bluuebunny/crossref_metadata_2025_split huggingface dataset:
Expression of IGF‐1a and change in muscle fiber area after 12 weeks of resistance training in elderly postoperative patients
Authors: Suetta Charlotte , Clemmensen Christoffer , Andersen Jesper L , Magnusson S. Peter , Schjerling Peter , Kjaer Michael 
Published: June 2021

The mRNA splice variant of insulin‐like growth factor‐1a and the changes in muscle fiber cross sectional area after 12 weeks of rehabilitation, were studied in elderly postoperative patients. 28 subjects (age 60–86 yrs) were randomized to either resistance training (RT: 3/wk·12 wks), electrical stimulation (ES: 1 h/day·12 wks) or functional exercises (FE: 1 h/day·12 wks). Muscle biopsies were obtained from vastus lateralis (VL) of both legs at baseline, 5 and 12 wks post‐surgery to analyze for changes in mean muscle fiber area (MFA). Expression levels of IGF‐1a mRNA were determined using real‐time RT‐PCR and normalized to the Ribosomal Protein Large P0 (RPLP0) mRNA. There was no difference in MFA or resting levels of IGF‐1a between the three groups at baseline. RT resulted in a significant increase in IGF‐1a (+131 %, p<0.05) and MFA (+37%, p<0.05). In contrast, 12 weeks of ES and FE did not induce any change in MFA or in the expression of IGF‐1a. The present study is the first to demonstrate that resistance training initiated in the acute (1–2 days) postoperative phase is highly effective in increasing mean fiber area and in addition induced a marked increase in the expression of IGF‐1, supporting the idea that IGF‐1a may be involved in regulating muscle hypertrophy.Funded by the IMK Foundation and the Maersk McKinney Moller Foundation
Effect of fasting on resting and diving metabolic rate in Steller sea lions (Eumetopias jubatus)
Authors: Svärd Caroline Elisabeth , Fahlman Andreas , Joy Ruth , Rosen Dave , Trites Andrew 
Published: June 2021

The metabolic trade off between thermoregulation and fasting was assessed for foraging Steller sea lions. Pre‐dive resting (RMR) and diving (dive + surface) metabolic rates (DMR, 1 O2 · min−1) were measured for dives ranging between 20 to 50 m in 3 female Steller sea lions (mean initial body masses, Mb: 144.3, 167.4 and 219.9 kg) before and after a 9‐day fast. The sea lions lost an average of 9.8 % of their body mass (Mb) or 1.1 % per day. Dive duration and dive depth did not significantly affect DMR (p > 0.1). Average RMR and DMR before fasting ranged between 0.71 and 1.98 O2 • min−1 and was positively correlated with Mb (r2 = 0.97, p < 0.05). Both RMR (36.3 ± 5.22 %) and DMR (14.2 ± 12.3 %) decreased after fasting. The smaller decrease in DMR compared to RMR indicates that the cost of thermoregulation increased during diving compared to resting. RMR tended to increase in fasted sea lions within 1 hour of feeding, but was not observed in fed sea lions (p = 0.07). This suggests that digestion of food started while diving and had a greater energetic priority than dive performance in fasted animals.(Support: North Pacific Marine Science Foundation and NOAA; SC supported by a graduate student grant from the Swedish Government and by travel funds from SEB).
Selenoprotein N and Oxidative Stress: Characterisation of the role of a novel selenoprotein
Authors: Arbogast Sandrine , Ferreiro Ana 
Published: June 2021

Mutations of the selenoprotein N gene (SEPN1) have been identified as responsible for SEPN‐related myopathy (SEPN‐RM), an early‐onset muscle disorder. Selenoprotein N is the only selenoprotein implicated in a human genetic disorder but its function remained unknown. SelN has structural similarities with other selenoproteins which are involved in redox homeostasis. Therefore, we hypothesized that 1/ SelN depletion increase intracellular oxidant activity in cells, 2/ SelN plays a role in defence against oxidative stress. To verify this, we used human primary myoblasts and fibroblasts cultures from controls and patients carrying nonsense SEPN1 mutations. We measured intracellular oxidant activity using the DCFH assay. Furthermore, we examined the susceptibility of the cells to a wide range of H2O2 concentrations.Myoblasts devoid of SelN show a significant increase in intracellular oxidant activity compared to controls whereas fibroblasts do not. However, fibroblasts devoid of SelN are more sensitive to H2O2 ‐induced oxidative stress than normal fibroblasts, as evidenced by a significantly greater cell death. Furthermore, pre‐treatment with the antioxidant N‐acetyl cysteine restores cell survival against H2O2 to a level comparable to controls.This study establishes for the first time that oxidative stress is implicated in SEPN‐RM and that SelN protects human cells against oxidative stress.
Effect of photobiomodulation on glutathione redox status of gastrocnemius muscle in an animal model of diabetes
Authors: Lark Daniel Stephen , Gopalakrishnan Sandeep , Wilson Robert W , Sandoval Christopher L , Eells Janis T , Snyder Ann C 
Published: June 2021

INTRODUCTION: Glutathione (GSH) is an inter‐ and intra‐cellular antioxidant, and is essential in reducing reactive oxygen species (ROS) to prevent cellular damage. Photobiomodulation using 670 nm light has been shown to reduce oxidative damage in several animal models of degenerative disease. PURPOSE: To investigate the effects of photobiomodulation on the GSH redox status in the white (WG) and red gastrocnemius (RG) muscles of the streptozotocin (STZ) type I diabetic rat model. METHODS: Male Wistar rats (n = 26) were used in this study. Rats (n = 16) were injected with 50mg/kg (ip) of STZ and one group of STZ rats were exposed to 670 nm light for 5 minutes/day (6 J/cm2) for seventeen days (NIR‐STZ = 8). On day 18, animals were euthanized and gastrocnemius muscles were rapidly dissected and flash frozen. Glutathione was measured using an enzymatic recycling reaction developed by Cayman Chemicals. RESULTS: In response to STZ‐induced acute hyperglycemia, muscle GSH concentrations (total, oxidized and reduced) were increased. In contrast muscle GSH concentrations (total, oxidized and reduced) in 670 nm LED treated animals were nearly identical to control values. CONCLUSIONS: Although these changes were not statistically significant, these data suggest that photobiomodulation may be beneficial in modulating redox status of skeletal muscle in diabetes.Funding Source: Biomedical Technology Alliance Award and UWM Research Growth Initiative
Inhibition of capacitative calcium entry suppresses ouabain‐induced stimulation of sodium‐hydrogen exchange in rat optic nerve astrocytes
Authors: Mandal Amritlal , Shahidullah Mohammad , Delamere Nicholas 
Published: June 2021

Objective: Earlier we showed that 1 μM ouabain increased capacitative calcium entry (CCE) but did not increase cell sodium1. Here we studied cytoplasmic pH recovery after an acid load in ouabain‐treated cells and tested whether pH response were linked to altered calcium entry.Methods: Ammonium chloride (20mM) was used to acid load the cells. BCECF and FURA‐2 were used to measure intracellular pH and calcium.Results: Ammonium chloride removal causes the pHi to fall abruptly, followed by gradual recovery. lμM ouabain increased the rate of pHi recovery both in the presence and in the absence of bicarbonate in the bathing medium. NHE inhibitor DMA reduced the rate of pHi recovery. Ouabain did not detectably alter cytoplasmic Ca2+ (Ca2+i) but CCE inhibitors SKF96365 and 2APB reduced both the basal and ouabain‐stimulated rates of pHi recovery. Calcium chelator BAPTA‐AM also inhibited basal and ouabain‐stimulated pHi recovery. Western blot showed presence of NHE1 but not NHE2, NHE3 or NHE4.Conclusion: Ouabain‐induced stimulation of pHi recovery was due, at least in part, to stimulation of NHE1. Although lμM ouabain failed to alter Ca2+i, the findings suggest the NHE response may be dependent on CCE.Funding: NIH Grant EY014069
Discovery and Characterization of a novel DNA damage‐induced splice variant of Mdm2
Authors: Lents Nathan H , Dynlacht Brian David 
Published: June 2021

Mdm2, as the most important negative regulator of p53, plays an important homeostatic role in regulating cell division and the cellular response to DNA damage, oncogenic insult, and other forms of cellular stress. We discovered that the DNA damaging agent adriamycin (doxorubicin) induces a novel aberrantly spliced Mdm2 mRNA which incorporates 108bp of intronic sequence not normally found in the Mdm2 mature mRNA. Accordingly, we term this Mdm2 splice variant Mdm2+108. Importantly, this insertion introduces in‐frame nonsense codons, thus encoding a profoundly truncated mdm2 protein lacking the C‐terminal RING finger domain, E3 ubiquitin ligase activity, and p53‐binding site.A wide range of pharmacological testing revealed that Mdm2+108 is induced, in mouse and rat cells, in specific response to Adriamycin and actinomycin D, but not other modes of DNA damage. Meanwhile, antibodies against the N‐terminal region of mdm2 reveal a >90% reduction in detectable mdm2 protein upon Adriamycin treatment, while p53 accumulates to strikingly high levels. We thus conclude that this alternative spicing of Mdm2 may be an important mechanism to facilitate massive accumulation of p53 in response to genotoxic agents.
Adiponectin Repressed Proliferation of Colon Cancer Cells via AMPK Activation
Authors: Kim A Young , Lee Yun Sok , Choi Jin Woo , Kim Jae Bum 
Published: June 2021

Adiponectin is a member of adipocytockines and regulates whole body homeostasis. Recently, it has been shown that the level of plasma adiponectin is negatively correlated with the risk for certain cancers including breast, prostate, gastric, and colon cancers. However, it is largely unknown the role of adiponectin on colon cancers. In this work, we investigated the effects of adiponectin on the growth of colon cancer cells. Adiponectin specifically attenuated the growth of colon cancer cell lines, including HCT 116, HT‐29, and LoVo while it did not reduce the growth of normal cell lines such as HEK 293 and RWPE1. Consistently, adiponectin treatment into colon cancer cells enhanced the expression of CDK inhibitors including p21 and p27, indicating that adiponectin attenuates rapid growth of colon cancer cells by regulating of cell cycle. Moreover, adiponectin in colon cancer cells stimulated the activity of AMPK, which appears to be crucial to mediate suppression of cell growth. Collectively, our data suggest that adiponectin is a negative regulator of colon cancer growth, and that the growth inhibition effects of adiponectin on colon cancer cells might be dependent on AMPK activation.This work was supported in part by grants from the Molecular and Cellular BioDiscovery Research Program (M10748000258‐07N4800‐25810) and the National Research Laboratory Program (R0A‐2004‐000‐10359‐0) of Korea Science and Engineering Foundation (KOSEF). J.B.K. and A.Y.K. was supported by a BK21 Research Fellowship from the Ministry of Education and Human Resources Development.
Mitochondrial glycogen synthase kinase‐3beta: an investigation into its role in metabolism and cell fate
Authors: Clodfelder‐Miller Buffie J , King Taj D , Bijur Gautam N 
Published: June 2021

Glycogen synthase kinase‐3ß (GSK3ß) facilitates apoptosis signaling and also regulates cell metabolism. GSK3ß is mostly in the cytosol, but an active pool of GSK3ß is present in the mitochondria. The present study focuses on the unknown actions of GSK3ß in mitochondria. A novel strategy was employed using a lentivirus gene delivery to express an inducible mitochondrial‐targeted, active GSK3ß (mS9AGSK3ß) in neuroblastoma cells. Immunofluorescence microscopy confirmed that mS9AGSK3ß was specifically localized in mitochondria. Increased expression of mS9AGSK3ß by itself did not activate apoptosis. However, increased expression of mS9AGSK3ß significantly enhanced apoptosis and cell death when cells were cultured under conditions of reduced glycolysis. It was also found that mS9AGSK3ß expression greatly facilitated apoptosis induced by the oxidative phosphorylation complex I inhibitors MPP and rotenone, and inhibition of GSK3? activity with lithium blocked apoptosis. Thus, increased GSK3ß activity in the mitochondria is deleterious under conditions that increase mitochondrial function and during mitochondrial stress.Support by NARSAD, NIH‐NINDS, and the NIH Neuroscience Blueprint Core Grant NS57098.
An intramolecular binding site for the myristoylated amino‐terminus of Gαi
Authors: Preininger Anita M. , Meier Scott M. , Funk Michael A. , Iverson Tina M. , Hamm Heidi E. 
Published: June 2021

GPCRs act as guanine exchange factors for G‐proteins, catalyzing nucleotide release. The amino terminus of Gαi subunits is subject to reversible palmitoylation, as well as myristoylation, which is a permanent, co‐translational modification. Previous work has demonstrated that unmyristoylated Gαi proteins exhibit a disordered amino terminus in the absence of Gβγ, while myristoylated amino terminal residues are ordered even in the absence of Gβγ [Medkova, M. (2002) Biochemistry 41, 9963–9972; Preininger, A.M. (2003) Biochemistry 42, 7931–7941], suggesting an intramolecular binding site for the amino terminus of myristoylated Gαi subunits. In order to determine the location of this binding site, we utilized a combination of biophysical, biochemical and crystallographic methods. Using site‐directed‐mutagenesis combined with quenching studies, the extreme amino terminus undergoes activation‐dependent quenching by tryptophan residues within 15 Å of the extreme amino terminus, and this quenching occurs on the same timescale as that seen for nucleotide exchange. A crystal structure of a myristoylated Gαi protein demonstrates that myristoylation alters the conformation of Trp 258 (between the α‐3 helix and the β‐5 strand in the GTPase domain of Gαi proteins), and implicates this region as a participant in the intramolecular binding of the myristoylated amino terminus of Gαi proteins.This work was supported by the National Institutes of Health (Grant 2R01 EY06062‐22A2).
Inducing Cartilage Regeneration with Stem Cells for Treatment of Osteoarthritis Patients
Authors: Ferng Alice Shirong , Ferguson Christopher William , Szivek John A. 
Published: June 2021

Osteoarthritis is a progressive disease characterized by breakdown and loss of articular cartilage, which results in joint pain, stiffness, and limitations in activity and affects millions of people worldwide. Although artificial joint replacements are currently the gold standard for osteoarthritis patients, they can cause problems, such as bone loss, pain if the implant becomes loose, and a loss of proprioception.Stem cells converted to cartilage cells (chondrocytes) can be used to induce cartilage regeneration. Stem cells isolated from adipose (fat) tissue can differentiate into chondrocytes under the appropriate conditions (Guilak et al. (2003). Cytotherapy 5(5):362–9). This project investigates the chondrocytic potentials of human stem cell lines in vitro isolated from: 1) adipose tissue, 2) bone marrow, and 3) umbilical cord blood. Growth factors, TGF‐β3 and BMP‐6, known to encourage chondrogenesis of stem cells have been used to treat these stem cell lines. Additionally, a pilot study with canine adipose‐derived stem cells is underway to determine how stem cells respond in vivo.
Basal prostaglandin levels are required for PYK2 expression and Ang II‐dependent MAPK phosphorylation in intestinal epithelial cells
Authors: Slice Lee Warren , Wu Steven S. , Pham Hung , Vincenti Romina , Rozengurt Enrique 
Published: June 2021

ObjectiveAng II rapidly induces PYK2 phosphorylation on Tyr402 along with increased PG production in epithelial cells suggesting possible feedback regulation of Ang II signaling by PGs. We investigated the role of PGs in PYK2 signaling in cells over‐expressing 15‐hydroxyprostaglandin dehydrogenase (PGDH), an enzyme that inactivates PGs.MethodsIntestinal epithelial cells (IEC‐18) were transduced using lentivirus to express green fluorescent protein (18.GFP) or PGDH (18.PGDH).ResultsAng II induced PYK2 Tyr402 phosphorylation in IEC‐18 and 18.GFP cells. Both cell lines produced low basal levels of PGs that were increased by stimulation with Ang II or EGF. These agonists induced ERK phophorylation, which was blocked by AG1478. PG levels were undetectable in 18.PGDH cells and did not increase with stimulation. PYK2 expression was absent in 18.PGDH cells. Ang II did not induce ERK phosphorylation. Conversely, EGF induced ERK phosphorylation. Ang II‐dependent ERK phosphorylation was rescued by expression of wt PYK2 but not by an inactive PYK2 mutant. Reduction of PYK2 expression by siRNA in IEC‐18 cells correlated with a decrease in Ang II‐dependent ERK phosphorylation.ConclusionsBasal PG levels are required to maintain PYK2 expression in IEC‐18 cells. In turn, PYK2 plays a critical role in mediating ERK signaling by Ang II. Supported by RO1 DK061485
A role for Drak2 in the germinal center reaction and the antibody response
Authors: Al‐Qahtani Ahmed , Xu Jack , Zan Hong , Walsh Craig , Casali Paolo 
Published: June 2021

DAP‐related apoptotic kinase‐2 (Drak2), a DAP family member, is highly expressed in B and T lymphocytes in the human and the mouse. To determine whether Drak2 plays a role in B cell activation and differentiation, we analyzed germinal center (GC) development in drak2−/− mice immunized with the T‐dependent conjugated hapten NP‐CGG. In drak2−/− mice, spleen GCs were normal in size and morphology, but their number was reduced by three to five‐fold as compared to wild type littermates. This was not due to a defect in B cell proliferation, as BrdU uptake in vivo and CFSE staining in vitro of B cells was comparable in Drak2‐deficient and wild type B cells. Nevertheless, the proportion of apoptotic GC B and T cells in drak2−/− mice was significantly higher than that in wild type littermates as shown by7‐AAD and TUNEL staining experiments. As a result, the generation of high affinity IgG antibodies was impaired in drak2−/− mice. Enforced expression of bcl‐xl in T cells of these mice increased the number of the GCs and rescued the high affinity IgG response to NP‐CGG. This was consistent with the findings that the somatic hypermutation and class switch DNA recombination machineries were inherently normal in drak2−/− mice. Thus, our findings suggest a novel role of Drak2 in regulating the GC reaction and the response to TD antigens.This work is supported by NIH grants AI 45011, AI 60573 and AR 40908.
The roles of recombination signal sequence efficiency and location within the TCR β locus on the relative frequencies with which V β gene segments participate in V(D)J recombination
Authors: Cowell Lindsay Grey , Devlin Blythe , Hsieh Chia‐San , Harley Susan , Li Jie , Louise markert Mary 
Published: June 2021

The different T cell receptor (TCR) β variable (Vβ) gene segments do not appear in the naïve TCR repertoire with equal frequencies. To identify the relative roles of recombination signal (RS) sequence efficiency and location within the TCRβ locus in determining the bias in Vβ gene segment utilization, we are studying TCR diversification after thymus transplantation in athymic infants with complete DiGeorge anomaly. Thymus transplantation reconstitutes T cells, and the course of T cell development allows study of TCR diversification. We sequenced mRNA from peripheral blood T cells sampled from two patients at multiple times after thymus transplantation. For each of six Vβ gene segments, we estimated the diversity of rearrangements from the number of unique rearrangements utilizing that gene segment and the number of identical sequences for each unique rearrangement. The RS recombination efficiency was predicted using the RS Information Content (RIC) score computed using a statistical model of mouse RS. We find that Vβ gene segment diversity varies significantly in the early repertoire indicating differences in the relative frequencies of recombination. Neither RS efficiency nor distance from the D‐J cluster solely determine the observed differences, rather the two factors appear to interact, jointly influencing recombination frequencies.This work is supported by an NIH grant to MLM and a BWF award to LGC.
Regulation of CD4 T Cell Differentiation by CD44
Authors: Guan Hongbing , Nagarkatti Prakash , Nagarkatti Mitzi 
Published: June 2021

CD4 T cells can polarize to Th1, Th2 and newly emerged Th17 lineage. The involvement of cytokines and signaling pathways that trigger such polarization are largely known. However, cells and molecules regulating the differentiation are not identified, especially in consideration of primary versus secondary immune response. In the current study, we found that CD44 plays an important role in CD4 T cell differentiation. By comparing immune responses to SRBC and OVA in CD44‐deficient and CD44‐sufficient mice, we observed that CD44 deficiency triggers a decreased Th1 immunity and an increased Th2 response. The decreased Th1 response correlated with a decrease in many of the components including macrophage migration, delayed‐type hypersensitivity, IgG2a production, and SRBC‐induced hemagglutination. However, there was an increase in IgG1 production. CD44‐deficient mice also had a down‐regulated expression of T‐bet and Th1‐cytokines but an enhanced expression of GATA3 and Th2‐cytokines. The skewed immunity occurred in either primary or secondary immune response. The decreased serum IL‐17 production, splenic Th17 population and dendritic cell functions in CD44‐deficient mice may contribute towards a shift from Th1 to Th2 cell polarization.(This work was supported in part by NIH grants: AI053703, ES09098, AI058300, DA016545, HL058641 and P01AT003961).
Aging down‐regulates the transcription factor E2A, activation‐induced cytidine deaminase and Ig class switch in human B cells
Authors: Blomberg Bonnie B , Frasca Daniela , Landin Ana Marie , Riley Richard L 
Published: June 2021

The capacity to class switch the Ig heavy chain is critical to the effectiveness of humoral immune responses in mice and humans. We have previously shown in mice that the E2A‐encoded transcription factor E47 is down‐regulated in old splenic B cells. This leads to a reduction in the activation‐induced cytidine deaminase (AID), which is known to induce class switch recombination (CSR) and Ig somatic hypermutation (SHM). We have extended our study here to investigate whether aging also affects antibody production, E47 and AID expression in B cells isolated from the peripheral blood (PB) of human subjects (18–86 years). Our results obtained with activated CD19+ B cells show that the expression of E47, AID and Igγ1 circle transcripts progressively decrease with age. We also show an age‐related decline in the percentage and numbers of switch memory B cells, no change in the percentage but a decline in the numbers of IgM memory B cells and an increase in the percentage but not in the numbers of naive B cells, consistent with our data on the decrease seen in CSR in vitro. In addition, we suggest that the subsets of B cells able to class switch in culture are the naïve and the IgM memory populatio, depending on the stimulus. Our results give possible molecular mechanisms for an intrinsic decrease in B cell function and the humoral immune response in aging.This work is supported by NIH AG‐17618, AG‐23717 (BBB) and AG025256 and AI064591 (RLR)