Subdiffusion of a sticky particle on a surface

Conventional diffusion (ΔR2(t))=2Dt gives way to subdiffusion (ΔR2(t))∼t(μ), 0<μ<1 when the waiting time distribution φ(τ) is nonintegrable. We have studied a model system, colloidal particles functionalized with DNA "sticky ends" diffusing on a complementary coated surface. We observe a crossover from subdiffusive to conventional behavior for (ΔR2(t)) and φ(τ) as temperature is increased near the particle-surface melting temperature consistent with a simple Gaussian distribution of sticky ends. Our results suggest that any system with randomness in its binding energy should exhibit subdiffusive behavior as it unbinds. This will strongly affect the kinetics of self-assembly.

The preventive effects of pulsed electromagnetic fields on diabetic bone loss in streptozotocin-treated rats

The present study was the first report demonstrating that pulsed electromagnetic field (PEMF) could partially prevent bone strength and architecture deterioration and improve the impaired bone formation in streptozotocin-induced diabetic rats. The findings indicated that PEMF might become a potential additive method for inhibiting diabetic osteopenia or osteoporosis.

INTRODUCTION

Diabetes mellitus (DM) can cause various musculoskeletal abnormalities. Optimal therapeutic methods for diabetic bone complication are still lacking. It is essential to develop more effective and safe therapeutic methods for diabetic bone disorders. Pulsed electromagnetic field (PEMF) as an alternative noninvasive method has proven to be effective for treating fracture healing and osteoporosis in non-diabetic conditions. However, the issue about the therapeutic effects of PEMF on diabetic bone complication has not been previously investigated.

METHODS

We herein systematically evaluated the preventive effects of PEMF on diabetic bone loss in streptozotocin-treated rats. Two similar experiments were conducted. In each experiment, 16 diabetic and eight non-diabetic rats were equally assigned to the control, DM, and DM + PEMF group. DM + PEMF group was subjected to daily 8-h PEMF exposure for 8 weeks.

RESULTS

In experiment 1, three-point bending test suggested that PEMF improved the biomechanical quality of diabetic bone tissues, evidenced by increased maximum load, stiffness, and energy absorption. Microcomputed tomography analysis demonstrated that DM-induced bone architecture deterioration was partially reversed by PEMF, evidenced by increased Tb.N, Tb.Th, BV/TV, and Conn.D and reduced Tb.Sp and SMI. Serum OC analysis indicated that PEMF partially prevented DM-induced decrease in bone formation. In experiment 2, no significant difference in the bone resorption marker TRACP5b was observed. These biochemical findings were further supported by the dynamic bone histomorphometric parameters BFR/BS and Oc.N/BS.

CONCLUSIONS

The results demonstrated that PEMF could partially prevent DM-induced bone strength and architecture deterioration and improve the impaired bone formation. PEMF might become a potential additive method for inhibiting diabetic osteoporosis.

In situ transmission electron microscopy imaging of grain growth in a platinum nanobridge induced by electric current annealing

We report an in situ transmission electron microscopy (TEM) imaging of grain growth in a Pt nanobridge induced by a high electric current density. The change in morphology at the nanoscale was recorded in real time together with the electrical characterization of the Pt nanobridge. We find a drop in the differential resistance as the voltage across the bridge is increased; TEM inspection shows that this coincides with thermally induced grain growth, indicating that a reduction of grain boundary scattering is the cause of the resistance decrease.

Myocardial oxidative stress contributes to transgenic β₂-adrenoceptor activation-induced cardiomyopathy and heart failure

BACKGROUND AND PURPOSE

While maintaining cardiac performance, chronic β-adrenoceptor activation eventually exacerbates the progression of cardiac remodelling and failure. We examined the adverse signalling pathways mediated by nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and reactive oxygen species (ROS) after chronic β₂-adrenoceptor activation.

EXPERIMENTAL APPROACH

Mice with transgenic β₂-adrenoceptor overexpression (β₂-TG) and non-transgenic littermates were either untreated or treated with an antioxidant (N-acetylcysteine, NAC) or NADPH oxidase inhibitors (apocynin, diphenyliodonium). Levels of ROS, phosphorylated p38 mitogen-activated protein kinase (MAPK), pro-inflammatory cytokines and collagen content in the left ventricle (LV) and LV function were measured and compared.

KEY RESULTS

β₂-TG mice showed increased ROS production, phosphorylation of p38 MAPK and heat shock protein 27 (HSP27), expression of pro-inflammatory cytokines and collagen, and progressive ventricular dysfunction. β₂-adrenoceptor stimulation similarly increased ROS production and phosphorylation of p38 MAPK and HSP27 in cultured cardiomyocytes. Treatment with apocynin, diphenyliodonium or NAC reduced phosphorylation of p38 MAPK and HSP27 in both cultured cardiomyocytes and the LV of β₂-TG mice. NAC treatment (500 mg·kg⁻¹ ·day⁻¹) for 2 weeks eliminated the up-regulated expression of pro-inflammatory cytokines and collagen in the LV of β₂-TG mice. Chronic NAC treatment to β₂-TG mice from 7 to 10 months of age largely prevented progression of ventricular dilatation, preserved contractile function (fractional shortening 37 ± 5% vs. 25 ± 3%, ejection fraction 52 ± 5% vs. 32 ± 4%, both P < 0.05), reduced cardiac fibrosis and suppressed matrix metalloproteinase activity.

CONCLUSION AND IMPLICATIONS

β₂-adrenoceptor stimulation provoked NADPH oxidase-derived ROS production in the heart. Elevated ROS activated p38 MAPK and contributed significantly to cardiac inflammation, remodelling and failure.

A dose-response study in animals to evaluate the anticoagulant effect of the stage 2 unfractionated heparin USP monograph change

The United States Pharmacopeia (USP) monograph for unfractionated heparin (UFH) was revised in October 2009. This revision was anticipated, based upon in vitro tests, to reduce UFH potency by approximately 10%. To study the potential in vivo consequences of the monograph change, we evaluated activated partial thromboplastin time (aPTT) and activated clotting time (ACT) responses in animals. Female mini-pigs and monkeys (n=8/species) were administered intravenously 60, 54, 48, or 42 U/kg and 50, 45, 40, or 35 U/kg "old" (pre-USP revision) UFH, respectively, in a Williams 4×4 crossover design. Blood samples for aPTT and ACT were collected at 15 min after dosing. The same study design was then repeated using "new" (post-USP revision) UFH. Mean "new" UFH aPTT and ACT values were generally lower than those for "old" UFH although individual animal responses varied considerably. The aPTT and ACT response was generally dose-proportional for both "old" and "new" UFH. These studies indicate that the USP monograph alteration for UFH may result in a modest reduction in the anticoagulant response across a population, but the variability in animal responses underscores the importance of individualization of clinical UFH dosing and the importance of anticoagulant test monitoring.

Simultaneous acquisition of gradient echo/spin echo BOLD and perfusion with a separate labeling coil

Arterial spin labeling-based cerebral blood flow imaging complements blood oxygenation level dependent (BOLD) imaging with a measure that is more quantitative and has better specificity to neuronal activation. Relative to gradient echo BOLD, spin echo BOLD has better spatial specificity because it is less biased to large draining veins. Although there have been many studies comparing simultaneously acquired cerebral blood flow data with gradient echo BOLD data in fMRI, there have been few studies comparing cerebral blood flow with SE BOLD and no study comparing all three. We present a pulse sequence that simultaneously acquires cerebral blood flow data with a separate labeling coil, gradient echo BOLD, and spin echo BOLD images. Simultaneous acquisition avoids interscan variability, allowing more direct assessment and comparison of each contrast's relative specificity and reproducibility. Furthermore, it facilitates studies that may benefit from multiple complementary measures.

Identification and genetic effect of haplotypes in the promoter region of porcine myostatin gene

Myostatin plays a pivotal role in controlling skeletal muscle mass in mammals. Polymorphisms in its promoter region likely impact on transcription and production traits. In this study, haplotypes involving three polymorphic sites in the promoter region of the porcine myostatin gene, namely at sites 435, 447 and 879, were identified and their effect on production traits, gene expression as well as on skeletal muscle traits were analysed. Four haplotypes were revealed and the linkage disequilibrium and evolutionary relationship were assessed. The results revealed that haplotypes A, B and C are predominant in Yorkshire and Landrace, Duroc and two Chinese indigenous pig breeds (Laiwu and Dapulian) respectively. The genotypes are associated with body weight on day 21 (BW21), average daily gain from birth to day 21 (ADG1) and average daily gain from day 21 to day 70 (ADG2) (P < 0.05) in Duroc pigs. The activity of haplotype A (pGL3-A) is significantly higher than other constructs in driving reporter gene transcription (P < 0.01). As compared with CC animals, the myostatin mRNA level in BC animals is relatively lower in both semimembranosus (SM) and semitendinosus (ST) skeletal muscles, and the difference was significant in the SM muscle (P < 0.01). Moreover, the mRNA levels of MyHCI, MyHCIIa, MyHCIIb and MyHCIIx and the muscle fibre diameter and density were also compared between BC and CC animals.

Heterologous expression of Alteromonas macleodii and Thiocapsa roseopersicina [NiFe] hydrogenases in Escherichia coli

HynSL from Alteromonas macleodii 'deep ecotype' (AltDE) is an oxygen-tolerant and thermostable [NiFe] hydrogenase. Its two structural genes (hynSL), encoding small and large hydrogenase subunits, are surrounded by eight genes (hynD, hupH and hypCABDFE) predicted to encode accessory proteins involved in maturation of the hydrogenase. A 13 kb fragment containing the ten structural and accessory genes along with three additional adjacent genes (orf2, cyt and orf1) was cloned into an IPTG-inducible expression vector and transferred into an Escherichia coli mutant strain lacking its native hydrogenases. Upon induction, HynSL from AltDE was expressed in E. coli and was active, as determined by an in vitro hydrogen evolution assay. Subsequent genetic analysis revealed that orf2, cyt, orf1 and hupH are not essential for assembling an active hydrogenase. However, hupH and orf2 can enhance the activity of the heterologously expressed hydrogenase. We used this genetic system to compare maturation mechanisms between AltDE HynSL and its Thiocapsa roseopersicina homologue. When the structural genes for the T. roseopersicina hydrogenase, hynSL, were expressed along with known T. roseopersicina accessory genes (hynD, hupK, hypC1C2 and hypDEF), no active hydrogenase was produced. Further, co-expression of AltDE accessory genes hypA and hypB with the entire set of the T. roseopersicina genes did not produce an active hydrogenase. However, co-expression of all AltDE accessory genes with the T. roseopersicina structural genes generated an active T. roseopersicina hydrogenase. This result demonstrates that the accessory genes from AltDE can complement their counterparts from T. roseopersicina and that the two hydrogenases share similar maturation mechanisms.

The Indian blood group system

The Indian blood group system (ISBT: IN/023) consists of two antithetical antigens: In(a) (IN1), which is present in approximately 10 percent of some Arab populations and in 3 percent of Bombay Indians, and its allelic antigen In(b) (IN2), an antigen of high incidence in all populations. In 2007, two new high-incidence antigens were identified as belonging to the IN blood group system, namely IN3 (INFI) and IN4 (INJA). The antigens in this system are located on CD44, a single-pass membrane glycoprotein that is encoded by the CD44 gene on chromosome 11 at position p13. The biologic function of CD44 is as a leukocyte homing receptor and cellular adhesion molecule. The In(a) and In(b) polymorphism represents a 252G>C substitution of CD44, encoding R46P, and lack of IN3 and IN4 results from homozygosity for mutations encoding H85Q and T163R in the CD44 gene. The high-frequency antigen AnWj (901009) has not been assigned to the Indian system, but either is located on an isoform of CD44 or is closely associated with it.

Directional differentiation of chicken primordial germ cells into adipocytes, neuron-like cells, and osteoblasts

Primordial germ cells (PGCs) are useful for producing transgenic chickens and preserving genetic material in avian species. In this study, we investigated the in vitro differentiation potential of chicken PGCs into different cell types. For differentiation into adipocytes, chicken PGCs were cultured for 21 days in induction media containing dexamethasone, insulin and/or 3-isobutyl-1-methylxanthine (IBMX), and differentiation rates ranging from 74% to 91% were identified by oil red-O and alkaline phosphatase (ALP) staining. For differentiation into neuron-like cells, chicken PGCs were cultured for 3 or 7 days in the induction media containing retinoic acid (RA) and IBMX, and differentiation rates ranging from 71% to 87% were identified by toluidine blue staining and immunohistochemical staining. For differentiation into osteoblasts, chicken PGCs were cultured for 15 or 21 days in the induction media containing desamethasone, beta-glycerol phosphate and/or vitamin C, and differentiation rates ranging from 47% to 79% were confirmed by Von Kossa, cytochemical and immunohistochemical staining. These data suggest that, like mammalian PGCs, chicken PGCs can differentiate into different cell types in vitro.

Abstract P2-09-32: Estrogen Receptor-Related Genes Are Important Predictors of Response to Neo-Adjuvant Chemotherapy in Breast Cancer

Background: Clinical data suggest a contribution of estrogen receptor (ER) to chemotherapy response. However, ER status alone is not perfectly predictive, and there is an urgent need for more reliable markers of chemotherapy responsiveness. In this study, we set out to find novel ER-related genes in predicting chemotherapy response by microarrays, hoping to provide more robust multi-variable prediction to chemotherapy. Material and Methods: One hundred and ten patients with stage II-III breast cancer were included, receiving preoperative four cycles of weekly PCb (paclitaxel plus carboplatin) regimen. Pretreatment gene expression profiling was performed with gene microarrays on core biopsy specimens. 55 training cases were used for marker discovery and to identify any ER-related genes that might be associated with response (“training cases”), and the other 55 patients were available as an independent validation set (“validation cases”) to test whether the ER-related genes do predict pCR in protein levels by immunohistochemistry (IHC). Results: In the training cases, the yield of total RNA was insufficient to assay in 16 patients and 8 chips failed in the quality check (QC) process. Therefore, gene expression profile from 31 samples were available for this study. The overall pCR rate in the 86 patients was 19.7% (n=17, 6 cases of pCR in training set and 11 pCR in validation set). In the training set, by Significance Analysis of Microarrays (SAM), 300 probes (231 genes) were identified as differentially expressed between pCR versus non-pCR when fold change &gt; 2. There were 20 differentially expressed genes, setting fold change &gt; 3. Among these 20 genes, TFF1, ESR1, GATA3, TFF3 were found as ER-related. In 55 independent validation cases, univariate analysis indicated that clinical variables and ER-related genes, including ER, PR, GATA3, TFF1 and TFF3 were all significantly associated with pCR (Pearson x2, P&lt;0.001, P=0.013, P&lt;0.001, P&lt;0.001, P&lt;0.001). Multivariate logistic regression model showed that ER (P=0.016) remained significantly associated with complete remission. In spearman analysis, these 5 ER-related genes were significantly correlated with each other (P&lt;0.05). It was found that pCR rate was as high as 80% (4/5) when these 5 factors were all negative. In contrast, these 5 factors were all positive in 7 of 9 PD/SD patients.

Discussion: ER combined with ER-related genes expression status may provide important predictive value of response to neoadjuvant chemotherapy and allows to identify a subgroup of patients who might highly benefit from chemotherapy and who might be resistant to it.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P2-09-32.

Abstract P6-04-12: Pathway Analysis of Primary Human Triple-Negative Breast Cancers

BACKGROUND: Breast cancer is a complex, heterogeneous disease due to vast differences in cellular origin, genetic mutations, metastatic potential, and disease progression. Triple-negative breast cancer (TNBC) is a subtype defined by negative expression of estrogen receptor, progesterone receptor, and human epidermal growth factor receptor-2. Because of its aggressive nature and poor prognosis, TNBC has gained recent attention within the oncology community. Tissue expression profiling with microarrays is a robust and straightforward method to study molecular features of TNBC at a systems level. The goal of this project was to further understand the pathogenesis of TNBC through comprehensive characterization of molecular and pathway signatures, based on analysis of freshly frozen and paraffin-embedded primary tumors from 20 TNBC patients, compared with syngeneic normal breast samples.

METHODS: Microarrary profiling of quadruplet sets of samples (freshly frozen and paraffin-embedded; 80 samples total) was conducted using the Affymetrix Human Gene 1.0 ST array. The differential expression profile of cancer vs. syngeneic normal tissue was calculated for each patient, as well as for combined samples, using the unpaired t-test. Pathway analyses based on gene expression profiling were performed using Pathway Studio (Ariadne Genomics, Inc). Functional enrichment was performed using Fisher's Exact test and Mann-Whitney test.

RESULTS: This analysis demonstrated that TNBC is characterized by a distinct molecular signature which includes genes and pathways of DNA repair, cell cycle, and energy production. Several DNA repair genes were upregulated by at least 2.3-fold, including CHEK1, BLM, NEIL3, PARP1, FANCI, FANCD2 and EXO1 (P &lt;.0001 for each). While several genes in excision-repair pathways (DDB2, RPA1, XAB2 and RAB23A) were downregulated, most genes involved in homologous recombination (BRCA1, BRCA2, RAD54B, RAD51, and RAD51L1), DNA repair synthesis (POLQ and PCNA), and DNA mismatch repair (MLH1, MSH3, PMS1 and PMS2) were upregulated. Analysis of the PARP1 pathway revealed that most upstream and downstream neighbors of PARP1 were significantly upregulated between 2- and 4.5-fold in TNBC. Consistent with previous observations, PARP1 was significantly upregulated by 2.5-fold (P &lt; .0001) in TNBC. Genes involved with cell cycle checkpoint control were also significantly altered, including 4.4-fold, 3.6-fold, and 6.8-fold upregulation of CCNB1, CDC2, and TOP2A, respectively (P &lt; .0001 for each). Of genes involved in metabolic pathways, those involved in purine, folate and pyrimidine metabolism demonstrated changes consistent with active proliferation of TNBC cells. In addition, expression patterns related to inflammation (leukocyte migration, lymphocyte activation, macrophage chemotaxis) and angiogenesis were observed. This finding is consistent with previously described activation of the NFkB pathway and suggestive of an inflammatory component in the pathogenesis of TNBC. CONCLUSIONS : TNBC appears to be characterized by distinct alterations in DNA repair, cell cycle regulation, and metabolism, thus providing a molecular basis for identifying novel therapeutic strategies for this disease.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P6-04-12.