Two distinct filopodia populations at the growth cone allow to sense nanotopographical extracellular matrix cues to guide neurite outgrowth

BACKGROUND The process of neurite outgrowth is the initial step in producing the neuronal processes that wire the brain. Current models about neurite outgrowth have been derived from classic two-dimensional (2D) cell culture systems, which do not recapitulate the topographical cues that are present in the extracellular matrix (ECM) in vivo. Here, we explore how ECM nanotopography influences neurite outgrowth. METHODOLOGY/PRINCIPAL FINDINGS We show that, when the ECM protein laminin is presented on a line pattern with nanometric size features, it leads to orientation of neurite outgrowth along the line pattern. This is also coupled with a robust increase in neurite length. The sensing mechanism that allows neurite orientation occurs through a highly stereotypical growth cone behavior involving two filopodia populations. Non-aligned filopodia on the distal part of the growth cone scan the pattern in a lateral back and forth motion and are highly unstable. Filopodia at the growth cone tip align with the line substrate, are stabilized by an F-actin rich cytoskeleton and enable steady neurite extension. This stabilization event most likely occurs by integration of signals emanating from non-aligned and aligned filopodia which sense different extent of adhesion surface on the line pattern. In contrast, on the 2D substrate only unstable filopodia are observed at the growth cone, leading to frequent neurite collapse events and less efficient outgrowth. CONCLUSIONS/SIGNIFICANCE We propose that a constant crosstalk between both filopodia populations allows stochastic sensing of nanotopographical ECM cues, leading to oriented and steady neurite outgrowth. Our work provides insight in how neuronal growth cones can sense geometric ECM cues. This has not been accessible previously using routine 2D culture systems.

HETEROGENEITY IN VIRUS EXPRESSION, TUMORIGENICITY, AND IN VITRO GROWTH PROPERTIES OF DRUG-RESISTANT CLONES OF AN RIII MOUSE MAMMARY TUMOR CELL LINE

Four 8-azaguanine (AG)-resistant and 5-bromodeoxyuridine (BUdR)-resistant clones of a mouse mammary adenocarcinoma cell line, RIII 7387, were developed and analyzed for their tumorigenic properties, in vitro characteristics, and virus expression. These characteristics were analyzed for relationships of any of the cellular parameters and the ability of these lines to produce tumors in syngeneic animals.^ The results of this study demonstrated that the parental line consists of a heterogeneous population of cells. Doubling times, saturation densities, and 2-deoxy-D-glucose uptake varied between sublines. In addition, while all sublines were found to express both B-type and C-type viral antigenic markers, levels of the major B-type and C-type viral proteins varied in the subclones. The sublines also differed markedly in their response to the presence of dexamethasone, glutathione, and insulin in the tissue culture medium.^ Variations in retrovirus expression were convirmed by electron microscopy. Budding and extracellular virus particles were seen in the majority of the cell lines. Virus particles in one of the BUdR-resistant lines, BUD9, were found however, only in inclusions and vacuoles. The AG-resistant subline AGE11 was observed to be rich in intracytoplasmic A particles. The examination of these cell lines for the presence of retroviral RNA-dependent DNA polymerase (RT) activity revealed that some B-type RT activity could be found in the culture fluid of most of the cell lines but that little C-type RT activity could be found suggesting that the C-type virus particles expressed by these RIII clones contain a defective RT.^ Tumor clones also varied in their ability to form tumors in syngeneic RIII mice. Tumor incidence ranged from 50% to 100%. The majority of the tumors regressed within 30 days post infection.^ Statistical analysis indicated that while these clones varied in their characteristics, there was no correlation between the ability of these cell lines to form tumors in syngeneic mice and any of the other characteristics examined.^ These studies have confirmed and extended the growing evidence that tumors, regardless of their natural origin, consist of heterogeneous subpopulations of cells which may vary widely in their in vitro growth behavior, their antigenic expression, and their malignant properties. ^

The Great Moderation and the Relationship between Output Growth and Its Volatility

This study examines the effect of the Great Moderation on the relationship between U.S. output growth and its volatility over the period 1947 to 2006. First, we consider the possible effects of structural change in the volatility process. In so doing, we employ GARCH-M and ARCH-M specifications of the process describing output growth rate and its volatility with and without a one-time structural break in volatility. Second, our data analyses and empirical results suggest no significant relationship between the output growth rate and its volatility, favoring the traditional wisdom of dichotomy in macroeconomics. Moreover, the evidence shows that the time-varying variance falls sharply or even disappears once we incorporate a one-time structural break in the unconditional variance of output starting 1982 or 1984. That is, the integrated GARCH effect proves spurious. Finally, a joint test of a trend change and a one-time shift in the volatility process finds that the one-time shift dominates.

Functional studies of insulin-like growth factor binding protein 2 pathway in glioma progression

Comparison of gene expressing profiles between gliomas with different grades revealed frequent overexpression of insulin-like growth factor binding protein 2 (IGFBP2) in glioblastomas (GBM), in which uncontrolled cell proliferation, angiogenesis, invasion and anti-apoptosis are hallmarks. Using the glia-specific gene transfer transgenic mouse and the stable LN229(BP2) GBM cell lines, we found that IGFBP2 by itself cannot transform cells in vitro and in vivo. IGFBP2 had growth inhibitory effects on mouse primary neural progenitors, but overexpression of IGFBP2 had no effect on GBM cells. ^ Although IGFBP2 does not initiate gliomagenesis, using tissue array technology, we observed strong correlation between IGFBP2 overexpression and VEGF up-regulation in human diffuse gliomas. Furthermore, overexpression of IGFBP2 in GBM cells not only enhanced VEGF expression but also increased the malignant potential of U87 MG cells in our angiogenesis xenograft animal model. ^ In parallel to these studies, using established stable SNB19 GBM cells that overexpress IGFBP2, we found that IGFBP2 significantly increased invasion by induction of matrix metalloproteinase-2 (MMP-2) as well as other invasion related genes, providing evidence that IGFBP2 contributes to glioma progression in part by enhancing MMP-2 gene transcription and in turn tumor cell invasion. ^ Finally, we found that primary filial cells infected with an anti-sense IGFBP2 construct have markedly increased sensitivity to γ irradiation and reduced Akt activation. On the other hand, SNB19(BP2) stable lines have consistently increased levels of Akt and NFkB activation, suggesting that one possible mechanism for anti-apoptosic function of IGFBP2 is through the activation of Akt and NFkB. Beside this, what is especially interesting is the finding that Akt protein was cleaved and inactivated during apoptosis by caspases, and IGFBP2 can prevent Akt cleavage, revealing another possible mechanism through it IGFBP2 exhibit strong antiapoptotic effects. Our data showed that IGFBP2 is a specific substrate for caspase-3, raising the possibility that IGFBP2 may inhibit apoptosis by a suicide mechanism. ^ In summary, using cellular, genomics, and molecular approaches, this thesis documented the potential roles of IGFBP2 in glioma progression. Our findings shed light on an important biological aspect of glioma progression and may provide new insights useful for the design of novel mechanism-based therapies for GBM. ^

HRGbeta1 inhibits metastasis of breast cancer cell lines, one of which exhibits lineage infidelity

Recent publications have questioned the origin of the MDA-MB-435 breast cancer cell line and have suggested that it is of melanocyte origin rather than breast epithelial origin. The data presented herein show unequivocally that MDA-MB-435 does express breast epithelial markers and produces milk-specific lipids. The data also indicated that MDA-MB-435 does express some melanocyte proteins but this expression occurs in the same MDA-MB-435 cells that express breast epithelial proteins. Although MDA-MB-435 does not strictly adhere to a breast lineage, it does retain breast specific markers and is thus valid as an experimental cell line in breast cancer studies. ^ Heregulinβ1 (HRGβ1) has been shown to both stimulate and inhibit breast tumorigenic and metasastasic phenotypes. Some studies used only the EGF-like domain of the extracellular domain of HRGβ1 while others used bacterially-expressed HRGβ1. Our in vitro data demonstrated that the full-length extracellular domain of human HRGβ1 reduced clonal growth of MDA-MB-435 breast cancer cells but stimulated apoptosis in MDA-MB-435 and MCF-7 breast cancer cells. In addition, mammalian-expressed HRGβ1 did not dramatically affect matrix metalloproteinase-9 activity but did inhibit cell motility of MDA-MB-435 and MCF-7 cells. Taken together, the in vitro data indicated that HRGβ1 inhibits metastasis-associated properties. ^ The in vivo data demonstrated that inducible expression of the full-length extracellular domain of human HRGβ1 in MDA-MB-435 cells reduced tumor volume and cell proliferation but increased apoptosis of cells injected at the mammary fat pad in nude mice. More importantly, HRGβ1 reduced the number of metastases observed by a spontaneous metastasis assay. Taken together, these data indicate that the full-length extracellular domain of human HRGβ1 has the net effect of inhibiting breast cancer metastasis. ^

Head and Neck Embryology: An Overview of Development, Growth and Defect in the Human Fetus

The purpose of this research is to explore the growth and formation of the head and neck from embryological development through puberty in order to understand how this knowledge is necessary for the development of dental and medical treatments and procedures. This is a necessary aspect of the medical and dental school curriculum at the University of Connecticut Health Center Schools of Medicine and Dental Medicine that needs to be incorporated into the current study of embryology for first-year students. Working with Dr. Christine Niekrash, D.M.D, this paper will cover the embryology and growth of the head, face and oral cavity. The goal of this project will be to organize the information and recognize the resources needed to successfully introduce this part of human physiology to the UConn dental and medical students. One area in which this information is particularly relevant is the facial and oral deformities that can occur throughout fetal development.

Cool-season turfgrass color and growth calibrated to leaf nitrogen

Tissue N analysis a tool available for N management of turfgrass. However, peer-reviewed calibration studies to determine optimum tissue N values are lacking. A field experiment with a mixed cool-season species lawn and a greenhouse experiment with Kentucky bluegrass (Poa pratensis L.) were conducted across 2 yr, each with randomized complete block design. Treatments were N application rates between 0 and 587 kg N ha-1 yr-1. In the field experiment, clipping samples were taken monthly from May to September, dried, ground, and analyzed for total N. Clippings samples were collected one to two mowings after plots were fertilized. Linear plateau models comparing relative clipping yield, Commission Internationale de l' Eclairage hue, and CM1000 index to leaf N concentrations were developed. In the greenhouse experiment, clipping samples were taken every 2 wk from May to October and composited across sample dates for leaf N analysis. Color and clipping yields were related to leaf N concentrations using linear plateau models. These models indicated small marginal improvements in growth or color when leaf N exceeded 30 g kg-1, suggesting that a leaf N test can separate turf with optimum leaf N concentrations from turf with below optimum leaf N concentrations. Plateaus in leaf N concentrations with increasing N fertilizer rates suggest, however, that this test may be unable to identify sites with excess available soil N when turf has been mowed before tissue sampling.

Productivity Growth and Efficiency in Indian Banking: A Comparison of Public, Private, and Foreign Banks

India's public sector banks (PSBs) are compared unfavorably with their private sector counterparts, domestic and foreign. This comparison rests, for the most part, on financial measures of performance, and such a comparison provides much of the rationale for privatization of PSBs.In this paper, we attempt a comparison between PSBs and their private sector counterparts based on measures of productivity that use quantities of outputs and inputs. We employ two measures of productivity: Tornqvist and Malmquist total factor productivity growth. We attempt these comparisons over the period 1992-2000, comparing PSBs with both domestic private and foreign banks. Out of a total of four comparisons we have made, there are no differences in three cases, PSBs do better in two, and foreign banks in one. To put it differently, PSBs are seen to be at a disadvantage in only one out of six comparisons. It is difficult, therefore, to sustain the proposition that efficiency and productivity have been lower in public sector banks relative to their peers in the private sector.

Cross-Country Evidence on Output Growth Volatility: Nonstationary Variance and GARCH Models

This paper revisits the issue of conditional volatility in real GDP growth rates for Canada, Japan, the United Kingdom, and the United States. Previous studies find high persistence in the volatility. This paper shows that this finding largely reflects a nonstationary variance. Output growth in the four countries became noticeably less volatile over the past few decades. In this paper, we employ the modified ICSS algorithm to detect structural change in the unconditional variance of output growth. One structural break exists in each of the four countries. We then use generalized autoregressive conditional heteroskedasticity (GARCH) specifications modeling output growth and its volatility with and without the break in volatility. The evidence shows that the time-varying variance falls sharply in Canada, Japan, and the U.K. and disappears in the U.S., excess kurtosis vanishes in Canada, Japan, and the U.S. and drops substantially in the U.K., once we incorporate the break in the variance equation of output for the four countries. That is, the integrated GARCH (IGARCH) effect proves spurious and the GARCH model demonstrates misspecification, if researchers neglect a nonstationary unconditional variance.

Technology Creation, Diffusion, and Growth Cycles

Standard macroeconomic models that assume an exogenous stochastic process for multifactor productivity offer the interpretation that recessions are the result of ''bad news'' (technological regress) and expansions are the result of ''good news'' (technological advancement). The view taken here is that both expansions and recessions are the result of ''good news'' in the sense that in both cases, aggregate production possibilities have increased. Recessions can be thought of as the transition from one technological frontier to the next.

An overview of China's one child policy and health consequences on society

In 1979, China implemented the one child policy to stifle the burden of the massive demographic growth cast on the future economic development and quality of living conditions. At the time, a quarter of the world's population resided in China and occupied only 7 percent of the world's arable land (The World Factbook, 2006). The government set the target total population to about 1.4 billion for the year 2010 and to significantly reduce the natural increase rate. First this overview paper will describe population demographics and economy of China's society. This paper will also investigate what the one child policy entails and how it is implemented. Furthermore, the consequences of the policy in regard to population growth, sex ratio, marital discrepancies, adverse health of mother and child, aging population, and pension coverage will be examined. Finally, future recommendations and an alternative policy will be postulated to increase the effectiveness of the policy and improve its effects on health. ^

NRAS and BRAF mutations in primary cutaneous melanoma: A comparison of mutation rates between radial and vertical growth phases in individual tumors

Primary cutaneous melanoma is a cancer arising from melanocytes in the skin. In recent decades the incidence of this malignancy has increased significantly. Mortality rates are high for patients with tumors measuring over a few millimeters in thickness. Response rates to conventional radiation and chemotherapy are very low in patients with metastatic melanoma. New therapies targeting melanoma’s aberrant cell signaling pathways such as the MAP Kinase pathway are being developed. Mutations of NRAS and BRAF genes are quite common in cutaneous melanoma and lead to constitutive activation of the MAP Kinase pathway. This study tests the hypothesis that NRAS and BRAF mutations increase as a tumor progresses from the noninvasive radial growth phase (RGP) to the invasive vertical growth phase (VGP). Laser capture microdissection was used to obtain separate, pure tumor DNA samples from the RGP and VGP of thirty primary cutaneous melanomas. PCR was used to amplify NRAS exon 2 and BRAF exon 15 tumor DNA. The amplified DNA was sequenced and analyzed for mutations. An overall mutation rate of 74% was obtained for the twenty-three melanomas in which there were complete sequence results. With the exception of one melanoma NRAS and BRAF mutations were mutually exclusive. All seven NRAS exon 2 mutations involved codon 61. Three of these melanomas had mutations in both the RGP and VGP. The remaining four tumors were wild type for NRAS exon 2 in the RGP but mutated in the VGP. Of the fifteen BRAF exon 15 mutated melanomas all but one involved codon 600. Twelve of the fifteen BRAF exon 15 mutations were the T1799A type. Nine of the fifteen BRAF mutated tumors had the same mutation in both the RGP and VGP. Five of fifteen melanomas had wild type RGP DNA and BRAF exon 15 mutated VGP DNA. A single melanoma had BRAF exon 15 mutated DNA in the RGP and wild type DNA in the VGP. Overall, these results suggest a trend toward the acquisition of NRAS and BRAF mutations as cutaneous melanomas change from a noninvasive to an invasive, potentially deadly cancer.^

Growth and development of body fat distribution from skinfold measurements: Longitudinal principal components

Longitudinal principal components analyses on a combination of four subcutaneous skinfolds (biceps, triceps, subscapular and suprailiac) were performed using data from the London Longitudinal Growth Study. The main objectives were to discover at what age during growth sex differences in body fat distribution occur and to see if there is continuity in body fatness and body fat distribution from childhood into the adult status (18 years). The analyses were done for four age sectors (3mon-3yrs, 3yrs-8yrs, 8yrs-18yrs and 3yrs-18yrs). Longitudinal principal component one (LPC1) for each age interval in both sexes represents the population mean fat curve. Component two (LPC2) is a velocity of fatness component. Component three (LPC3) in the 3mon-3yrs age sector represents infant fat wave in both sexes. In the next two age sectors component three in males represents peaks and shifts in fat growth (change in velocity), while in females it represents body fat distribution. Component four (LPC4) in the same two age sectors is a reversal in the sexes of the patterns seen for component three, i.e., in males it is body fat distribution and in females velocity shifts. Components five and above represent more complicated patterns of change (multiple increases and decreases across the age interval). In both sexes there is strong tracking in fatness from middle childhood to adolescence. In males only there is also a low to moderate tracking of infant fat with middle to late childhood fat. These data are strongly supported in the literature. Several factors are known to predict adult fatness among the most important being previous levels of fatness (at earlier ages) and the age at rebound. In addition we found that the velocity of fat change in middle childhood was highly predictive of later fatness (r $\approx -$0.7), even more so than age at rebound (r $\approx -$0.5). In contrast to fatness (LPC1), body fat distribution (LPC3-LPC4) did not track well even though significant components of body fat distribution occur at each age. Tracking of body fat distribution was higher in females than males. Sex differences in body fat distribution are non existent. Some sex differences are evident with the peripheral-to-central ratios after age 14 years. ^

SEVERITY OF IRON DEFICIENCY ANEMIA AND ITS RELATIONSHIP TO GROWTH AND MORBIDITY IN A POPULATION OF PRE-SCHOOLERS IN RURAL GUATEMALA (IRON DEFICIENCY, MORBIDITY, GROWTH)

The objectives of this study were to determine the nature of the relationship between severity of iron deficiency anemia, response to iron treatment, respiratory and gastrointestinal illness and weight change. Seventy-five pre-school children from rural Guatemala received daily oral iron therapy for an eleven week period, and were classified into one of three groups having different degrees of iron deficiency anemia. Anthropometric and biochemical data were collected prior and after iron treatment; morbidity data were collected throughout the period of treatment. The outcome variables were percentage weight change, percentage of total days ill with any type of symptom, percentage of total days ill with gastrointestinal symptoms, percentage of total days ill with respiratory symptoms, percentage of total days ill with combination syndrome symptoms. Age, sex and socio-economic status, were independent of any of the independent or outcome variables used. On the other hand, the level of hemoglobin covaried with the height of the children, the smallest children were the most severely anemic. The relationships between hemoglobin levels and weight change, frequency of morbidity (gastrointestinal, respiratory and combination syndrome) and total number of days ill with any symptomatology were investigated. No statistical significance was found in these analyses except when contrasting children with normal hemoglobin levels to iron deficient children, where the findings indicated the normal children experienced more gastrointestinal morbidity. The same relationship were again analyzed but including delta hemoglobin as covariate in the analysis, this latter one was found to be significant at 7% when the percentage of days ill from gastrointestinal morbidity was tested against the hemoglobin groups. The relationship found indicates that, all other covariates accounted for, the percentage of days ill from gastrointestinal morbidity will decrease approximately 1% for each 1% increase in delta of hemoglobin. ^

Robust effect sizes and their confidence intervals for group difference between trajectories in hierarchical linear growth model

Hierarchical linear growth model (HLGM), as a flexible and powerful analytic method, has played an increased important role in psychology, public health and medical sciences in recent decades. Mostly, researchers who conduct HLGM are interested in the treatment effect on individual trajectories, which can be indicated by the cross-level interaction effects. However, the statistical hypothesis test for the effect of cross-level interaction in HLGM only show us whether there is a significant group difference in the average rate of change, rate of acceleration or higher polynomial effect; it fails to convey information about the magnitude of the difference between the group trajectories at specific time point. Thus, reporting and interpreting effect sizes have been increased emphases in HLGM in recent years, due to the limitations and increased criticisms for statistical hypothesis testing. However, most researchers fail to report these model-implied effect sizes for group trajectories comparison and their corresponding confidence intervals in HLGM analysis, since lack of appropriate and standard functions to estimate effect sizes associated with the model-implied difference between grouping trajectories in HLGM, and also lack of computing packages in the popular statistical software to automatically calculate them. ^ The present project is the first to establish the appropriate computing functions to assess the standard difference between grouping trajectories in HLGM. We proposed the two functions to estimate effect sizes on model-based grouping trajectories difference at specific time, we also suggested the robust effect sizes to reduce the bias of estimated effect sizes. Then, we applied the proposed functions to estimate the population effect sizes (d ) and robust effect sizes (du) on the cross-level interaction in HLGM by using the three simulated datasets, and also we compared the three methods of constructing confidence intervals around d and du recommended the best one for application. At the end, we constructed 95% confidence intervals with the suitable method for the effect sizes what we obtained with the three simulated datasets. ^ The effect sizes between grouping trajectories for the three simulated longitudinal datasets indicated that even though the statistical hypothesis test shows no significant difference between grouping trajectories, effect sizes between these grouping trajectories can still be large at some time points. Therefore, effect sizes between grouping trajectories in HLGM analysis provide us additional and meaningful information to assess group effect on individual trajectories. In addition, we also compared the three methods to construct 95% confident intervals around corresponding effect sizes in this project, which handled with the uncertainty of effect sizes to population parameter. We suggested the noncentral t-distribution based method when the assumptions held, and the bootstrap bias-corrected and accelerated method when the assumptions are not met.^