bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regulation of the Stoichiometry of the Human Selenocysteine Synthase (SepSecS) Catalytic Complex
Authors: Puppala Anupama K. , Simonovic Miljan 
Published: November 2023

Selenium is an essential micronutrient for human health. The biologically active form of selenium in all domains of life is the 21st amino acid, selenocysteine (Sec). The incorporation of Sec into proteins is unique compared to the standard amino acids as Sec is encoded by a UGA stop codon and directly synthesized from a serine precursor on its cognate tRNA, tRNASec. Although not well understood, Sec biosynthesis requires three unique enzymes in archaea and eukaryotes. The enzyme selenocysteine synthase (SepSecS) is a tetrameric enzyme that catalyzes the terminal reaction of Sec synthesis in which a phosphoseryl intermediate is converted into the selenocysteinyl moiety while attached to tRNASec. Our previous studies have demonstrated that human SepSecS, despite containing four equivalent tRNA‐binding sites and active‐site grooves, only binds one or two substrate molecules at a given time. Recent structural data have provided a potential explanation for this restriction on the stoichiometry of the SepSecS catalytic complex. High‐resolution electron density maps of the SepSecS‐tRNASec complex have revealed a previously unobserved α‐helix positioned in the potential tRNASec binding site of the noncatalytic subunits of the tetramer. This helix directly interacts with residues that are critical for tRNASec recognition and binding. Thus, the presence of this α‐helix precludes binding of an additional tRNASec molecule. This helix is disordered in the structure of the SepSecS holoenzyme, suggesting that in the tRNASec‐free state all four tRNASec binding sites are equally available for substrate binding. Our data suggest a model of allosteric regulation of SepSecS substrate binding in which binding of a single tRNASec molecule leads to a conformational change in the tetrameric enzyme that prevents binding at two of the four potential tRNASec binding sites.Support or Funding InformationThis work was supported by a grant from the National Institute of General Medical Sciences of the National Institutes of Health R01 GM097042.
Zinc and Copper Balances During Three Weeks of Bed Rest, With or Without an Artificial Gravity Countermeasure
Authors: Heacox Hayley Nicole , Smith Scott M. , Zwart Sara R. , Gillman Patricia L. 
Published: November 2023

Nutrition remains a key concern for extended‐duration space missions. Zinc and copper are trace minerals with many functions in the body, but both possess little to no storage capability. Zinc and copper balances were studied in 15 male subjects before, during, and after a 21‐d head‐down tilt bed rest study in which 8 participants were subjected to artificial gravity (AG) by centrifugation for 1 h/d. The study was conducted in a general clinical research center with carefully controlled dietary intake and collection of all urine and feces for subsequent analyses. Urine samples were analyzed for copper and zinc by inductively coupled plasma mass spectrometry using a NexION 350D ICP‐MS (Perkin Elmer, Shelton, CT) equipped with collision/reaction cell technology for interference removal. While energy intakes were adjusted to maintain subject mass, subjects in both control (CON) and AG‐treated groups had lower lean body mass after bed rest. Despite lower intake of both minerals during bed rest, both CON and AG subject groups had higher fecal and urinary zinc excretion during bed rest, with a resulting lower net balance of zinc. Urinary copper excretion did not change during bed rest but was higher after bed rest in the AG group. Fecal copper was higher during bed rest compared to pre‐bed rest. Copper balance was unaltered for the CON group but significantly decreased during and after bed rest for the AG group. The increased fecal excretion of these minerals during bed rest suggests that their absorption from the diet was reduced, secondary to the release of minerals from both bone and muscle tissue as zinc and copper are predominantly found in musculoskeletal tissues. These findings highlight the importance of determining nutrient requirements for astronauts on space missions and ensuring provision and intake of all nutrients as we explore beyond low Earth orbit.Support or Funding InformationThis study was funded by the NASA Human Research Program's Human Health Countermeasures Element. This study was conducted with the support of the Institute for Translational Sciences at the University of Texas Medical Branch, supported in part by a Clinical and Translational Science Award (UL1TR000071) from the National Center for Advancing Translational Sciences, National Institutes of Health. HH was supported by an Arkansas Space Grant Consortium Workforce Development Grant.
Changes in Blood Folate Concentrations in Response to Intake of Folic Acid – a Systematic Review and Meta‐analysis
Authors: Crider Krista S , Devine Owen , Qi Yan Ping , Yeung Lorriane , Sekkarie Ahila , Zaganjor Ibrahim , Berry Robert J 
Published: November 2023

BackgroundThe threshold for optimal red bloodcell (RBC) folate concentration for the prevention of neural tube defects wasset at 400ng/ml (906 nmol/L) by the World Health Organization (WHO) in 2015. After countries determine the distribution of RBC folate concentrations among reproductive age women, it will be critical to know how much additional folic acid intake from either a supplement or a fortification program is needed to reach the optimal concentrations specified in the WHO guideline. It is currently recommended that women consume 400 micrograms (mcg) of folic acid a day either through a supplement, fortified foods, or both.ObjectiveThe objective of this project was to determine how much blood folate concentrations increase in response to increasing doses of folic acid after three months of intake (as when taking a supplement) and then again after intake at steady state (similar to fortification).ResultsTo accomplish this we conducted a systematic review of the literature for studies that included a known dose of folic acid taken continuously for ≥28 days. We searched for publications in Medline, Embase, CINAHL, Cochrane Library, POPLINE, and ClinicalTrials.gov. Of the 13,682 abstracts reviewed, 516 were selected for full‐text review and data from 100 articles were abstracted. Using a Bayesian meta‐analytic approach, one‐compartment physiologically based pharmacokinetic(PBPK) models describing folate uptake and elimination were used to estimate the steady‐state concentrations of both serum and RBC folate levels at varying levels of folic acid supplementation. Preliminary estimates showed that at approximately 400 mcg folic acid/day, RBC folate concentration increased 85% [Uncertainty Interval:75%, 97%] at steady state (after more than about 30 weeks of intake).ConclusionsThese results suggest that at there commended intake of folic acid to prevent neural tube defects (400 mcg/day) at steady state, RBC folate concentrations almost double. Additional analyses are underway to determine the impact of different doses of folic acid on serum and RBC folate concentrations.
The Role of Lipocalin‐2 (Lcn2) in Acetaminophen Induced Acute Liver Failure
Authors: Paul Christina , Gajjar Nisha , Bhave Vishakha 
Published: November 2023

Acetaminophen (APAP) toxicity is the number one cause of acute liver failure, and treatment options are limited. The initial toxicity is caused by the bio‐activation of the drug to the reactive metabolite, N‐acetyl‐p‐benzoquinone imine (NAPQI). However, progression of injury still occurs even after all of the drug has been eliminated from the body. APAP overdose involves sterile inflammation. Lipocalin‐2 is an innate immune protein that is known to be up‐regulated in various disease models and has been observed to have a protective as well as destructive role dependent on the model analyzed. Studies have shown that Lcn2 acts as an anti‐inflammatory modulator in low doses of toxicity, when pro‐mitogenic signaling is activated. In contrast, these repair and regeneration pathways are shown to be inhibited in a high dose model of toxicity, which ultimately leads to acute liver failure. The role of Lcn2 in a high dose model of toxicity has not yet been investigated. This study aims to investigate the role of Lcn2 in drug induced acute liver failure (APAP overdose) model and the mechanism of its involvement. An in vivo model of acute liver failure will be utilized and Lcn2−/− mice will be used as our intervention. We hypothesize that Lcn2−/− mice will be protected from APAP induced acute liver failure. Time course studies will be done over a period of 0–96 hours post APAP overdose. Liver and serum will be harvested at each time point and extent of injury will be assessed via ALT/AST assays and H&E staining. Bio‐activation studies will be done to determine any differences in the metabolism of the drug between the treatment groups, which include protein adduct formation and glutathione depletion and replenishment. Pro‐ and anti‐inflammatory cytokines will be measured to elucidate the role of Lcn2 in mediating progression of injury. Proliferating cell nuclear antigen (Pcna) staining will be done as a marker of liver regeneration. Our preliminary data demonstrate 20% lethality in Lcn2−/− mice and 60% lethality in WT mice subjected to APAP overdose. In conclusion, the protection of Lcn2−/− mice from APAP overdose indicates that Lcn2 may play a role in mediating progression of injury. Further experiments will be done to elucidate the mechanism of action.Support or Funding InformationPhiladelphia College of Osteopathic Medicine‐Division of Research
Transcriptional Response in a Rat Model of Liver Ischemia‐Reperfusion Injury
Authors: Zabala Valerie , Thevenot Paul , Cohen Ari , Gruppuso Philip A. , Sanders Jennifer A. 
Published: November 2023

Ischemia‐reperfusion (I/R) is central to the pathophysiology of liver injury caused by acute hepatic traumas, including liver transplantation. Elevated levels of reactive oxygen species (ROS) govern the magnitude of liver injury and tissue damage. Therapies that reduce the ROS burden are under investigation to determine their ability to improve transplant outcomes including those associated with extended criteria donors. However, the pathways and upstream regulators that drive ROS‐mediated responses remain unknown. In this study, we have utilized a rodent model of 70% partial transient warm hepatic ischemia to characterize transcriptional changes in response to ischemic insult and during early reperfusion. Blood supply to the left and medial lobes was clamped for 30 minutes while the right lobes remain perfused. Animals were sacrificed at the end of ischemia (no reperfusion), and after thirty minutes or six hours of reperfusion. The ischemic lobes and the non‐ischemic lobes were each compared to tissue from animals that underwent sham surgery at each time. Total RNA was prepared for microarray and analyzed using Affymetrix Rat Transcriptome 1.0 arrays. Gene Set Enrichment Analysis (GSEA) and Ingenuity Pathway Analysis (IPA) of the 24,536 quantified genes revealed a great overlap in biological pathways and upstream regulators that changed in both the ischemic and non‐ischemic lobes when compared to shams. This implies a significant proportion of changes in the ischemic‐reperfused lobes were attributable to the effects of anesthesia and/or surgery. We found 1575 differentially expressed genes (FDR<0.05) in the ischemic‐reperfused group at 30 minutes and 2672 genes at 6 hours. However, 1067 and 1646 of the altered genes at 30 minutes and 6 hours, respectively, also changed in the non‐ischemic lobes, suggesting systemic factors play in role in the response to I/R. Among those genes unique to the ischemic‐reperfused group at thirty minutes, the expression of several immediate early genes (Egr‐1, Fos‐b, Jun‐b) increased over five‐fold. This response could indicate that induction of AP‐1 (activator protein‐1) in response to hypoxia plays a role in promoting cell survival. Further investigation of AP‐1 activity may identify new pharmacological targets to decrease hepatic ischemia‐reperfusion injury. This immediate early gene response, which is characteristic of liver regeneration after partial hepatectomy, has not been previously identified in models of hepatic ischemia‐reperfusion.Support or Funding InformationThis work was supported by NIGMS grant 5T32GM077995 from the National Institutes of Health, a Pharmacia Predoctoral Fellowship, and the Graduate Research Fellowship Program of the National Science Foundation (NSF).Valerie Zabala is a Howard Hughes Medical Institute Gilliam Fellow.
Leukocyte Specific Protein‐1 (LSP1) Functions as a Suppressor of Proliferation During Liver Regeneration After Partial Hepatectomy (PHx) and in Primary Hepatocytes
Authors: Koral Kelly , Bowen William , Haynes Meagan , Mars Wendy , Michalopoulos George 
Published: November 2023

Leukocyte specific protein‐1 (LSP1), an f‐actin binding protein expressed in hematopoietic cells and hepatocytes, is the gene with the highest copy number variation in human hepatocellular carcinoma. Our previous work has demonstrated that loss of LSP1 expression leads to increased proliferation and migration of rat hepatocellular carcinoma cells. We have also demonstrated that overexpression of LSP1 in mouse liver through hydrodynamic tail vein injection of LSP1 plasmid DNA results in a significant decrease in proliferation on day 2 after partial hepatectomy (PHx). To further characterize the role of LSP1 in liver regeneration, we performed 2/3 PHx on both a global LSP1 knockout mouse as well as a hepatocyte specific LSP1 transgenic mouse model and analyzed proliferation using ki67 immunohistochemistry as well as western blot analysis of ERK signaling. Since expression of LSP1 leads to decreased proliferation, we hypothesized that the knockout mouse model would exhibit increased proliferation and activation of ERK whereas the transgenic mouse model would display decreased proliferation and pERK expression. LSP1 knockout mice displayed an increase in Ki67 labeling on day 4 after PHx and western blot analysis shows increased pERK expression after PHx in comparison to controls. In the transgenic mouse model, a significant decrease in Ki67 positive hepatocytes was observed on day 4 after PHx as well as decreased pERK expression. Transgenic mice also displayed decreased liver to body weight ratios on day 7 following PHx. Hepatocytes isolated from knockout mice exhibited increased proliferation in the absence of growth factors compared to controls whereas transgenic mouse hepatocytes displayed decreased BrdU incorporation in both the presence and absence of growth factors. LSP1 knockout hepatocytes and transgenic hepatocytes also displayed increased and decreased pERK expression, respectively. Our results demonstrate that LSP1 functions as an inhibitor of proliferation in primary hepatocytes as well as during liver regeneration following PHx. Future studies aim to address the signaling pathways downstream of LSP1 that effect proliferation during liver regeneration as well as how LSP1 functions in hepatocarcinogenesis mechanisms and sensitivity to sorafenib.Support or Funding InformationMenten Endowment, University of Pittsburgh
Mice Lacking Liver‐Specific [beta]‐Catenin Develoop Steatohepatitis and Fibrosis After Iron Overload
Authors: Preziosi Morgan , Singh Sucha , Valore Erika , Jung Chun‐Ling , Nagarajan Shan , Ganz Tom , Monga Satdarshan 
Published: November 2023

Background & aimsIron overload disorders such as hereditary hemochromatosis and iron‐loading anemias are a common cause of morbidity from liver diseases and are risk factors for hepatic fibrosis and hepatocellular carcinoma (HCC). Once iron‐induced damage occurs, treatment options are limited, partly because of the lack of animal models recapitulating human disease, since mice do not exhibit fibrosis or HCC following chronic iron overload.MethodsA high iron containing diet was fed to normal mice to assess any effect on Wnt signaling. Iron overload diet was also administered to liver‐specific β‐catenin knockout (KO) and control (CON) mice for three months. To ameliorate an oxidant‐mediated component of tissue injury, N‐Acetyl‐L‐(+)‐cysteine (NAC) was added to drinking water of mice on iron overload diet.ResultsKO on iron diet (KO+Fe) exhibited remarkable steatosis, inflammation, hepatic fibrosis, regenerating nodules, and sequelae associated with increased oxidative stress. We also noted increased activation of AKT and NFkB pathways in KO+Fe. Addition of NAC to drinking water protected KO+Fe from hepatic steatosis, injury and fibrosis, and suppressed phosphorylation of AKT and NFkB.ConclusionsWe provide evidence that lack of hepatic b‐catenin predisposes mice to hepatic injury and fibrosis following iron overload thus phenocopying disease in patients. This is chiefly due to lack of antioxidant response in the absence of b‐catenin demonstrating its role in hepatic redox homeostasis. Lastly, antioxidant therapy may have a chemopreventive role in the management of chronic iron overload.
Proteomic Analysis of Focal Lesions in a Rat Model of Progenitor Marker‐Positive Hepatocellular Carcinoma
Authors: Michael Adeola O Adebayo , Ahsan Nagib , Francois‐Vaughan Heather , Zabala Valerie , Post Stephanie , Brilliant Kate E , Salomon Art , Gruppuso Philip , Sanders Jennifer A 
Published: November 2023

We have shown previously that rapamycin, the canonical inhibitor of the mechanistic target of rapamycin (mTOR), markedly inhibits the growth of focal lesions in the resistant hepatocyte (Solt‐Farber) model of HCC in the rat. In the present study, we characterized the proteome of persistent, pre‐neoplastic focal lesions in rats subjected to the Solt‐Farber protocol. One group was administered rapamycin by subcutaneous pellet for 3 weeks following partial hepatectomy and sacrificed 4 weeks after the cessation of rapamycin. A second group received placebo pellets. Results were compared to animals that underwent a protocol to activate hepatic progenitor cells. Normal rat liver was used as an additional control. Regions of formalin‐fixed, paraffin‐embedded tissue were obtained by laser capture microdissection. Peptides were generated and analyzed by liquid chromatography‐tandem mass spectrometry (LC‐MS/MS), which yielded 11,070 unique peptides representing 2,227 proteins. Peptides that showed increased abundance in placebo foci represented known HCC markers (glutathione S‐transferase‐P, epoxide hydrolase, 6 others) and potential markers (aflatoxin aldehyde reductase, carbonic anhydrase 2, 11 others). Peptides derived from cytochrome P450 enzymes were generally reduced. Neither placebo nor rapamycin samples showed similarity with the progenitor cell samples, indicating that the foci in this model, while considered to be progenitor marker‐positive, do not show evidence of persistent progenitor cells. Pathway analysis, based on non‐parametric identification of affected peptides, was consistent with an effect of rapamycin to reduce dedifferentiation in foci. Finally, we have demonstrated that the combination of LCM and LC‐MS/MS is an effective approach to characterize focal liver lesions.Support or Funding InformationNIH R01DK100301 NIH R01HD024455Rhode Island Hospital Department of Pediatrics
Analysis of Thermography and Breast Cancer Prevention Among Minority Women and Other Ethnic Groups
Authors: New Katina M , Einstein George P , Tulp Orien L 
Published: November 2023

Breast cancer is often a devastating disease that affects millions of women, regardless of race, ethnic group or socioeconomic status annually. The goal of this research is to demonstrate the high‐risk breast patterns as detected via Infrared Thermography and how the thermographic patterns can be improved with lifestyle and other changes, thereby decreasing the individual's risk for developing late stage breast cancer. Results of data obtained from fifteen women who underwent breast thermography, via a digital infrared imaging camera called the FLIR T420 were compared via t‐test. The goal of the study was to stratify patients on the scale of fibrocystic or precancerous breasts into none, mild, moderate and severe categories, and to identify high risk, moderate risk, and low risk groups based on a risk assessment questionnaire, blood tests for vitamin D 25‐OH, and testing for genetic mutation of the Methylenetetrahydrofolate reductase [MTHFR] gene. From this risk stratification we then determined the need for incorporating a prevention protocol which included: 1] education on diet, 2] exercise and prevention of exposure, 3] detoxification of environmental toxins; 4] education on stress relief; 5] education on breast self‐examination; 6] iodine and vitamin D supplementation; and 7] local application of Frankincense oil to the breast to help attenuate inflammatory processes. Patients were re‐evaluated after the initial exam at intervals of three months, six months and one year. This follow up monitored the benefits of the protocol and documented the progression of decrease in high risk factors for each patient. All 15 participants complied with all treatment regimens throughout the study. Participants exhibited marked improvements in breast health at the conclusion of the study. The results of this study indicate that beast examination via therrmography is effective in the aid of breast cancer prevention. These results indicate that thermography is an effective tool that should be utilized more by physicians and other health care providers to assist with early detection and prevention of breast cancer. Also, the results of this study support the encouragement of routine exercise, maintaining a BMI less than 30 and strategies that assist in stress management. Early MTHFR genetic testing will also help determine if the patient is at an increased risk for developing breast cancer prior to the onset of symptoms.Support or Funding InformationSupported by Institutional Resources of USAT and Einstein Medical Institute.