Mechanisms mediating renal sympathetic nerve activation in obesity-related hypertension

Excessive renal sympathetic nerve activation may be one of the mechanisms underlying obesity-related hypertension. Impaired baroreflex sensitivity, adipokine disorders-such as leptin, adiponectin, and resistin-activation of the renin-angiotensin system, hyperinsulinemia, insulin resistance, and renal sodium retention present in obesity increase renal sympathetic nerve activity, thus contributing to the development of hypertension. Renal sympathetic denervation reduces both renal sympathetic activity and blood pressure in patients with obesity-related hypertension.

Adaptive semantic tag mining from heterogeneous clinical research texts

OBJECTIVES

To develop an adaptive approach to mine frequent semantic tags (FSTs) from heterogeneous clinical research texts.

METHODS

We develop a "plug-n-play" framework that integrates replaceable unsupervised kernel algorithms with formatting, functional, and utility wrappers for FST mining. Temporal information identification and semantic equivalence detection were two example functional wrappers. We first compared this approach's recall and efficiency for mining FSTs from ClinicalTrials.gov to that of a recently published tag-mining algorithm. Then we assessed this approach's adaptability to two other types of clinical research texts: clinical data requests and clinical trial protocols, by comparing the prevalence trends of FSTs across three texts.

RESULTS

Our approach increased the average recall and speed by 12.8% and 47.02% respectively upon the baseline when mining FSTs from ClinicalTrials.gov, and maintained an overlap in relevant FSTs with the base- line ranging between 76.9% and 100% for varying FST frequency thresholds. The FSTs saturated when the data size reached 200 documents. Consistent trends in the prevalence of FST were observed across the three texts as the data size or frequency threshold changed.

CONCLUSIONS

This paper contributes an adaptive tag-mining framework that is scalable and adaptable without sacrificing its recall. This component-based architectural design can be potentially generalizable to improve the adaptability of other clinical text mining methods.

[Carotid intima-media thickness and estimated glomerular filtration rate in hypertensive patients]

OBJECTIVE

To determine the association between carotid atherosclerosis and renal function in hypertensive patients.

METHODS

A total of 2 809 hypertensive patients aged (56.59±10.79) years were enrolled. Carotid intima-media thickness (cIMT) was derived via B-mode ultrasonography and chronic kidney disease (CKD) was evaluated by the estimated glomerular filtration rate (eGFR) with Cockcroft- Gault method. The patients were divided into 3 groups: a normal group, a thick group, and a plaque group according to the results of carotid ultrasonography.

RESULTS

The eGFR of the normal group was (111.09±25.61) mL/(min.1.73m(2)), that of the thick group and the plaque group was (94.45±27.14) mL/(min.1.73m(2)) and (85.98±26.92) mL/ (min.1.73m(2)). Binary logistic analysis showed that age (OR=3.590), smoking status (OR=1.543), systolic blood pressure (OR=1.018), diastolic blood pressure (OR=0.977), fasting plasma glucose (OR=1.132), triglyceride (OR=0.873) and eGFR (OR=0.986) were significantly correlated with cIMT. Subgroup analyses on different genders showed that eGFR was a significant independent risk factor in men (OR=0.991) but not in women.

CONCLUSION

The thicker the cIMT, the lower the eGFR in hypertensive patients. With the development of cIMT, eGFR gradually decreases and contributes to the occurrence and development of early-stage atherosclerosis in hypertensive patients.

A distribution-based method for assessing the differences between clinical trial target populations and patient populations in electronic health records

OBJECTIVE

To improve the transparency of clinical trial generalizability and to illustrate the method using Type 2 diabetes as an example.

METHODS

Our data included 1,761 diabetes clinical trials and the electronic health records (EHR) of 26,120 patients with Type 2 diabetes who visited Columbia University Medical Center of New-York Presbyterian Hospital. The two populations were compared using the Generalizability Index for Study Traits (GIST) on the earliest diagnosis age and the mean hemoglobin A1c (HbA1c) values.

RESULTS

Greater than 70% of Type 2 diabetes studies allow patients with HbA1c measures between 7 and 10.5, but less than 40% of studies allow HbA1c<7 and fewer than 45% of studies allow HbA1c>10.5. In the real-world population, only 38% of patients had HbA1c between 7 and 10.5, with 12% having values above the range and 52% having HbA1c<7. The GIST for HbA1c was 0.51. Most studies adopted broad age value ranges, with the most common restrictions excluding patients >80 or <18 years. Most of the real-world population fell within this range, but 2% of patients were <18 at time of first diagnosis and 8% were >80. The GIST for age was 0.75.

CONCLUSIONS

We contribute a scalable method to profile and compare aggregated clinical trial target populations with EHR patient populations. We demonstrate that Type 2 diabetes studies are more generalizable with regard to age than they are with regard to HbA1c. We found that the generalizability of age increased from Phase 1 to Phase 3 while the generalizability of HbA1c decreased during those same phases. This method can generalize to other medical conditions and other continuous or binary variables. We envision the potential use of EHR data for examining the generalizability of clinical trials and for defining population-representative clinical trial eligibility criteria.

Microchannel Deformation of Polymer Chip in In-Mold Bonding

Microchannel deformation is a problem which often occurs in the thermal bonding of polymer microfluidic chip, and which is significantly determined by bonding parameters. In this paper, numerical analysis of the microchannel deformation in the process of in-mold bonding polymer chip was conducted, using Young's modulus and shear relaxation modulus of polymethylmethacrylate (PMMA) obtained in creep tests. Adhesion between the top and two lateral walls of microchannel was observed in the results, which can be attributed mainly to the viscoelastic deformation of PMMA. It was also revealed that the maximum percent deformation of microchannel is in height, and that bonding temperature had greater effect on the deformation of microchannel than bonding pressure and bonding time. The deformation of microchannel in simulation were consistent with those of experiment under the optimized parameters of 105 °C, 2 MPa and 240 s.

Suppression of DHT-induced paracrine stimulation of endothelial cell growth by estrogens via prostate cancer cells

BACKGROUND

Androgen modulation of angiogenesis in prostate cancer may be not directly mediated by androgen receptor (AR) as AR is not detected in the prostatic endothelial cells.

METHODS

We examined the paracrine stimulation of cell proliferation by prostate tumor cells and its modulation by androgen and estrogens in a murine endothelial cell line (MEC) that does not express AR.

RESULTS

Tumor cell conditioned media (TCM) collected from LAPC-4 or LNCaP prostatic tumor cells produced a time- and concentration-dependent induction of cell growth in MECs, which was parallel to the VEGF concentration in the TCM. This TCM-induced cell growth in MECs was enhanced by the treatment of prostatic tumor cells with dihydrotestosterone (DHT). Both the TCM-stimulation and DHT-enhancement effects in MECs were completely blocked by SU5416, a specific VEGF receptor antagonist. Co-administration of 17α-estradiol or 17β-estradiol with DHT in prostatic tumor cells completely inhibited the DHT-enhancement effect while treatment with DHT, 17α-estradiol or 17β-estradiol did not produce any significant direct effect in MECs. Moreover, administration of 17α-estradiol or 17β-estradiol in xenograft animals with LAPC-4 or LNCaP prostate tumor significantly decreased the microvessel number in the tumor tissues.

CONCLUSIONS

Our study indicated that prostate tumor cells regulate endothelial cell growth through a paracrine mechanism, which is mainly mediated by VEGF; and DHT is able to modulate endothelial cell growth via tumor cells, which is inhibited by 17α-estradiol and 17β-estradiol. Thus, both17α-estradiol and 17β-estradiol are potential agents for anti-angiogenesis therapy in androgen-responsive prostate cancer.

Feasibility of feature-based indexing, clustering, and search of clinical trials. A case study of breast cancer trials from ClinicalTrials.gov

BACKGROUND

When standard therapies fail, clinical trials provide experimental treatment opportunities for patients with drug-resistant illnesses or terminal diseases. Clinical Trials can also provide free treatment and education for individuals who otherwise may not have access to such care. To find relevant clinical trials, patients often search online; however, they often encounter a significant barrier due to the large number of trials and in-effective indexing methods for reducing the trial search space.

OBJECTIVES

This study explores the feasibility of feature-based indexing, clustering, and search of clinical trials and informs designs to automate these processes.

METHODS

We decomposed 80 randomly selected stage III breast cancer clinical trials into a vector of eligibility features, which were organized into a hierarchy. We clustered trials based on their eligibility feature similarities. In a simulated search process, manually selected features were used to generate specific eligibility questions to filter trials iteratively.

RESULTS

We extracted 1,437 distinct eligibility features and achieved an inter-rater agreement of 0.73 for feature extraction for 37 frequent features occurring in more than 20 trials. Using all the 1,437 features we stratified the 80 trials into six clusters containing trials recruiting similar patients by patient-characteristic features, five clusters by disease-characteristic features, and two clusters by mixed features. Most of the features were mapped to one or more Unified Medical Language System (UMLS) concepts, demonstrating the utility of named entity recognition prior to mapping with the UMLS for automatic feature extraction.

CONCLUSIONS

It is feasible to develop feature-based indexing and clustering methods for clinical trials to identify trials with similar target populations and to improve trial search efficiency.

Age- and gender dependent association between components of metabolic syndrome and subclinical arterial stiffness in a Chinese population

BACKGROUND

The aim of this study was to estimate the relationship between arterial stiffness and components of metabolic syndrome (MetS) in different age- and gender groups.

METHODS

A total of 12,900 Chinese adults aged 20-79 years were recruited and stratified on the basis of gender and age. All participants underwent the measurement of waist circumference, blood pressure (BP), brachial-ankle pulse wave velocity (baPWV; an indicator of arterial stiffness), and blood chemistry. Multiple linear regression analysis was performed to evaluate the relationship between baPWV and above variables, to determine the relative influence of each component of MetS on baPWV.

RESULTS

The prevalence of metabolic disorders except for low high-density lipoprotein cholesterol (HDL-C) was much higher in men than in women. All participants with MetS or any component of MetS except for low HDL-C had higher baPWV. BP was positively correlated with baPWV in all groups, while HDL-C was not correlated with baPWV in any groups. In addition, fasting glucose was related to baPWV in middle-aged adults and the elderly. Waist circumference had a positive association with baPWV in middle-aged adults and young men, triglyceride levels showed a significant correlation with baPWV in middle-aged women and young men. Of the MetS components, elevated BP was the strongest predictor of baPWV.

CONCLUSION

The prevalence of metabolic disorders and the association between baPWV and metabolic variables are dependent on age and gender. Different components of MetS exert distinct impacts on the baPWV in different age- and gender groups, with BP being the strongest predictor. It is suggested that age and gender should be taken into accounted in the management of MetS aiming to reduce subsequent complications.

Androgen stimulates endothelial cell proliferation via an androgen receptor/VEGF/cyclin A-mediated mechanism

Growing evidences support that androgen displays beneficial effects on cardiovascular functions although the mechanism of androgen actions remains to be elucidated. Modulation of endothelial cell growth and function is a potential mechanism of androgen actions. We demonstrated in the present study that androgens [dihydrotestosterone (DHT) and testosterone], but not 17β-estradiol, produced a time- and dose-dependent induction of cell proliferation in primary human aortic endothelial cells (HAECs) as evident by increases in viable cell number and DNA biosynthesis. Real-time qRT-PCR analysis showed that DHT induced androgen receptor (AR), cyclin A, cyclin D1, and vascular endothelial growth factor (VEGF) gene expression in a dose- and time-dependent manner. The addition of casodex, a specific AR antagonist, or transfection of a specific AR siRNA blocked DHT-induced cell proliferation and target gene expression, indicating that the DHT effects are mediated via AR. Moreover, coadministration of SU5416 to block VEGF receptors, or transfection of a specific VEGF-A siRNA to knockdown VEGF expression, produced a dose-dependent blockade of DHT induction of cell proliferation and cyclin A gene expression. Interestingly, roscovitine, a selective cyclin-dependent kinase inhibitor, also blocked the DHT stimulation of cell proliferation with a selective inhibition of DHT-induced VEGF-A expression. These results indicate that androgens acting on AR stimulate cell proliferation through upregulation of VEGF-A, cyclin A, and cyclin D1 in HAECs, which may be beneficial to cardiovascular functions since endothelial cell proliferation could assist the repair of endothelial injury/damage in cardiovascular system.

Interactions between stem cells and their niche in the Drosophila ovary

The Drosophila ovary contains at least three types of active stem cells, namely, germ-line stem cells (GSCs), escort stem cells (ESCs), and follicular stem cells (FSCs), which work together to efficiently assemble egg chambers. Among the three stem cell types, the GSC is among the first shown to be controlled by the niche due to its easy identification and welldefined surrounding cells. We have shown that the niche controls GSC self-renewal, anchorage, aging, and competition, and the GSC also signals back to the niche for its maintenance. The FSC is an attractive model for studying epithelial stem cell regulation and signal integration because we have shown that it resembles mammalian epithelial stem cells and requires multiple signaling pathways for its self-renewal. In this chapter, we have highlighted the findings of our studies on interactions between Drosophila ovarian stem cells and their niches during normal development and aging and on stem cell competition for niche occupancy. We further discuss their implications in general stem cell biology and future directions in this exciting area.

Topography-guided treatment of decentered laser ablation using LaserSight's excimer laser

PURPOSE

To assess the efficacy of topography-guided laser ablation for correction of previously decentered laser ablation using LaserSight's excimer laser.

METHODS

Re-treatment was performed to correct decentered ablation using LaserSight's excimer laser for 18 patients who previously underwent LASIK surgery for myopia correction in both eyes. For each patient, only the decentered eye was re-treated while the other asymptomatic eye forms a control group for this study. Measurements were conducted on ablation center, best spectacle-corrected visual acuity (BSCVA), contrast sensitivity and corneal aberrations pre- and post-operatively.

RESULTS

For the retreated 18 eyes, the mean decentration was significantly reduced from 1.32+/-0.28mm to 0.61+/-0.23mm post-operatively (t=16.24, p<0.001), and with a significant improvement in mean BSCVA from 0.08+/-0.09 logMAR to 0.01+/-0.11 logMAR (t=4.58, p<0.001). The post-operative contrast sensitivity at the spatial frequencies (SF) of 1.00 and 0.70 was significantly improved (p<0.05 for both SFs). Corneal higher-order aberrations (HOAs), including the coma-like aberrations and spherical aberration, were decreased. In comparing the measurements for the retreated group to those for the control group, no significant differencewas found either in decentration or in BSCVA, but the contrast sensitivity at 0.70 was lower and the level of corneal aberrations was higher.

CONCLUSIONS

Topography-guided ablation with LaserSight excimer laser is effective to correct decentered ablation. However, the re-treated eye is still inferior to the eye with originally centered ablation in corneal optical quality or visual performance.

CNS atypical teratoid/rhabdoid tumor registry: An update

12507

Background: Atypical teratoid/rhabdoid tumor (AT/RT) is a highly malignant tumor of the central nervous system (CNS) in childhood, comprising up to 20% of malignant CNS tumors in patients < 3 years old. Although aggressive approaches including surgery, chemotherapy, intrathecal chemotherapy, high dose chemotherapy with hematopoietic stem cell transplant (HD-HSCT) and/or radiation have resulted in prolonged survival, overall survival remains poor. Methods: We reviewed pediatric patients with AT/RT on an IRB- approved registry formed in 1995 with new insight based on updated outcomes and additional patient enrollment. Upon patient entry, the managing physician submitted pertinent medical records for data abstraction. Physicians were contacted in accordance with privacy regulations for updated records. The Kaplan-Meier method was used to estimate survival time (from diagnosis to death or most recent status update) and groups were compared using the log-rank test at a significance level of p<0.05 with SAS® software version 9.1. Results: Analysis was conducted on 73 patients with a 4:3 male to female ratio. Age at diagnosis ranged from 5 days to 234 months, median = 19 months. Twenty-five patients have no evidence of disease, median 59 months from diagnosis (range 10–140). Forty-three patients (59%) developed recurrent or progressive disease; 6 of these patients are alive at a median of 28 months from recurrence (range 4–38). Forty-four patients (60%) are dead of disease; median time to death was 7 months from diagnosis (range 0–62). Factors correlating with survival are: primary tumor site not in spinal cord (p=0.029), lack of metastatic disease (p=0.024), gross total resection (p<0.001), and upfront radiation particularly in children < 3 years old (p<0.001). HD-HSCT appears to result in improved survival in children < 3 years of age who do not receive radiation, though the small sample size does not yield a statistically significant survival advantage. Conclusions: In treatment of AT/RT, extent of surgical resection and upfront radiation are beneficial for overall survival, particularly in young children. Early information regarding upfront HD-HSCT in lieu of radiation for children < 3 years of age with AT/RT suggests it may be effective. Prospective studies are warranted to further investigate this treatment.

No significant financial relationships to disclose.

Retinogeniculate connections: A balancing act between connection specificity and receptive field diversity

Retinogeniculate connections are one of the most striking examples of connection specificity within the visual pathway. In almost every connection there is one dominant afferent cell per geniculate cell, and both afferent and geniculate cells have very similar receptive fields. The remarkable specificity and strength of retinogeniculate connections have inspired comparisons of the lateral geniculate nucleus (LGN) with a simple relay that connects the retina with the visual cortex. However, because each retinal ganglion cell diverges to innervate multiple cells in the LGN, most geniculate cells must receive additional inputs from other retinal afferents that are not the dominant ones. These additional afferents make weaker connections and their receptive fields are not as perfectly matched with the geniculate target as the dominant afferent. We argue that these 'match imperfections' are important to create receptive field diversity among the cells that represent each point of visual space in the LGN. We propose that the convergence of dominant and weak retinal afferents in the LGN multiplexes the array of retinal ganglion cells by creating receptive fields that have a richer range of positions, sizes and response time courses than those available at the ganglion cell layer of the retina.

On the Number of Genes Controlling the Grass Stage in Longleaf Pine

The grass stage is an inherent and distinctive developmental trait of longleaf pine (Pinus palustris), in which height growth in the first few years after germination is suppressed. In operational forestry practice the grass stage extends for two to several years and often plays a role in planting failures and decisions to plant alternative species. Interspecies hybrids involving loblolly (P. taeda) and slash (P. elliottii var. elliottii) pines have been investigated as a means to produce planting stock with improved early height growth and to develop backcross populations for advanced generation breeding. We have reevaluated data from several interspecies populations, with the objective of estimating the number of genes contributing to the difference in first-year height growth between longleaf and loblolly pines. Estimates based on means and variances of parental and interspecies hybrid and backcross families suggest a minimum of 4 to 10 genes with standard errors less than half the estimates. These results suggest that the grass stage has evolved through the accumulation of alleles at several loci, each with small effects on various components of first-year height growth. Given the complexity of the grass-stage trait, tree breeders may need to combine genetic marker analysis with recurrent backcross breeding to efficiently develop longleaf pine planting stock for improved reforestation.

Mapping quantitative trait loci controlling early growth in a (longleaf pine x slash pine) x slash pine BC(1) family

Random amplified polymorphic DNA (RAPD) markers were employed to map the genome and quantitative trait loci controlling the early growth of a pine hybrid F(1) tree ( Pinus palustris Mill. x P. elliottii Engl.) and a recurrent slash pine tree ( P. elliottii Engl.) in a (longleaf pine x slash pine) x slash pine BC(1) family consisting of 258 progeny. Of the 150 hybrid F(1) parent-specific RAPD markers, 133 were mapped into 17 linkage groups covering a genetic distance of 1,338.2 cM. Of the 116 slash pine parent-specific RAPD markers, 83 were mapped into 19 linkage groups covering a genetic distance of 994.6 cM. A total of 11 different marker intervals were found to be significantly associated with 13 of the 20 traits on height and diameter growth using MAPMAKER/QTL. Nine of the eleven marker intervals were unique to the hybrid parent 488 genome, and two were unique to the recurrent parent 18-27 genome. The amount of phenotypic variance explained by the putative QTLs ranged from 3.6% to 11.0%. Different QTLs were detected at different ages. Two marker intervals from the hybrid parent 488 were found to have QTL by environment interactions.

The natural history of diabetic peripheral neuropathy determined by a 12 year prospective study using vibration perception thresholds

The development and long term progression of diabetic peripheral neuropathy was studied using vibration perception threshold (VPT) as a validated measure. Three hundred and ninety-two patients had a normal age corrected VPT (12.1 +/- 3.7 volts) at baseline, with an age corrected logarithmic VPTscore < 12. 19.9% developed an abnormal VPT over a 12 year period, increasing from 14.2 +/- 3.7 volts (VPTscore 10.4 +/- 0.6) at baseline to 35.9 +/- 9.5 volts (VPTscore 12.6 +/- 0.45) at follow up (P = 0.0001), and from 10.1 +/- 3.7volts (VPTscore 9.4 +/- 0.8) to 14.2 +/- 4.7 (VPTscore 9.8 +/- 0.8) in the rest. Over 80% thus retained a "normal" VPT after a mean diabetes duration of 16 years despite only average glycaemic control, suggesting that non-ideal long term glycaemic control leads to neuropathy in a subset of predisposed patients. VPT was correlated in 123 diabetic patients with definitive criteria for neuropathy and a range of quantitative sensory and autonomic tests. 62/63 patients with abnormal VPT fulfilled neuropathy criteria; of patients with normal VPT who fulfilled neuropathy criteria, all had at least one abnormal thermal threshold test result. We conclude that a combination of log-transformed VPT values (VPTscore > 10.1) and thermal thresholds can identify diabetic patients at risk of developing peripheral neuropathy and select patients likely to benefit from prophylaxis in clinical trials.