The molecular basis of the CMS/Rf system in tobacco requires further investigation.

Optimal cycling time trial position models: aerodynamics versus power output and metabolic energy.

The aerodynamic drag of a cyclist in time trial (TT) position is strongly influenced by the torso angle. While decreasing the torso angle reduces the drag, it limits the physiological functioning of the cyclist. Therefore the aims of this study were to predict the optimal TT cycling position as function of the cycling speed and to determine at which speed the aerodynamic power losses start to dominate. Two models were developed to determine the optimal torso angle: a 'Metabolic Energy Model' and a 'Power Output Model'. The Metabolic Energy Model minimised the required cycling energy expenditure, while the Power Output Model maximised the cyclists׳ power output. The input parameters were experimentally collected from 19 TT cyclists at different torso angle positions (0-24°). The results showed that for both models, the optimal torso angle depends strongly on the cycling speed, with decreasing torso angles at increasing speeds. The aerodynamic losses outweigh the power losses at cycling speeds above 46km/h. However, a fully horizontal torso is not optimal. For speeds below 30km/h, it is beneficial to ride in a more upright TT position. The two model outputs were not completely similar, due to the different model approaches. The Metabolic Energy Model could be applied for endurance events, while the Power Output Model is more suitable in sprinting or in variable conditions (wind, undulating course, etc.). It is suggested that despite some limitations, the models give valuable information about improving the cycling performance by optimising the TT cycling position.

The effect of Q factor on gross mechanical efficiency and muscular activation in cycling.

Unexplored in scientific literature, Q Factor describes the horizontal width between bicycle pedals and determines where the foot is laterally positioned throughout the pedal stroke. The aim of the study was to determine whether changing Q Factor has a beneficial effect upon cycling efficiency and muscular activation. A total of 24 trained cyclists (11 men, 13 women; VO2max 57.5 ml·kg/min ± 6.1) pedaled at 60% of peak power output for 5 min at 90 rpm using Q Factors of 90, 120, 150, and 180 mm. Power output and gas were collected and muscular activity of the gastrocnemius medialis (GM), tibialis anterior (TA), vastus medialis (VM), and vastus lateralis (VL) measured using surface electromyography. There was a significant increase (P < 0.006) in gross mechanical efficiency (GME) for 90 and 120 mm (both 19.38%) compared with 150 and 180 mm (19.09% and 19.05%), representing an increase in external mechanical work performed of approximately 4-5 W (1.5-2.0%) at submaximal power outputs. There was no significant difference in the level of activity or timing of activation of the GM, TA, VM, and VL between Q Factors. Other muscles used in cycling, and possibly an improved application of force during the pedal stroke may play a role in the observed increase in GME with narrower Q Factors.