A study of temperature variability on admissions and deaths for cardiovascular diseases in Northwestern China

OBJECTIVE

To explore the effect of temperature variability (TV) on admissions and deaths for cardiovascular diseases (CVDs).

METHOD

The admissions data of CVDs were collected in 4 general hospitals in Jinchang City, Gansu Province from 2013 to 2016. The monitoring data of death for CVDs from 2013 to 2017 were collected through the Jinchang City Center for Disease Control and Prevention. Distributed lag nonlinear model (DLNM) was combined to analyze the effects of TV (daily temperature variability (DTV) and hourly temperature variability (HTV)) on the admissions and deaths for CVDs after adjusting confounding effects. Stratified analysis was conducted by age and gender. Then the attribution risk of TV was evaluated.

RESULTS

There was a broadly linear correlation between TV and the admissions and deaths for CVDs, but only the association between TV and outpatient and emergency room (O&ER) visits for CVDs have statistically significant. DTV and HTV have similar lag effect. Every 1 ℃ increase in DTV and HTV was associated with a 3.61% (95% CI: 1.19% ~ 6.08%), 3.03% (95% CI: 0.27% ~ 5.86%) increase in O&ER visits for CVDs, respectively. There were 22.75% and 14.15% O&ER visits for CVDs can attribute to DTV and HTV exposure during 2013-2016. Males and the elderly may be more sensitive to the changes of TV. Greater effect of TV was observed in non-heating season than in heating season.

CONCLUSION

TV was an independent risk factor for the increase of O&ER visits for CVDs, suggesting effective guidance such as strengthening the timely prevention for vulnerable groups before or after exposure, which has important implications for risk management of CVDs.

A novel protein elicitor (PeSy1) from Saccharothrix yanglingensis induces plant resistance and interacts with a receptor-like cytoplasmic kinase in Nicotiana benthamiana

Previously, we reported a rare actinomycete Saccharothrix yanglingensis Hhs.015 with strong biocontrol ability, which can colonize plant tissues and induce resistance, but the key elicitor and immune mechanisms were unclear. In this study, a novel protein elicitor screened from the genome of Hhs.015, PeSy1 (protein elicitor of S. yanglingensis 1), could induce a strong hypersensitive response (HR) and resistance in plants. The PeSy1 gene encodes an 11 kDa protein with 109 amino acids that is conserved in Saccharothrix species. PeSy1-His recombinant protein induced early defence events such as a cellular reactive oxygen species burst, callose deposition, and the activation of defence hormone signalling pathways, which enhanced Nicotiana benthamiana resistance to Sclerotinia sclerotiorum and Phytophthora capsici, and Solanum lycopersicum resistance to Pseudomonas syringae pv. tomato DC3000. Through pull-down and mass spectrometry, candidate proteins that interacted with PeSy1 were obtained from N. benthamiana. We confirmed the interaction between receptor-like cytoplasmic kinase RSy1 (Response to PeSy1) and PeSy1 using co-immunoprecipitation, bimolecular fluorescence complementation, and microscale thermophoresis. PeSy1 treatment promoted up-regulation of marker genes in pattern-triggered immunity. The cell death it elicited was dependent on the co-receptors NbBAK1 and NbSOBIR1, suggesting that PeSy1 acts as a microbe-associated molecular pattern from Hhs.015. Additionally, RSy1 positively regulated PeSy1-induced plants resistant to S. sclerotiorum. In conclusion, our results demonstrated a novel receptor-like cytoplasmic kinase in the plant perception of microbe-associated molecular patterns, and the potential of PeSy1 in induced resistance provided a new strategy for biological control of actinomycetes in agricultural diseases.

Prevalence of chronic kidney disease in a city of Northwestern China: a cross-sectional study

AIM

Chronic kidney disease (CKD) is increasingly recognized as a global health issue. There is a paucity of published data on the prevalence and risk factors of CKD in less-developed regions. This study aims to evaluate and update the prevalence and risk factors of CKD in a city of Northwestern China.

METHODS

Based on a prospective cohort study, a cross-sectional baseline survey was conducted between 2011 and 2013. The data on the epidemiology interview, physical examination, and clinical laboratory test were all collected. In this study, 41,222 participants were selected from 48,001 workers in the baseline after excluding objects with incomplete information. The crude and standardized prevalence of CKD were calculated. An unconditional logistic regression model was used to analyze the risk factors associated with CKD among male and female.

RESULTS

One thousand seven hundred eighty-eight people were diagnosed with CKD, including 1180 males and 608 females. The crude prevalence of CKD was 4.34% (4.78% males and 3.68% females). The standardized prevalence was 4.06% (4.51% males and 3.60% females). The prevalence of CKD increased with age and was higher in males than in females. In multivariable logistic regression, CKD was significantly associated with the increasing age, drinking, never or occasionally exercise, overweight or obesity, being unmarried, diabetes, hyperuricemia, dyslipidemia and hypertension.

CONCLUSION

In this study, the prevalence of CKD was lower than that of the national cross-sectional study. Lifestyle, hypertension, diabetes, hyperuricemia and dyslipidemia were the main risk factors of CKD. The prevalence and risk factors differ between male and female.

Cohort Profile Update: the China Metal-Exposed workers Cohort Study (Jinchang Cohort)

The Jinchang Cohort was an ongoing 20-year ambispective cohort with unique metal exposures to an occupational population. From January 2014 to December 2019, the Jinchang Cohort has completed three phases of follow-up. The baseline cohort was completed from June 2011 to December 2013, and a total of 48 001 people were included. Three phases of follow-ups included 46 713, 41 888, and 40 530 participants, respectively. The death data were collected from 2001 to 2020. The epidemiological, physical examination, physiological, and biochemical data of the cohort were collected at baseline and during follow-up. Biological specimens were collected on the baseline to establish a biological specimen bank. The concentrations of metals in urine and serum were detected by inductively coupled plasma mass spectrometry (ICP-MS). The new areas of research aim to study the all-cases mortality, the burden of diseases, heavy metals and diseases, and the course of the chain from disease to high-risk outcomes using a combination of macro and micro means, which provided a scientific basis to explore the pathogenesis of multi-etiology and multi-disease and to evaluate the effects of the intervention measures in the population.

Microbial diversity composition of apple tree roots and resistance of apple Valsa canker with different grafting rootstock types

Background

The composition and diversity of root microbial community are affected by plant genotypes and soil environment, which in turn affect plant growth and development. Grafting rootstock types of the apple tree can affect phenotypes in cultivation practice, but it is not clear whether grafting rootstock types can affect the composition and diversity of root microbial community and the resistance of apple tree to apple Valsa canker.

Methods

To explore root microbial differences and the correlation, 16S rRNA and ITS genes were sequenced using Novaseq technology.

Results

The results showed that the influence of grafting rootstock types on the composition of the root fungal community was greater than that of bacteria. And the bacterial community richness was higher in the healthy (OTUs: 1693) and dwarfing rootstock (OTUs: 1526) than in the disease (OTUs: 1181) and standard rootstock (OTUs: 1412), while the fungal community richness was the opposite. Moreover, the bacterial abundance of root zone, rhizosphere, and root endophytic microorganisms with the same grafting rootstock type exhibited a decreasing trend. Results of Nested PCR assay on soil and root tissue of Valsa mali showed that the content of V. mali in dwarfing rootstocks are lower than standard rootstocks. These results suggest that apple trees grafting with dwarfing rootstocks are more resistant to V. mali than standard rootstocks.

Conclusions

Under different grafting types, the effect on the composition of fungal community in apple tree root was greater than that of bacteria. The bacterial community in dwarfing rootstocks is more abundant and diverse, including more beneficial microorganisms. Therefore, dwarfing rootstock is more conducive to the resistance to apple Valsa canker from biological control.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-022-02517-x.

Analysis of droplet size uniformity and selection of spray parameters based on the biological optimum particle size theory

Based on the theory of biological optimal particle size, the most easily attached droplets for different organisms have different particle sizes. To achieve the best average particle size, the droplet size in the atomization field must be more uniform and attain a high the adhesion rate. Therefore, during the application process, not only the average particle size of the droplets but also the influence of the uniformity of the droplets in the spray field must be considered. In this study, 20 small-angle fan nozzles ranging from 20° to 40° are used as the research objects. The droplet size information in the atomization field is obtained using a laser particle size analyzer, and the droplet uniformity under different parameters is calculated. The results showed that within the range of the parameters selected in the experiment, the droplet size increased with an increase in the flow rate, and decreased with an increase in the pressure. In addition, the angle had little effect on the droplet size. Increasing the spray height, spray angle, and pressure, while reducing the equivalent outlet diameter of the nozzle was beneficial to improve the uniformity of droplets. The order of the degree of influence of the four parameters on the uniformity of the droplets was height > equivalent outlet diameter (r) > pressure > spray angle, and the influence weights were 51.1%, 37.1%, 7.8%, 4.1%; 48.4%, 37.6%, 10%, and 4%. Under the condition of the parameter settings used in this experiment, the optimal atomization effect for the four intervals of 150-200 μm, 200-250 μm, 250-300 μm, and 300-400 μm was analyzed from the perspective of uniformity. The nozzle models with the best atomization effects in each interval were SS4003-0.3 MPa, SS4006-0.3 MPa, SS4008-0.3 MPa, and 633.512.30.CC-0.1 MPa.

Construction of a theoretical model for fan nozzles with precise atomization angles for plant protection

The fan nozzle is widely used in the process of pest control in agriculture and forestry. The spray angle of the nozzle is an important characterization parameter in the atomization of liquids. The spray angle of the nozzle is an important characterizing parameter in the liquid atomization process. It affects the flow field at the exit of the nozzle, thereby affecting the size and velocity of the droplets, and further affecting the deposition effect of the droplets on the crop. Therefore, its research is of great significance for improving the deposition of liquid on plants and controlling pests and related diseases. Based on the classical theory of predecessors and considering the parameters of the flat fan nozzle, we further optimized the theory at the structural level by means of a simulation test and built a spray angle theoretical model taking into account the parameters of the inner chamber of the nozzle. We arrived at the following conclusions: (1) the average error of the spray angle measured by the simulation test and the actual test spray angle was 2.95%, the maximum spray angle deviation value was 2.81°, and the result proves that the simulation test parameter setting is accurate; and (2) the average error between the actual measured value and the theoretical model calculation value was 3.56%, the maximum spray angle deviation was 4°, through the actual test comparison, and the spray angle error of the theoretical model was within the allowable error range of industry production. It was proved that the model could effectively reflect the changing law of spray angle of the flat fan nozzle.

The effect and prediction of diurnal temperature range in high altitude area on outpatient and emergency room admissions for cardiovascular diseases

PURPOSE

Diurnal temperature range (DTR) is a meteorological indicator closely associated with global climate change. Thus, we aim to explore the effects of DTR on the outpatient and emergency room (O&ER) admissions for cardiovascular diseases (CVDs), and related predictive research.

METHODS

The O&ER admissions data for CVDs from three general hospitals in Jinchang of Gansu Province were collected from 2013 to 2016. A generalized additive model (GAM) with Poisson regression was employed to analyze the effect of DTR on the O&ER admissions for all cardiovascular diseases, hypertension, ischemic heart disease (IHD) and stoke. GAM was also used to preform predictive research of the effect of DTR on the O&ER admissions for CVDs.

RESULTS

There were similar positive linear relationships between DTR and the O&ER visits with the four cardiovascular diseases. And the cumulative lag effects were higher than the single lag effects. A 1 °C increase in DTR corresponded to a 1.30% (0.99-1.62%) increase in O&ER admissions for all cardiovascular diseases. Males and elderly were more sensitivity to DTR. The estimates in non-heating season were higher than in heating season. The trial prediction accuracy rate of CVDs based on DTR was between 59.32 and 74.40%.

CONCLUSIONS

DTR has significantly positive association with O&ER admissions for CVDs, which can be used as a prediction index of the admissions of O&ER with CVDs.

An effect of 24-hour temperature change on outpatient and emergency and inpatient visits for cardiovascular diseases in northwest China

Some studies suggested that 24-h temperature change (TC24) was one of the potential risk factors for human health. However, evidence of the short-term effect of TC24 on outpatient and emergency department (O&ED) visits and hospitalizations for cause-specific cardiovascular diseases (CVDs) is still limited. The aim of this study is to explore the short-term effects of TC24 on O&ED visits and hospitalizations for CVDs in northwest China which is an area with large temperature variation. The O&ED visits records for CVDs of 3 general hospitals and the inpatient records for CVDs of 4 general hospitals were collected from January 1, 2013, to December 31, 2016, in Jinchang City, northwest China. Meteorological and air pollution data were also obtained during the same study period from local meteorological monitoring station and environmental monitoring station, respectively. A generalized additive model (GAM) with Poisson regression was employed to analyze the effects of TC24 on O&ED visits and hospitalizations for CVDs. V-shaped relationship were found between TC24 and O&ED visits and hospitalizations for CVDs, including total CVD, hypertension, coronary heart disease (CHD) and stroke. Stratified analysis showed that men and patients over 65 years old were more susceptible to temperature changes. The estimates in non-heating months were higher than in full year. TC24 can affect the O&ED visits and hospitalizations for CVDs in this study. This study provides useful data for policy makers to better prepare local responses to the impact of changes in temperature on population health.

Effects of Outdoor Temperature on Blood Pressure in a Prospective Cohort of Northwest China

OBJECTIVE

The relationship between outdoor temperature and blood pressure (BP) has been inconclusive. We analyzed data from a prospective cohort study in northwestern China to investigate the effect of outdoor temperature on BP and effect modification by season.

METHODS

A total of 32,710 individuals who participated in both the baseline survey and the first follow-up in 2011-2015 were included in the study. A linear mixed-effect model and generalized additive mixed model (GAMM) were applied to estimate the association between outdoor temperature and BP after adjusting for confounding variables.

RESULTS

The mean differences in systolic blood pressure (SBP) and diastolic blood pressure (DBP) between summer and winter were 3.5 mmHg and 2.75 mmHg, respectively. After adjusting for individual characteristics, meteorological factors and air pollutants, a significant increase in SBP and DBP was observed for lag 06 day and lag 04 day, a 0.28 mmHg (95% CI: 0.27-0.30) per 1 °C decrease in average temperature for SBP and a 0.16 mmHg (95% CI: 0.15-0.17) per 1 °C decrease in average temperature for DBP, respectively. The effects of the average temperature on both SBP and DBP were stronger in summer than in other seasons. The effects of the average temperature on BP were also greater if individuals were older, male, overweight or obese, a smoker or drinker, or had cardiovascular diseases (CVDs), hypertension, and diabetes.

CONCLUSIONS

This study demonstrated a significant negative association between outdoor temperature and BP in a high-altitude environment of northwest China. Moreover, BP showed a significant seasonal variation. The association between BP and temperature differed by season and individuals' demographic characteristics (age, gender, BMI), unhealthy behaviors (smoking and alcohol consumption), and chronic disease status (CVDs, hypertension, and diabetes).

Scutellarin Reduce the Homocysteine Level and Alleviate Liver Injury in Type 2 Diabetes Model

Scutellarin (SCU) is an active ingredient extracted from Erigeron breviscapus (Vaniot) Hand.-Mazz. Its main physiological functions are anti-inflammatory and antioxidant. In this study, we established a STZ-induced model of type 2 diabetes (T2DM) and a homocysteine (Hcy)-induced apoptosis model of LO2 to investigate whether SCU can alleviate liver damage by regulating Hcy in type 2 diabetes. Biochemical analysis indicated that SCU could improve the lipid metabolism disorder and liver function in diabetic rats by downregulating the levels of triglycerides (TG), cholesterol (CHO), low-density lipoprotein (LDL), alanine transaminase (ALT) and aspartate transaminase (AST), and by upregulating the level of high-density lipoprotein (HDL). Interestingly, SCU also could down-regulate the levels of Hcy and insulin and enhance the ability of type 2 diabetic rats to regulate blood glucose. Mechanistically, our results indicated that SCU may control the level of Hcy through regulating the levels of β-Cystathionase (CBS), γ-Cystathionase (CSE) and 5,10-methylenetetrahydrofolate (MTHFR) in liver tissue, and up-regulate folic acid, VitB₆ and VitB₁₂ levels in serum. Furthermore, SCU inhibits apoptosis in the liver of T2DM rats and in cultured LO2 cells treated with Hcy. Together, our findings suggest that SCU may alleviate the liver injury thorough downregulating the level of Hcy in T2DM rats.

The effect of diurnal temperature range on blood pressure among 46,609 people in Northwestern China

BACKGROUND

A large number of studies have found a positive association between diurnal temperature range (DTR) and cardiovascular diseases (CVDs) incidence and mortality. Few studies regarding the effects of DTR on blood pressure (BP) are available.

OBJECTIVE

To investigate the effects of DTR on BP in Jinchang, northwestern China.

METHODS

Based on a prospective cohort research, a total of 46,609 baseline survey data were collected from 2011 to 2015. The meteorological observation data and environmental monitoring data were collected in the same period. The generalized additive model (GAM) was used to estimate the relationship between DTR and BP after adjusting for confounding variables.

RESULTS

Our study found that there was a positive linear correlation between DTR and systolic blood pressure (SBP) and plus pressure (PP), and a negative linear correlation between DTR and diastolic blood pressure (DBP). With a 1 °C increase of DTR, SBP and PP increased 0.058 mmHg (95%CI: 0.018-0.097) and 0.114 mmHg (95%CI: 0.059-0.168) respectively, and DBP decreased 0.039 mmHg (95%CI:-0.065 ~ -0.014). There was a significant interaction between season and DTR on SBP and PP. DTR had the greatest impact on SBP and PP in hot season. The association between DTR and BP varied significantly by education level.

CONCLUSION

There was a significant association between DTR and BP in Jinchang, an area with large temperature change at high altitudes in northwestern China. These results provide new evidence that DTR is an independent risk factor for BP changes among general population. Therefore, effective control and management of BP in the face of temperature changes can help prevent CVDs.

HIF-1α Mediates Osteoclast-Induced Mandibular Condyle Growth via AMPK Signaling

During the mandibular condylar growth, the absorption of calcified cartilage matrix induced by osteoclasts is crucial for the continuous endochondral osteogenesis. Meanwhile, recent studies showed that subchondral bone resided within the low-oxygen microenvironment, and our previous study revealed that hypoxia-inducible transcription factor 1α (HIF-1α) promoted osteoclastogenesis under hypoxia. However, whether HIF-1α regulates the function of osteoclasts in the mandibular condyle cartilage remains elusive. Our study indicated that severe deformity of the mandibular condyle was displayed in 10-wk-old osteoclast-specific HIF-1α conditional knockout (CKO) mice, accompanied by shortened length of condylar process and disorganized fibrocartilage. In 1-, 2-, and 4-wk-old CKO mice, the size of the hypertrophic layer and chondrocytic layer was significantly thickened. In the chondrocytic layer, chondrocytes were atrophied, showing a form of apoptosis in 4-wk-old CKO mice. Furthermore, an increase in the thickness of the fibrous and proliferating layer was observed in 10-wk-old CKO mice, as well as a significant decrease in that of the chondrocytic and hypertrophic chondrocyte layers. Interestingly, the articular surface of the condylar process abnormally presented a horizontal concave shape, and a disk-like acellular connective tissue appeared. In addition, genetic ablation of HIF-1α blunted cartilage matrix loss by subchondral osteoclast deficiency, resulting in a high subchondral bone mass phenotype, accompanied with a decreased number of blood vessels, alkaline phosphatase staining, and vascular endothelial growth factor (VEGF) expression. Mechanistically, the number of osteoclasts in the center of the condyle in CKO mice was significantly reduced by attenuated expression of adenosine 5′-monophosphate-activated protein kinase (AMPK) signaling. These findings reveal a novel influence of HIF-1α function in osteoclasts on maintenance of osteoclast-induced resorption of calcified cartilage matrix via AMPK signaling, as well as subchondral bone formation through VEGF-dependent angiogenesis in bone marrow.

Extracting Diameter at Breast Height with a Handheld Mobile LiDAR System in an Outdoor Environment

Mobile laser scanning (MLS) is widely used in the mapping of forest environments. It has become important for extracting the parameters of forest trees using the generated environmental map. In this study, a three-dimensional point cloud map of a forest area was generated by using the Velodyne VLP-16 LiDAR system, so as to extract the diameter at breast height (DBH) of individual trees. The Velodyne VLP-16 LiDAR system and inertial measurement units (IMU) were used to construct a mobile measurement platform for generating 3D point cloud maps for forest areas. The 3D point cloud map in the forest area was processed offline, and the ground point cloud was removed by the random sample consensus (RANSAC) algorithm. The trees in the experimental area were segmented by the European clustering algorithm, and the DBH component of the tree point cloud was extracted and projected onto a 2D plane, fitting the DBH of the trees using the RANSAC algorithm in the plane. A three-dimensional point cloud map of 71 trees was generated in the experimental area, and estimated the DBH. The mean and variance of the absolute error were 0.43 cm and 0.50, respectively. The relative error of the whole was 2.27%, the corresponding variance was 15.09, and the root mean square error (RMSE) was 0.70 cm. The experimental results were good and met the requirements of forestry mapping, and the application value and significance were presented.

Hematopoietic-substrate-1 associated protein X-1 (HAX-1) regulates liver cancer cells growth, metastasis, and angiogenesis through Akt

The aim of this study was to investigate the effects and mechanisms of hematopoietic-substrate-1-associated protein X-1 (HAX-1) on liver cancer cells. Information on HAX-1 from liver cancer patients was analyzed by the Cancer Genome Atlas (TCGA) program. Cell migration and invasion abilities were respectively tested by scratch assay and transwell assay. Tube formation assay was applied to detect angiogenesis protein and mRNA was determined using quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot. We found that the median month survival of HAX-1 overexpressing liver cancer patients was shorter than that of HAX-1 normal liver cancer patients. HAX-1 was overexpressed in liver cancer tissues and cells, and HAX-1 overexpression promoted the liver cancer cells growth, migration, and invasion, whereas silencing HAX-1 produced the opposite results. Inhibition of Akt by LY294002 reversed the migration and invasion abilities of liver cancer cells, and inhibited the ability of cells growth and angiogenesis. Silencing PIK3CA enhanced the inhibitory effects of HAX-1 silencing on the viability, migration, and invasion of liver cancer cells. HAX-1 affected liver cancer cells metastasis and angiogenesis by affecting Akt phosphorylation and FOXO3A expression.

[The clinical significance of PRL-3,VEGF expression in sinonasalsquamous cell carcinoma]

Objective:To analyze the clinical significance of phosphatase of regenerating liver-3(PRL-3) and vascular endothelial growth factor(VEGF)expression in sinonasal squamous cell carcinomas.Method:We use immunohistochemical analysis and RT-PCR to detecte the expression of PRL-3 and VEGF protein in 62 cases of sinonasal squamous carcinoma tissues(SNSCC),30 cases of nasal polyps(NP),and 25 cases of normal nasal mucosa(NM).Result:①The expression of PRL-3 and VEGF in sinonasal squamous cell carcinoma tissues were statistically higher than in nasal polyps and normal nasal mucosa tissues (P<0.05).②The expression of PRL-3 and VEGF were not correlated with patient's age or gender(P>0.05).But the High expression of PRL-3 and VEGF in SNSCC was significantly related with advanced,lower tumor differentiation and lymph node metastasis(P<0.05).③The expression of PRL-3 and VEGF was positively correlated in sinonasal squamous cell carcinomas.Conclusion:The expression of PRL-3 and VEGF in SNSCC may involve in the regulation of tumor growth and differentiation.The expressing intensity may reflect the proliferation activity of sinonasal squamous cell carcinoma cell.PRL-3 and VEGF may promote the tumor metastasis in a synergistic manner.

Strategies of traversing obstacles and the simulation for a forestry chassis

As to the complicated terrain in forest, forestry chassis with an articulated body with three degrees of freedom and installed luffing wheel-legs (FC-3DOF&LW) is a novel chassis that can surmount obstacles. In addition, the rear frame of FC-3DOF&LW is regarded as the platform to carry equipment. Small inclination angle for rear frame contributes to stability and ride comfort. This article describes the strategy of traversing obstacles and simulation for FC-3DOF&LW that drives in forest terrain. First, key structures of FC-3DOF&LW are briefly introduced, which include articulated structure with three degrees of freedom and luffing wheel-leg. Based on the sketch of luffing wheel-leg, the movement range of luffing wheel-leg is obtained by hydraulic cylinder operation. Second, the strategy of crossing obstacles that are simplified three models of terrain is presented, and the simulation for surmounting obstacles is constructed in multibody dynamics software. The simulation results demonstrate that the inclination angle of rear frame is 18° when slope is 30°. A maximum 12° decrease of inclination angle for rear frame can be acquired when luffing wheel-legs are applied. For traversing obstacles with both sides, the maximum inclination angle of rear frame is about 1.2° and is only 3° for traversing obstacles with single side.

Male requires a higher median target effect-site concentration of propofol for I-gel placement when combined with dexmedetomidine

OBJECTIVE

The supraglottic airway device (SAD) can be used for airway management of spontaneous breathing patients, and propofol is commonly applied for the SAD placement. This study was designed to assess the effect of gender on median target effect-site concentration (Ce₅₀) of propofol for I-gel placement when combined with dexmedetomidine.

MATERIAL AND METHOD

19 males and 18 females, aged 18 to 59 and undergoing elective surgery, were enrolled. After intravenous infusion of dexmedetomidine 1.0μg/kg over 10min followed by continuous infusion of 0.4μg/kg/h, target-controlled infusion of propofol under Marsh model was started and the initial Ce of propofol was set at 4.79μg/mL and 4.35μg/mL in the male and female patients, respectively. The I-gel was inserted when the Ce of propofol reached the pre-set concentration and bispectral index value was less than 60. The Ce of propofol required for I-gel placement was determined by the Dixon up-and-down method.

RESULTS

The Ce₅₀ (95% confidence interval) of propofol required for I-gel placement were 4.082μg/mL (3.798-4.332μg/mL) and 3.509μg/mL (3.266-3.749μg/mL) in male and female patients, respectively, with a significantly higher Ce₅₀ in males.

CONCLUSION

When combined with dexmedetomidine, males require a higher Ce₅₀ of propofol for I-gel placement compared to females.

Ischemic or toxic injury: A challenging diagnosis and treatment of drug-induced stenosis of the sigmoid colon

A 48-year-old woman was admitted with 15-mo history of abdominal pain, diarrhea and hematochezia, and 5-mo history of defecation difficulty. She had been successively admitted to nine hospitals, with an initial diagnosis of inflammatory bowel disease with stenotic sigmoid colon. Findings from computed tomography virtual colonoscopy, radiography with meglumine diatrizoate, endoscopic balloon dilatation, metallic stent implantation and later overall colonoscopy, coupled with the newfound knowledge of compound Qingdai pill-taking, led to a subsequent diagnosis of ischemic or toxic bowel disease with sigmoid colon stenosis. The patient was successfully treated by laparoscopic sigmoid colectomy, and postoperative pathological examination revealed ischemic or toxic injury of the sigmoid colon, providing a final diagnosis of drug-induced sigmoid colon stenosis. This case highlights that adequate awareness of drug-induced colon stenosis has a decisive role in avoiding misdiagnosis and mistreatment. The diagnostic and therapeutic experiences learnt from this case suggest that endoscopic balloon expansion and colonic metallic stent implantation as bridge treatments were demonstrated as crucial for the differential diagnosis of benign colonic stenosis. Skillful surgical technique and appropriate perioperative management helped to ensure the safety of our patient in subsequent surgery after long-term use of glucocorticoids.

Xanthotoxin prevents bone loss in ovariectomized mice through the inhibition of RANKL-induced osteoclastogenesis

Xanthotoxin (XAT) is extracted from the seeds of Ammi majus. Here, we reported that XAT has an inhibitory effect on osteoclastogenesis in vitro through the suppression of both receptor activator of nuclear factor-κB ligand (RANKL)-induced ROS generation and Ca(2+) oscillations. In vivo studies showed that XAT treatment decreases the osteoclast number, prevents bone loss, and restores bone strength in ovariectomized mice.

INTRODUCTION

Excessive osteoclast formation and the resultant increase in bone resorption activity are key pathogenic factors of osteoporosis. In the present study, we have investigated the effects of XAT, a natural furanocoumarin, on the RANKL-mediated osteoclastogenesis in vitro and on ovariectomy-mediated bone loss in vivo.

METHODS

Cytotoxicity of XAT was evaluated using bone marrow macrophages (BMMs). Osteoclast differentiation, formation, and fusion were assessed using the tartrate-resistant acid phosphatase (TRAP) stain, the actin cytoskeleton and focal adhesion (FAK) stain, and the fusion assay, respectively. Osteoclastic bone resorption was evaluated using the pit formation assay. Reactive oxygen species (ROS) generation and removal were evaluated using dichlorodihydrofluorescein diacetate (DCFH-DA). Ca(2+) oscillations and their downstream signaling targets were then detected. The ovariectomized (OVX) mouse model was adopted for our in vivo studies.

RESULTS

In vitro assays revealed that XAT inhibited the differentiation, formation, fusion, and bone resorption activity of osteoclasts. The inhibitory effect of XAT on osteoclastogenesis was associated with decreased intracellular ROS generation. XAT treatment also suppressed RANKL-induced Ca(2+) oscillations and the activation of the resultant downstream calcium-CaMKK/PYK2 signaling. Through these two mechanisms, XAT downregulated the key osteoclastogenic factors nuclear factor of activated T cells c1 (NFATc1) and c-FOS. Our in vivo studies showed that XAT treatment decreases the osteoclast number, prevents bone loss, rescues bone microarchitecture, and restores bone strength in OVX mice.

CONCLUSION

Our findings indicate that XAT is protective against ovariectomy-mediated bone loss through the inhibition of RANKL-mediated osteoclastogenesis. Therefore, XAT may be considered to be a new therapeutic candidate for treating osteoporosis.

Dihydroartemisinin attenuates lipopolysaccharide-induced osteoclastogenesis and bone loss via the mitochondria-dependent apoptosis pathway

Dihydroartemisinin (DHA) is a widely used antimalarial drug isolated from the plant Artemisia annua. Recent studies suggested that DHA has antitumor effects utilizing its reactive oxygen species (ROS) yielding mechanism. Here, we reported that DHA is inhibitory on lipopolysaccharide (LPS)-induced osteoclast (OC) differentiation, fusion and bone-resorption activity in vitro. Intracellular ROS detection revealed that DHA could remarkably increase ROS accumulation during LPS-induced osteoclastogenesis. Moreover, cell apoptosis was also increased by DHA treatment. We found that DHA-activated caspase-3 increased Bax/Bcl-2 ratio during LPS-induced osteoclastogenesis. Meanwhile, the translocation of apoptotic inducing factor (AIF) and the release of cytochrome c from the mitochondria into the cytosol were observed, indicating that ROS-mediated mitochondrial dysfunction is crucial in DHA-induced apoptosis during LPS-induced osteoclastogenesis. In vivo study showed that DHA treatment decreased OC number, prevents bone loss, rescues bone microarchitecture and restores bone strength in LPS-induced bone-loss mouse model. Together, our findings indicate that DHA is protective against LPS-induced bone loss through apoptosis induction of osteoclasts via ROS accumulation and the mitochondria-dependent apoptosis pathway. Therefore, DHA may be considered as a new therapeutic candidate for treating inflammatory bone loss.

Application of CT virtual endoscopy in diagnosis of colorectal diseases

Colorectal diseases are a group of common diseases. In recent years, extensive attention has been paid to the application of computed tomography virtual endoscopy (CTVE) in the diagnosis of colorectal diseases. Through the literature search, combined with the author's experience, we explore the technical principle, bowel preparation and inspection method of CTVE, making a summary of the value of CTVE in the diagnosis of colorectal diseases. CTVE can fully observe morphological characteristics of colorectal cancer, polyps, and inflammatory disease. CTVE can not only determine the lesion location, shape, and size, but also confirm the extent of invasion into the colorectal wall, surrounding tissue and distant metastasis. However, the main limitation is that the detected lesion cannot be biopsied or treated during CTVE. Therefore, CTVE is a new, rapid, convenient, safe, non-invasive, and effective method for colorectal examination, which can be used for screening of colorectal diseases.

[Study on extraction process of coumarin in a Mongolian drug Chagan-sorlo (Radix Glehniae)]

The present paper discusses ultrasonic extraction method aided extraction of coumarin from a Mongolian drug, Chagan-sorlo (Radix Glehniae), aiming to study out how much coumarin contained in Chagan-sorlo, and to provide the scientific basis and production guidance for extracting coumarin from Chagan-sorlo. Under different conditions the coumarin in Chagan-sorlo was extracted by ultrasonic, measured and analyzed, and then HPLC was used to carry out the measurement. Result showed that with solvent volume fraction of 70%, extraction time of 20 min, ultrasonic power of 175 W, temperature of 25 degrees C, solid-liquid ratio of 1 : 20, and 80-100 mesh extraction, the coumarin extraction reaches the highest yield.

[Construction of a melon genetic map with fruit and seed QTLs]

A genetic map of melon was constructed using 143 F2 population developed from a cross between two distant lines Ano2 of Japan and Hami melon K413. The map contains 12 linkage groups and 142 markers, including 121 AFLPs, 16 SSRs, 3 STSs, 2 trait markers and covers 1 014.2 cM. Composite interval mapping (CIM) method was used to detect QTLs involved in melon fruit and seed traits: fruit length (FL), fruit width (FW), fruit shape (length/width, FS), centre sugar (CS), edge sugar (ES), flesh texture (FT), seed length (SL), seed width (SW), seed shape (SS), and seed weight (SW). The result showed that Flesh was located between AFLP markers NDAA and NCFA on C9. A total of 25 QTLs were detected for other traits and some QTLs were co-located with each other. The QTLs Sl5.1, Sw5.1, and Swt5.1 located on linkage C5 between NCA and N73C explained a significant portion of associated phenotypic variation (R2=17%, 19%, 23%). The allele from Ano2 obviously suppressed the length, width, and weight of melon seed; the QTLs between N73A and NFDA on C8 were involved in seed width, shape, and weight; the QTL Fs8.1 on C8 was detected using both F2 and F3 fruit data and explained a significant portion of phenotypic variation 25% and 19%. Fs8.1 showed partly dominant, and the allele from Ano2 sup-pressed elongation of fruit to form round melon. The QTLs related to centre sugar, edge sugar, and fruit texture were also detected in this research.

Nuclear transfer procedures in the ovine can induce early embryo fragmentation and compromise cloned embryo development

Cytoplasmic fragmentations are frequently observed in early mammalian embryos, and especially in the human. In our research we have observed subtle clues that the occurrence of fragmentation was most likely a result of somatic cell nuclear transfer (NT) protocols, and in particular, the in vitro culture system. In this study we examined various putative factors that might induce early embryo fragmentation in the ovine. The results indicate that nuclear transfer protocols such as the fusion parameter, activation treatment, and especially the choice of culture medium affected embryo cleavage rates and resulted in a higher incidence of fragmented embryos. Upon using the same fusion parameter, activation parameters that were based upon amino acids containing synthetic oviduct fluids (SOFaa) culture system resulted in significantly lower fragmentation rates than when utilizing a Charles Rosenkrans 1 (CR1aa) culture system. Fragmented embryos typically exhibited irregular numbers of blastomeres with the majority of blastomeres devoid of chromatin. Factors such as fusion DC pulse, activation treatment and culture system led to higher fragmentation and also affected in vitro and in vivo embryo development. The SOFaa based culture system produced a higher number of quality NT embryos resulting in higher pregnancy rates and the birth of live lambs as compared to the CR1aa based system (P<0.05). We conclude that early embryo fragmentation in the ovine is caused by suboptimal cloning protocols, and NT embryo development is especially affected by the culture system used.

Nephrotoxicity of mercuric chloride, methylmercury and cinnabar-containing Zhu-Sha-An-Shen-Wan in rats

Cinnabar (HgS) is used in traditional medicines, and total Hg content is used for risk assessment of cinnabar-containing traditional medicines such as Zhu-Sha-An-Shen-Wan (ZSASW). Is ZSASW or cinnabar toxicologically similar to common mercurials? Adult Sprague-Dawley rats were gavaged with ZSASW (1.4 g/kg), cinnabar (0.2g/kg), HgCl(2) (0.02 g/kg), MeHg (0.001 g/kg), or saline daily for 60 days, and toxicity was determined. Animal body-weight gain was decreased by HgCl(2) and MeHg. Blood urea nitrogen (BUN) was increased by MeHg. Histology showed severe kidney injury following MeHg and HgCl(2) treatments, but mild after ZSASW and cinnabar. Renal Hg contents were markedly increased in the HgCl(2) and MeHg groups but were not elevated in the ZSASW and cinnabar groups. The expression of kidney injury molecule-1 was increased 50-fold by MeHg, 4-fold by HgCl(2), but was unaltered by ZSASW and cinnabar; the expression of matrilysin was increased 3-fold by MeHg. In contrast, the expression of N-cadherin was decreased by HgCl(2). Thus, ZSASW and cinnabar are much less nephrotoxic than HgCl(2) and MeHg, indicating that chemical forms of mercury underlie their disposition and toxicity.

[Diagnostic value of 128-slice CT coronary angiography in comparison with invasive coronary angiography]

OBJECTIVE

To observe the diagnostic value of non-invasive 128-slice computed tomography coronary angiography (CTA) in comparison with invasive coronary angiography.

METHODS

128-slice CTA and invasive coronary angiography were performed in 78 unselected consecutive patients (63 patients with suspected coronary artery disease and 15 patients with previous coronary stenting, 56 males, mean age 61 +/- 10 years) and > 50% reduction of minimal lumen diameter was defined as significant coronary stenosis.

RESULTS

Fifty-eight out of 879 segments (7%) from CTA were not assessable because of irregular rhythm, vessel calcification or tachycardia. Compared with invasive coronary angiography, segment-based analysis from the 821 segments showed the sensitivity by CTA was 87%, specificity 97%, PPV 83% and NPV 97%. Four out of 22 stents implanted in 15 patients were not assessable by CTA because of poor image quality. Compared with invasive coronary angiography, the sensitivity of diagnosing in-stent restenosis by CTA was 100%, specificity 77%, PPV 63% and NPV 100% for the remaining 18 stents.

CONCLUSIONS

One hundred and twenty-eight-slice CTA has a high accuracy for detecting coronary artery disease and in-stent restenosis after coronary stenting and could be considered as a valuable noninvasive technique for screening coronary artery disease in suspected patients.

Effect of additives on the release of a model protein from PLGA microspheres

The purpose of this study was to investigate the effect of 2 additives, poly(ethylene glycol) (PEG) 1000 and 1,2,3-tridecanoyl glycerol (tricaprin), on the physico-chemical characteristics and in vitro release of a model protein, bovine serum albumin (BSA), form poly(D,L-lactic-co-glycolic acid) (PLGA) microspheres. BSA-loaded microspheres were prepared by the double emulsion solvent evaporation method. Additives were incorporated into microspheres to modify the release of protein. The addition of PEG 1000 and tricaprin changed the surface characteristics of microspheres from smooth and nonporous to porous and dimpled, respectively. The in vitro release profiles showed that the additives significantly (P < 0.05) increased the early-stage release of BSA from microspheres.

Mercurial sensitivity of aquaporin 1 endofacial loop B residues

The water channel protein aquaporin-1 (AQP1) has two asparagine-proline-alanine (NPA) repeats on loops B and E. From recent structural information, these loops are on opposite sides of the membrane and meet to form a pore. We replaced the mercury-sensitive residue cysteine 189 in AQP1 by serine to obtain a mercury-insensitive template (C189S). Subsequently, we substituted three consecutive cysteines for residues 71-73 near the first NPA repeat (76-78) in intracellular loop B, and investigated whether they were accessible to extracellular mercurials. AQP1 and its mutants were expressed in Xenopus laevis oocytes, and the osmotic permeability (P(f)) of the oocytes was determined. C189S had wild-type P(f) but was not sensitive to HgCl(2). Expression of all three C189S cysteine mutants resulted in increased P(f), and all three mutants regained mercurial sensitivity. These results, especially the inhibitions by the large mercurial p-chloromercunbenzene-sulfonic acid (pCMBS) ( approximately 6A wide), suggest that residues 71-73 at the pore are accessible to extracellular mercurials. A 30-ps molecular dynamics simulation (at 300 K) starting with crystallographic coordinates of AQP1 showed that the width of the pore bottleneck (between Connolly surfaces) can vary (w(avg) = 3.9 A, sigma = 0.75; hydrated AQP1). Thus, although the pore width would be > or = 6 A only for 0.0026 of the time, this might suffice for pCMBS to reach residues 71-73. Alternative explanations such as passage of pCMBS across the AQP1 tetramer center or other unspecified transmembrane pathways cannot be excluded.

[The protective effect of ligustrazine on optic nerve axons in rabbit eyes with continuous elevated IOP]

OBJECTIVE

To investigate the effects of ligustrazine on optic nerve axons in rabbit eyes with continuous elevated intraocular pressure (IOP).

METHOD

Thirty-six NZ rabbits with continuous elevated IOP induced by injection of alpha-chymotrypsin into anterior chamber were divided into two groups by randomization: treatment and control group. Ten mg/kg ligustrazine injected into the treatment group every day for 3 weeks began on the 7(th) day after IOP elevated continuously. The changes of conjunctival microcirculation and optic nerve axonal ultrastructure were observed at different time points.

RESULTS

The destruction of conjunctival microcirculation and axonal ultrastructure was milder in treatment group than that in the control group. In addition, the total number of axons and the percentage of axons in optic nerve area were higher, whereas the axonal diameter was smaller in the treatment group.

CONCLUSION

It is suggested that ligustrazine protect optic nerve axons from more damage induced by elevated IOP through improving ocular microcirculation.

[Cultured bovine corneal epithelial cells express functional water channel]

OBJECTIVE

To investigate the water permeability (P(f)) of the cultured bovine corneal epithelial cells (CBCEC) and whether aquaporins (AQPs) were present.

METHODS

Laser light-scattering system was used to determine the volume change of CBCEC from isotonic status rapidly transferred to hypotonic one, and the P(f) value was calculated. Messenger RNA obtained from CBCEC was injected into Xenopus laevis oocytes. After four days, the P(f) was determined by monitoring volume changes of oocytes upon hypoosmotic challenge (180 mOsm/L changed to 15 mOsm/L).

RESULTS

CBCEC challenged with 10% hypoosmotic solution at 37 degrees C swelled rapidly; the cellular P(f) was 72 microm/s. In the oocytes injected with mRNA from CBCEC, the P(f) increased to 76 microm/s. This increase was inhibited (by 89%) by 0.3 mmol/L HgCl(2).

CONCLUSION

Our results suggest that CBCEC express a typical mercurial-sensitive functional water channel in good numbers, judging from the comparatively high P(f) we measured. These begin to reopen the question of the presence and extent of an epithelial role in control of corneal hydration.

Profilin promotes barbed-end actin filament assembly without lowering the critical concentration

The mechanism of profilin-promoted actin polymerization has been systematically reinvestigated. Rates of barbed-end elongation onto Spectrin.4.1. Actin seeds were measured by right angle light scattering to avoid confounding effects of pyrenyl-actin, and KINSIM was used to analyze elongation progress curves. Without thymosin-beta4, both actin and Profilin. Actin (P.A) are competent in barbed-end polymerization, and kinetic simulations yielded the same bimolecular rate constant ( approximately 10 x 10(6) M(-1) s(-1)) for actin monomer or Profilin. Actin. When measured in the absence of profilin, actin assembly curves over a 0.7-4 microM thymosin-beta4 concentration range fit a simple monomer sequestering model (1 microM K(D) for Thymosin-beta4. Actin). The corresponding constant for thymosin-beta4.pyrenyl-Actin, however, was significantly higher ( approximately 9-10 microM), suggesting that the fluorophore markedly weakens binding to thymosin-beta4. With solutions of actin (2 microM) and thymosin-beta4 (2 or 4 microM), the barbed-end assembly rate rose with increasing profilin concentration (0.7-2 microM). Actin assembly in presence of thymosin-beta4 and profilin fit a simple thermodynamic energy cycle, thereby disproving an earlier claim (D. Pantaloni and M.-F. Carlier (1993) Cell 75, 1007-1014) that profilin promotes nonequilibrium filament assembly by accelerating hydrolysis of filament-bound ATP. Our findings indicate that profilin serves as a polymerization catalyst that captures actin monomers from Thymosin-beta4. Actin and ushers actin as a Profilin. Actin complex onto growing barbed filament ends.

Transport of fluid by lens epithelium

We report for the first time that cultured lens epithelial cell layers and rabbit lenses in vitro transport fluid. Layers of the alphaTN4 mouse cell line and bovine cell cultures were grown to confluence on permeable membrane inserts. Fluid movement across cultured layers and excised rabbit lenses was determined by volume clamp (37 degrees C). Cultured layers transported fluid from their basal to their apical sides against a pressure head of 3 cmH2O. Rates were (in microliter. h-1. cm-2) 3.3 +/- 0.3 for alphaTN4 cells (n = 27) and 4.7 +/- 1.0 for bovine layers (n = 6). Quinidine, a blocker of K+ channels, and p-chloromercuribenzenesulfonate and HgCl2, inhibitors of aquaporins, inhibited fluid transport. Rabbit lenses transported fluid from their anterior to their posterior sides against a 2.5-cmH2O pressure head at 10.3 +/- 0.62 microliter. h-1. lens-1 (n = 5) and along the same pressure head at 12.5 +/- 1.1 microliter. h-1. lens-1 (n = 6). We calculate that this flow could wash the lens extracellular space by convection about once every 2 h and therefore might contribute to lens homeostasis and transparency.

Cultured bovine corneal epithelial cells express a functional aquaporin water channel

PURPOSE

Given recent physiological and in situ hybridization evidence for the presence of a water channel in corneal epithelium, this study was conducted to investigate its expression and characteristics using cultured bovine corneal epithelial cells (CBCEPCs).

METHODS

CBCEPCs were grown in DMEM containing 2 ng/ml fibroblast growth factor and 6% fetal bovine serum. To determine their osmotic permeability (Pf), cells were passaged onto rectangular glass coverslips, and anisotonically induced volume changes were monitored by light scattering. To investigate expression, poly(A+) RNA from CBCEPCs was injected into Xenopus laevis oocytes, and the Pf of the oocytes was determined.

RESULTS

For CBCEPCs challenged with a 10% hypotonic solution at 37 degrees C, the kinetic constant of volume change was k=0.52+/-0.04 seconds(-1), and the calculated Pf 72+/-6 microm/sec (n=16). The Pf of oocytes injected with water was 14+/-1.8 microm/sec (n=4); injection with poly(A+) RNA from CBCEPCs increased Pf to 77+/-6 microm/sec (n=6). This increase in Pf was inhibited by 72% (reduced to 22+/-1 microm/sec) by 0.3 mM HgCl2 and was inhibited by 56% to 58% by coinjection with aquaporin (AQP)5 antisense oligonucleotide.

CONCLUSIONS

The comparatively high Pf determined for CBCEPCs, the presence of mRNA encoding water channels, and sensitivity to mercurial agents are typical of the expression of functional water channels. The predominant message is for AQP5, although the evidence was consistent with the presence of additional water channels. These findings bring renewed support for the notion that the epithelium can contribute to corneal hydration homeostasis.

Effects of ciprofloxacin, streptomycin, and gentamicin on rabbit corneal transendothelial electrical potential difference

PURPOSE

A previous report suggested that high concentrations of ciprofloxacin in the anterior chamber may cause dose-dependent acute corneal decompensation. Therefore we evaluated the effect of varying concentrations of ciprofloxacin in the anterior chamber on the corneal endothelium and compared these effects with those of gentamicin and streptomycin.

METHODS

We assessed endothelial transport function by determining transendothelial electrical potential differences (TEPDs) of rabbit corneas. Our control solution was bicarbonate-buffered balanced saline with glucose (BSG), to which we added ciprofloxacin (50, 100, 125, and 150 microg/ml), gentamicin (1,000 and 2,000 microg/ml), and streptomycin (196, 437, and 696 microg/ml).

RESULTS

At high concentrations exceeding minimal inhibitory concentrations against 90% of common ocular isolates (MIC90), accelerated decay of TEPDs was seen with all three antibiotics. Adverse effects on TEPDs were noted at concentrations corresponding to >50 times MICs with ciprofloxacin and 40 x MICs with gentamicin, but only 2 times MICs with streptomycin.

CONCLUSION

Our study shows that concentrations of ciprofloxacin, gentamicin, and streptomycin below or equal to their MIC90 levels do not adversely affect endothelial transport function in a rabbit model.

Sodium, potassium, two chloride cotransport in corneal endothelium: characterization and possible role in volume regulation and fluid transport

PURPOSE

To search for membrane transporter proteins that could contribute to volume regulation and fluid transport by corneal endothelium. As an initial step, the authors have focused on Na+-K+-2Cl- cotransporters.

METHODS

Bovine corneal endothelial cells were cultured to confluence. 86Rubidium was used as a tracer for K+ uptake determinations; uptake values were normalized per milligram of cell protein.

RESULTS

Three components of K+ uptake were characterized: ouabain (1 mM) sensitive, bumetanide (0.1 mM) sensitive, and ouabain-bumetanide insensitive. Both the ouabain-sensitive and bumetanide-sensitive components increased in the presence of 26.2 mM HCO3-; 0.5 mM 4,4'-diisothiocyanato-stilbene-2,2'-disulfonic acid abolished this increase. The bumetanide-sensitive component was completely inhibited in the absence of Na+ or Cl-. This component was increased 33% by a 33% hypertonic solution and was decreased 38% by a 33% hypotonic solution. The protein kinase C activator phorbol 12-myristate 13-acetate decreased the activity of the cotransporter, whereas forskolin, in the presence of isobutylmethylxanthine, decreased it. Calyculin A (100 nM), an inhibitor of phosphatases 1 and 2a, produced a large (97%) activation of this component.

CONCLUSIONS

These results provided for the first time conclusive evidence for the presence of a Na+-K+-2Cl- cotransporter in corneal endothelium and of its possible involvement in volume-regulatory processes in these cells. Given the uptake values reported here, such cotransporter could contribute significantly to electrolyte transport and hence to fluid transport across this preparation.

Vinculin proteolysis unmasks an ActA homolog for actin-based Shigella motility

To generate the forces needed for motility, the plasma membranes of nonmuscle cells adopt an activated state that dynamically reorganizes the actin cytoskeleton. By usurping components from focal contacts and the actin cytoskeleton, the intracellular pathogens Shigella flexneri and Listeria monocytogenes use molecular mimicry to create their own actin-based motors. We raised an antibody (designated FS-1) against the FEFPPPPTDE sequence of Listeria ActA, and this antibody: (a) localized at the trailing end of motile intracellular Shigella, (b) inhibited intracellular locomotion upon microinjection of Shigella-infected cells, and (c) cross-reacted with the proteolytically derived 90-kD human vinculin head fragment that contains the Vinc-1 oligoproline sequence, PDFPPPPPDL. Antibody FS-1 reacted only weakly with full-length vinculin, suggesting that the Vinc-1 sequence in full-length vinculin may be masked by its tail region and that this sequence is unmasked by proteolysis. Immunofluoresence staining with a monoclonal antibody against the head region of vinculin (Vin 11-5) localized to the back of motile bacteria (an identical staining pattern observed with the anti-ActA FS-1 antibody), indicating that motile bacteria attract a form of vinculin containing an unmasked Vinc-1 oligoproline sequence. Microinjection of submicromolar concentrations of a synthetic Vinc-1 peptide arrested Shigella intracellular motility, underscoring the functional importance of this sequence. Western blots revealed that Shigella infection induces vinculin proteolysis in PtK2 cells and generates p90 head fragment over the same 1-3 h time frame when intracellular bacteria move within the host cell cytoplasm. We also discovered that microinjected p90, but not full-length vinculin, accelerates rates of pathogen motility by a factor of 3 +/- 0.4 in Shigella-infected PtK2 cells. These experiments suggest that vinculin p90 is a rate-limiting component in actin-based Shigella motility, and that supplementing cells with p90 stimulates rocket tail growth. Earlier findings demonstrated that vinculin p90 binds to IcsA (Suzuki, T.A., S. Saga, and C. Sasakawa. 1996. J. Biol. Chem. 271:21878-21885) and to vasodilator-stimulated phosphoprotein (VASP) (Brindle, N.P.J., M. R. Hold, J.E. Davies, C.J. Price, and D.R. Critchley. 1996. Biochem. J. 318:753-757). We now offer a working model in which proteolysis unmasks vinculin's ActA-like oligoproline sequence. Unmasking of this site serves as a molecular switch that initiates assembly of an actin-based motility complex containing VASP and profilin.