Impact of renal function and protein intake on blood urea nitrogen in preterm infants in the first 3 weeks of life

OBJECTIVE

To examine the relationship between blood urea nitrogen (BUN) during the first 3 weeks of life and protein intake and creatinine (Cr) and to quantify the effect of protein intake on postnatal growth in preterm infants.

STUDY DESIGN

This is a 4-year, single-center, retrospective cohort study. We used multivariable linear regression models to examine the relationships between mean weekly BUN and protein intake adjusted for mean weekly Cr and potential confounders. We used additional regression models to examine the effect of protein intake on growth during this period.

RESULT

Overall, 249 infants met study criteria. As protein intake increased over the first 3 weeks of life, both BUN and Cr decreased significantly. Linear regression models showed protein intake and Cr were each significantly associated with mean BUN for each study week.

CONCLUSION

Protein intake and Cr were each significantly associated with BUN. Significant amelioration of growth failure was seen with higher protein intake.

Molecular insights into the coding region determinant-binding protein-RNA interaction through site-directed mutagenesis in the heterogeneous nuclear ribonucleoprotein-K-homology domains

The ability of its four heterogeneous nuclear RNP-K-homology (KH) domains to physically associate with oncogenic mRNAs is a major criterion for the function of the coding region determinant-binding protein (CRD-BP). However, the particular RNA-binding role of each of the KH domains remains largely unresolved. Here, we mutated the first glycine to an aspartate in the universally conserved GXXG motif of the KH domain as an approach to investigate their role. Our results show that mutation of a single GXXG motif generally had no effect on binding, but the mutation in any two KH domains, with the exception of the combination of KH3 and KH4 domains, completely abrogated RNA binding in vitro and significantly retarded granule formation in zebrafish embryos, suggesting that any combination of at least two KH domains cooperate in tandem to bind RNA efficiently. Interestingly, we found that any single point mutation in one of the four KH domains significantly impacted CRD-BP binding to mRNAs in HeLa cells, suggesting that the dynamics of the CRD-BP-mRNA interaction vary over time in vivo. Furthermore, our results suggest that different mRNAs bind preferentially to distinct CRD-BP KH domains. The novel insights revealed in this study have important implications on the understanding of the oncogenic mechanism of CRD-BP as well as in the future design of inhibitors against CRD-BP function.

Reviewing HIV-Related Research in Emerging Economies: The Role of Government Reviewing Agencies

Little research has explored the possible effects of government institutions in emerging economies on ethical reviews of multinational research. We conducted semi-structured, in-depth telephone interviews with 15 researchers, Research Ethics Committees (RECs) personnel, and a government agency member involved in multinational HIV Prevention Trials Network (HPTN) research in emerging economies. Ministries of Health (MOH) or other government agencies often play pivotal roles as facilitators or barriers in the research ethics approval process. Government agency RECs reviewing protocols may face particular challenges, as they can lack resources, be poorly organized, have inconsistent review processes and limited expertise, and use differing definitions of national interests, including upholding national reputation and avoiding potential exploitation and stigma of the country's population. The MOH/governmental review body may be affected by power dynamics and politics in study reviews; may consider issues both related and unrelated to research ethics as understood elsewhere; and may prioritize particular diseases, treatments, or interventions over other topics/types of research. Poor communication and deeply-rooted tensions may exist between sponsor and host countries, impeding optimal interactions and reviews. Investigators must understand and plan for the potential effects of governmental agencies on multinational collaborative research, including preserving adequate time for agency review, and contacting these agencies beforehand to address issues that may arise. Better understanding of these issues can aid and advance appropriate global scientific collaboration.

Abstract 2338: Functional investigation of the CRD-BP hnRNP-K-Homology domains for C-myc messenger RNA interaction

The coding region determinant binding protein (CRD-BP) is an oncofetal protein, being ubiquitously expressed during embryogenesis, yet highly repressed in adult tissues, except in cancerous tissues [Bell et al, 2013; Mueller-Pillasch et al, 1999]. CRD-BP was inherently identified by its ability to physically associate with c-myc mRNA, and has been shown to protect the transcript from degradation, hence prolonging its mRNA half-life [Prokipcak et al, 1994, Noubissi et al, 2006]. In addition to c-myc mRNA, several other mRNAs bound by CRD-BP have gene products implicated in the development and progression of cancer [Bell et al, 2013]. As an RNA binding protein (RBP), CRD-BP is the Mus musculus variant and homologous to the Homo sapiens IMP-1/Insulin-Like Growth Factor 2 with 99.31% similarity, both categorized into a larger family named VICKZ (Vera/Vg1 RBP, Insulin-Like Growth Factor 1,2,3/IMP-1,2,3, CRD-BP, KOC, and ZBP-1). The VICKZ family of RBPs contains two RNA Recognition Motifs (RRM) and four heterogeneous nuclear ribonucleoprotein [hnRNP]-K-Homology (KH) domains. Deletion analysis had shown that the KH domains, and not the RRM domains, of IMP1 are important for binding RNA substrates. To understand which of the KH domains are critical for interaction with RNA, site-directed mutagenesis was performed to introduce an aspartic acid (D) at the first glycine (G) of the G-X-X-G region in the KH domains of CRD-BP. This D-X-X-G variation was individually introduced to the four KH domains of CRD-BP. These four CRD-BP KH domain variants were expressed, purified and assessed for ability to bind c-myc mRNA using electromobility shift assays (EMSA). In addition, plasmids carrying these variants of FLAG-CRD-BP were transfected into HeLa cells. Immunoprecipitation (IP) using anti-FLAG was performed, followed by RT-qPCR to measure the relative amounts of c-myc mRNA associated with each of the variants as compared to the controls. The in vitro EMSA and IP cell data were all consistent with the notion that all KH domain(s) are critical for CRD-BP-c-myc RNA interaction. Using EMSA, additional binding assessments were carried out in a systematic fashion to determine the smallest region of c-myc mRNA bound by CRD-BP. These results will be presented and discussed, as they provide insight into the role played by the KH domains of CRD-BP in binding RNA, as well as what RNA characteristics are important for binding to CRD-BP.

Citation Format: Gerrit van Rensburg, Mark Barnes, Chow Lee. Functional investigation of the CRD-BP hnRNP-K-Homology domains for C-myc messenger RNA interaction. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2338. doi:10.1158/1538-7445.AM2014-2338

Use of single- versus multiple-fraction palliative radiation therapy for bone metastases: population-based analysis of 16,898 courses in a Canadian province

PURPOSE

There is abundant evidence that a single fraction (SF) of palliative radiation therapy (RT) for bone metastases is equivalent to more protracted and costly multiple fraction courses. Despite this, there is low utilization of SFRT internationally. We sought to determine the utilization of SFRT in a population-based, publicly funded health care system.

METHODS AND MATERIALS

All consecutive patients with bone metastases treated with RT during 2007 to 2011 in British Columbia (BC) were identified. Associations between utilization of SFRT and patient and provider characteristics were investigated.

RESULTS

A total of 16,898 courses of RT were delivered to 8601 patients. SFRT was prescribed 49% of the time. There were positive relationships among SFRT utilization and primary tumor group (P<.001; most commonly in prostate cancer), worse prognosis (P<.001), increasing physician experience (P<.001), site of metastases (P<.001; least for spine metastases), and area of training (P<.001; most commonly for oncologists trained in the United Kingdom). There was wide variation in the prescription of SFRT across 5 regional cancer centers, ranging from 25.5% to 73.4%, which persisted after controlling for other, potentially confounding factors (P<.001).

CONCLUSIONS

The large variability in SFRT utilization across BC Cancer Agency (BCCA) cancer centers suggests there is a strong cultural effect, where physicians' use of SFRT is influenced by their colleagues' practice. SFRT use in BC was similar to that in other Canadian and western European reports but strikingly higher than in the United States. Further work is needed to standardize SFRT prescribing practices internationally for this common indication for RT, with the potential for huge health system cost savings and substantial improvements in patients' quality of life.

Kupffer cells in the liver

Kupffer cells are a critical component of the mononuclear phagocytic system and are central to both the hepatic and systemic response to pathogens. Kupffer cells are reemerging as critical mediators of both liver injury and repair. Kupffer cells exhibit a tremendous plasticity; depending on the local metabolic and immune environment, then can express a range of polarized phenotypes, from the proinflammatory M1 phenotype to the alternative/M2 phenotype. Multiple M2 phenotypes can be distinguished, each involved in the resolution of inflammation and wound healing. Here, we have provided an update on recent research that has contributed to the developing delineation of the contribution of Kupffer cells to different types of liver injury, with an emphasis on alcoholic and nonalcoholic liver diseases. These recent advances in our understanding of Kupffer cell function and regulation will likely provide new insights into the potential for therapeutic manipulation of Kupffer cells to promote the resolution of inflammation and enhance wound healing in liver disease.

Multiscale gyrokinetics for rotating tokamak plasmas: fluctuations, transport and energy flows

This paper presents a complete theoretical framework for studying turbulence and transport in rapidly rotating tokamak plasmas. The fundamental scale separations present in plasma turbulence are codified as an asymptotic expansion in the ratio ε = ρi/α of the gyroradius to the equilibrium scale length. Proceeding order by order in this expansion, a set of coupled multiscale equations is developed. They describe an instantaneous equilibrium, the fluctuations driven by gradients in the equilibrium quantities, and the transport-timescale evolution of mean profiles of these quantities driven by the interplay between the equilibrium and the fluctuations. The equilibrium distribution functions are local Maxwellians with each flux surface rotating toroidally as a rigid body. The magnetic equilibrium is obtained from the generalized Grad-Shafranov equation for a rotating plasma, determining the magnetic flux function from the mean pressure and velocity profiles of the plasma. The slow (resistive-timescale) evolution of the magnetic field is given by an evolution equation for the safety factor q. Large-scale deviations of the distribution function from a Maxwellian are given by neoclassical theory. The fluctuations are determined by the 'high-flow' gyrokinetic equation, from which we derive the governing principle for gyrokinetic turbulence in tokamaks: the conservation and local (in space) cascade of the free energy of the fluctuations (i.e. there is no turbulence spreading). Transport equations for the evolution of the mean density, temperature and flow velocity profiles are derived. These transport equations show how the neoclassical and fluctuating corrections to the equilibrium Maxwellian act back upon the mean profiles through fluxes and heating. The energy and entropy conservation laws for the mean profiles are derived from the transport equations. Total energy, thermal, kinetic and magnetic, is conserved and there is no net turbulent heating. Entropy is produced by the action of fluxes flattening gradients, Ohmic heating and the equilibration of interspecies temperature differences. This equilibration is found to include both turbulent and collisional contributions. Finally, this framework is condensed, in the low-Mach-number limit, to a more concise set of equations suitable for numerical implementation.

Intrinsic rotation driven by non-Maxwellian equilibria in Tokamak plasmas

The effect of small deviations from a Maxwellian equilibrium on turbulent momentum transport in tokamak plasmas is considered. These non-Maxwellian features, arising from diamagnetic effects, introduce a strong dependence of the radial flux of cocurrent toroidal angular momentum on collisionality: As the plasma goes from nearly collisionless to weakly collisional, the flux reverses direction from radially inward to outward. This indicates a collisionality-dependent transition from peaked to hollow rotation profiles, consistent with experimental observations of intrinsic rotation.