bluuebunny/crossref_metadata_2025_split huggingface dataset:
Minimum Inhibitory Concentration Assays for Multidrug Resistant Gram‐Negative Bacterial Pathogens
Authors: Edgar Jennifer M. , Zhao Hang , Brakke Sabrina A. , Wise John G. 
Published: April 2020

Antibiotic resistance by bacterial pathogens is a persistent problem in medicine. One method of resistance is through RND efflux transporters, which can move antibiotics out of the cells and the periplasm, thus preventing cell death. Many of these transporters can move several very different antibiotics out of the cells, thus conferring multidrug resistance to the pathogens. This project focuses on one such RND transporter found in Neisseria gonorrhoeae known as mtrCDE. Our goal is to identify potential inhibitors of mtrCDE by observing their effects on the minimum inhibitory concentrations (MICs) of antibiotics. Ultimately, we aim to develop inhibitors of mtrCDE with the goal of restoring antibiotic sensitivity to antibiotic‐resistant N. gonorrhoeae. Potential inhibitors have been identified through computational means. In the system described here, the genes for mtrCDE have been transformed into an E. coli strain that has had the homologous E. coli RND transporter deleted for facilitating testing. We have attempted to optimize MIC assays to determine the minimum concentration of antibiotic required to inhibit the growth of cells expressing the mtrCDE genes. To date, the largest effects in these assays have been observed with the detergent Triton X‐100. In addition, the plasmid encoding mtrCDE included a gene conferring chloramphenicol resistance for selection. The media for initial growth of cells contained chloramphenicol to maintain this selection. Initial studies showed that inclusion of chloramphenicol with other antibiotics overwhelms even resistant bacteria. The effects of inclusion of dimethyl sulfoxide (DMSO), a commonly used carrier vehicle for experimental compounds, was tested in the assays since our compound libraries use this solvent. Experiments suggested that inclusion of low concentrations of DMSO does not affect the MIC values observed, but that the cells do reflect a dose response to varying concentrations of DMSO that needs to be carefully controlled. Continuing optimization of these assays with various antibiotics is being performed to determine MIC values, compare them with reported MIC values, and identify antibiotics that are effluxed by mtrCDE that have no published MIC values for N. gonorrhoeae or E. coli. We report here these and other results of our MIC assay optimization for multidrug resistant, gram‐negative bacterial pathogens.Support or Funding InformationDepartment of Biological Sciences, the Center for Drug Discovery, Design and Delivery (CD4), the Center for Scientific Computation, Engaged Learning, and the Hamilton Scholars Program, Southern Methodist University, Dallas, TX
From Cells‐to‐Organism: Impact of Dyslipidemia on Inwardly Rectifying K+ Channels and Cerebral Vascular Function
Authors: Kowalewska Paulina M. , Sancho Maria , Fabris Sergio , Huff Murray W. , Gros Robert , Welsh Donald G. 
Published: April 2020

Recent studies have noted that dyslipidemia can diminish dilatory function of resistance arteries by altering the activity of ion channels that set membrane potential. Focusing on the cerebral circulation, this study determined whether inwardly rectifying K+ (KIR) channels are targeted early in dyslipidemia and if alterations impact blood flow control. Experiments began at the cellular level (patch‐clamp electrophysiology) and then were extended to isolated arteries (pressure myography) and whole animals (arterial spin‐labelling magnetic resonance imaging). Initial lipid analysis confirmed the dyslipidemic state of LDLR−/− (normal chow) and C57BL/6 mice fed a high‐cholesterol high‐fat (HFHC) diet for 8 weeks; note aortic plaque formation was absent in these animal models. Patch‐clamp electrophysiology revealed a marked reduction in endothelial but not smooth muscle KIR activity in both dyslipidemic models. Flow activation of KIR was also reduced in endothelial cells from LDLR−/− and HFHC mice. However, endothelial KIR activity was recovered in dyslipidemic mice by depleting the plasma membrane of cholesterol. Consistent with these cellular changes, we observed diminished shear‐induced vasodilation in cerebral arteries isolated from dyslipidemic animals. To our surprise, these cellular/tissue level changes didn’t alter cerebral blood flow at baseline or in response to a blood pressure challenge (phenylephrine injection through a peritoneal catheter, 0.816 mg/kg). The maintenance of blood flow control was observed across a full range of structures including the cortex, cerebral nuclei, hippocampus, thalamus, hypothalamus and midbrain. In closing, our findings highlight that while KIR channel function is targeted early on in dyslipidemia, compensatory mechanisms can maintain brain blood flow to preserve neurological function.Support or Funding InformationCanadian Institutes of Health Research
Prevention of T Cell Activation in Response to Placental Ischemia Improves Hypertension and Natural Killer Cell Number During Pregnancy
Authors: Campbell Nathan Edward , Deer Evangeline , Amaral Lorena , Reeve Krisin , Fitzgerald Sarah , Herrock Owen , Franks Michael , Usry Nathan , Ibrahim Tarek , Lamarca Babbette 
Published: April 2020

Preeclampsia (PE), new onset hypertension during pregnancy, is the leading cause of death and morbidity world‐wide for the mother and fetus during pregnancy. The Reduced Uterine Perfusion Pressure Rat Model of Preeclampsia (RUPP) exhibits many characteristics of PE including hypertension, suppressed regulatory T cells (TRegS) associated with increased CD4+ T cells and B cells secreting agonistic autoantibodies to the AngII receptor (AT1‐AA). We have previously shown that blockade of T‐helper cells improves blood pressure and lowers AT1‐AA secretion. A potential mechanism for the decreased blood pressure is decreased cytolytic natural killer (cNK) cells. Abatacept is a fusion molecule designed to inhibit T cell co‐stimulation in response to antigens and is used to treat autoimmune diseases. We hypothesize that treatment with Abatacept will prevent the activation of T‐helper cells and therefore lower AT1‐AA as a mechanism to lower the activity of NK cells in response to placental ischemia in RUPP rats. Abatacept was given on day 13 via the jugular vein. On day 19, blood and tissues were collected, blood pressure (MAP), pup weight and NK cells were measured by flow cytometry in the blood and placenta. A one‐way ANOVA was used for statistical analysis. On GD19, MAP significantly increased in RUPP 119±2 mmHg (n=7, p<0.05) compared to NP controls 101±2 mmHg (n=7) and was normalized with abatacept (100±2.02 mmHg (n=10, p<0.05). Compared to the NP controls (2.216±0.054, n=7), pup weight significantly decreased in RUPP (1.919±0.113, n=7, p<0.05) and was 1.934± 0.050, with Abatacept (n=10, p<0.05). Circulating and placental total NK cells were 45±9, 59±11 % gate in NP rats (n=7, n=5), 59±4, 72±13 % gate in RUPP rats (n=7, n=4), which significantly decreased to 32±7, 25±9 % gate with Abatacept (n=10, p<0.05; n=10, p<0.05). Our findings indicate that prevention of T cell activation lowers total NK cell number and blood pressure in response to placental ischemia of pregnancy.Support or Funding Information2R01HD067541P20GM121334 T32HL105324
Stress Preconditioning Effects on Heart Rate and Blood Pressure under Circumstances of Gastric and Small Intestine Injury Induced by Indomethacin in Conscious Rats
Authors: Filaretova Ludmila , Yarushkina Natalia 
Published: April 2020

Nonsteroidal anti‐inflammatory drugs (NSAIDs) are commonly used medications. However NSAIDs exert side effects not only in the stomach and the small intestine but also in cardiovascular system. A disorder of the circadian heart rate (HR) under circumstances of indomethacin (IM)‐induced gastric and small intestinal injury is potentially lethal factor and our previous experimental findings confirmed this fact. Preconditioning is one of perspective approaches to protect the heart and other organs against adverse influences. We demonstrated previously that glucocorticoids released during mild stress contribute to protection of the gastric mucosa against severe stress through maintaining various links of the general body homeostasis, including blood pressure (BP). Here we studied the effects of stress preconditioning on HR and BP under circumstances of gastric and small intestine injury induced by IM in conscious rats. Preliminary fasting (24 h) rats were subjected IM (35 mg/kg, sc) administration with preconditioning stress (cold‐restraint, 10 °C, 30 min and keeping at room temperature 1 h before IM administration) or without it. HR and BP were measured by non‐invasive tail cuff method before IM injection and 4, 24 and 48 h after IM administration in stressed and non‐stressed animals. The gastric and the small intestinal mucosa were examined for injury 4 h (formation of the gastric erosions) and 24 and 48 h (formation of the small intestinal injury) after IM administration. Plasma corticosterone levels were also measured. IM administration induced formation of gastric erosions (4 h after its injection) and their healing for 48 h was followed by a development of the small intestinal injury. Formation of gastric erosions caused an elevation of corticosterone levels 4 h after IM; their following healing resulted in a decrease of IM‐induced corticosterone levels 24 and 48 h after IM injection till baseline level. IM‐induced gastrointestinal injury was accompanied by a gradual decrease of systolic BP and increase of the HR for 48 h after IM. Preconditioning stress reduced IM‐induced gastric erosions as well as small intestinal injury 4 and 24 h after its injection, respectively, and recovered HR and systolic BP 48 h after IM. Thus, the data suggest that preconditioning stress may reduce the vulnerability of the gastric and the small intestinal mucosa to ulcerogenic action of IM and stabilizes the hemodynamic parameters.Support or Funding InformationThe study was supported by grant of Russian Science Foundation (RSF) N 19‐15‐00430.
Polyethylene‐glycol chitosan hydrogel accelerates traumatic wound healing in diabetic mice
Authors: García Angel Eduardo Bárcenas , Merino Miriam Veronica Flores , Tolosa Ibeth Mayerly Gaitan , Muñoz Daniela Rodríguez , López Miguel Angel Camacho , Pantoja Rigoberto Oros 
Published: April 2020

Wounds are considered a public health problem worldwide; it represents a significant economic impact on health systems. Diabetic lesions, microvascular dysfunction, trauma and burns, are some factors related to poor repair. Nowadays in regenerative medicine, biocompatible biomaterials (e.g., hydrogels) have proven been effective in regenerative processes. Therefore, preformed synthetic matrices could be a therapeutic alternative to accelerate wound repair.Objectiveto evaluate the Polyethylene‐glycol chitosan hydrogel (hg‐PEGDA‐Q) effect on traumatic wounds. Two CD1 mice (10 weeks, n = 5) were used: healthy control (CT) and with alloxan‐induced Diabetes Mellitus (DM) (200 mg / kg). Under anaesthesia, two traumatic dorsal wounds separated by 1 cm (diameter (⌀) 5 mm, area 19.63mm2) were caused to each mouse: a) without treatment (WT) (proximal wound) and b) with hydrogel PEGDA‐Q (⌀ 5 mm, thickness 2 mm, distal wound). The macro and microscopic evolution were evaluated on 12 postoperative day. For analyse the macroscopic images were rescaled through a vernier and ImageJ software (1: 1 mm scale). hg‐PEGDA‐Q matrix was synthesized by sequential method and photopolymerization.Resultsin CT group, hg‐PEGDA‐Q decreased the diameter and area with respect to untreated wound (hg‐PEGDA‐Q vs. WT) (⌀ 2.71 ± 0.64 mm vs. 3.71 ± 0.27 mm; area 5.79 ± 1.67 mm2 vs. 9.23 ± 1.97 mm2). In DM group, the same behaviour was observed with hydrogel (DM hg‐PEGDA vs. DM‐WT) (⌀ 3.04 ± 0.64 mm vs. 3.90 ± 0.29mm; area 6.29 ± 2.35 mm2 vs. 12.01 ± 3.66 mm2). Regarding initial diameter (5 mm, day 0), in control group, wound retraction (WR) was (hg‐PEGDA‐Q 45% vs. WT 25%), while in diabetic group WR was (hg‐PEGDA‐Q 39% vs. WT 21%). Comparing the initial area (19.63 mm2 at day 0), in control group the WR was (hg‐PEGDA‐Q 70% vs. WT 52%), while in DM group the WR was (hg‐PEGDA‐Q 67 % vs. WT 38%). Histomorphological analysis: hg‐PEGDA‐Q generated complete reepithelialization and dermo‐epidermal changes suggesting an advanced wound healing process compared to control group without treatment. DM group treated with hg‐PEGDA‐Q changes were similar, however consolidation was lower. In contrast DM WT group, reepithelialization and wound consolidation were deficient. Results indicate PEGDA‐Q hydrogel scaffolding network could be a therapeutic alternative to accelerate healing processes in normal and diabetic conditions
Anatomical Basis of Epileptogenesis in a Mouse Model of Traumatic Brain Injury
Authors: Golub Victoria , Reddy Samba 
Published: April 2020

Post‐traumatic epilepsy (PTE) is characterized by progressive spontaneous recurrent seizures (SRS) following traumatic brain injury (TBI). PTE is poorly controlled by current medications and the molecular pathophysiology of PTE is unclear. A critical step for preventing PTE is to determine a key pathway that drives disease progression during the “latent period” after TBI, termed epileptogenesis. The potential mechanisms of underlying post‐traumatic epileptogenesis include neuroinflammation, degeneration of neuronal cells, and alterations in the hippocampal neurogenesis and mossy fiber sprouting. In this study, we sought to demonstrate a causal anatomical relationship between neuroinflammation and/or neurodegeneration and the onset of PTE in mice. TBI was induced in mice by a controlled‐cortical impact paradigm and were then monitored by video‐EEG recording for 120 days with a deep electrode placed within the contralateral hippocampus. At days 1, 3, 7, 30, 60, 120 post‐TBI, brains were fixed for immunohistochemistry and analyzed for principal neurons (NeuN+), interneurons (PV+), astrogliosis (GFAP+), microgliosis (IBA1+), and neurogenesis (DCX). Alterations in hippocampal and hemispheric architecture were visualized with quantitative analysis. Pronounced atrophy was evident within the ipsilateral hemisphere in the form of large lesions which extended from the cortex to the hippocampus by 120 days. In the contralateral hippocampus, inflammatory markers of microgliosis and astrogliosis reached peak levels within the first week before steadily declining throughout the 120‐day observation period. In contrast, neurodegeneration of NeuN+ cells and PV+ interneurons was not evident at these early stages, but cell loss became unmistakable starting 30 days post‐TBI. By this point, nearly 30% of PV+ interneurons were lost, with the dentate gyrus serving as the greatest region of cell loss (~40% loss). These studies were repeated using a moderate 1mm injury to emphasize the relationship between injury severity and neurodegeneration. Our findings are reminiscent of preferential loss of inhibitory interneurons in epilepsy patients and suggest that early neuroinflammation may catapult neurodegeneration within the damaged areas, which appears to be a critical mechanism for the onset of epileptogenesis. Specifically, progressive loss of PV+ GABAergic interneurons within the dentate gyrus correlates with progression of SRS from 30 to 60 days, coinciding with the onset of SRS at 39 days post‐TBI.Support or Funding Information**Funded by DOD Award #W81XWH‐16‐1‐0660**
Sensitization of group lV skeletal muscle afferents in type 1 diabetic rats
Authors: Ishizawa Rie , Kim Han Kyul , Hotta Norio , Iwamoto Gary A. , Vongpatanasin Wanpen , Mitchell Jere H. , Smith Scott A. , Mizuno Masaki 
Published: April 2020

The blood pressure (BP) response to exercise is abnormally exaggerated in type 1 diabetes mellitus (T1DM). However, the mechanisms underlying the potentiated BP response remain largely unclear. Sensory information from working muscle, generated by activation of mechanically and metabolically sensitive muscle afferents, is known to contribute importantly to this exercise‐induced exaggeration in BP. Moreover, receptors for advanced glycation end products (RAGE) and protein kinase C (PKC) interact to modulate neuronal function, including muscle afferents. It is possible that the interactive relationship between RAGE and PKC is altered in T1DM. Therefore, it was hypothesized that the potentiated exercise‐induced BP response in T1DM is mediated by sensitization of skeletal muscle afferent fibers via an overactive RAGE/PKC signaling pathway.PURPOSETo investigate 1) action potential responses to mechanical and chemical stimulation in muscle afferents of healthy and T1DM rats in vitro, 2) the impact of T1DM on plasma levels of high‐mobility group box‐protein 1 (HMGB‐1), a RAGE ligand, and 3) the impact of T1DM on PKC activation in dorsal root ganglion (DRG) subserving skeletal muscle afferent neurons.METHODST1DM was induced in Sprague‐Dawley rats by intraperitoneally injecting a single dose of 50 mg/kg streptozotocin. In healthy control animals, only saline was injected. At 1–3 weeks after the injection, the function of mechanically (application of a 0–196 mN ramped stimulus) or chemically (administration of 1 μM capsaicin) activated group IV fibers were assessed by obtaining single‐fiber recordings using the extensor digitorum longus muscle‐nerve preparation. Plasma HMGB1 was determined using ELISA. Phosphorylated PKC protein levels were quantified in DRG (L3‐L5) by western blotting.RESULTST1DM rats exhibited hyperglycemia after overnight fasting (P<0.05). Plasma insulin in T1DM tended to be lower as compared to control animals (P=0.09). Spontaneous activity in group IV fibers was significantly larger in diabetic rats than in control animals (P<0.05). Compared to control, response magnitudes to mechanical stimulation (P<0.01) and capsaicin exposure (P=0.01) in group IV afferents were significantly greater in T1DM. Plasma HMGB1 levels were significantly higher in T1DM as compared with control (P<0.01). T1DM showed markedly increased phosphorylated PKC levels in DRGs compared with control (P<0.05).CONCLUSIONSIn T1DM, the sensitivity of group IV skeletal muscle afferent fibers to mechanical and chemical stimuli is abnormally increased. The data likewise suggest this enhanced afferent sensitivity may be due to augmented activation of the RAGE/PKC pathway. Importantly, these changes likely contribute significantly to the exaggerated pressor response to exercise characteristic of T1DM.Support or Funding InformationSupported by Lawson & Rogers Lacy Research Fund and SHP Interdisciplinary Research Grant Program.
Creatine Supplementation Exhibits Sex Differences in White Adipose Tissue and Increases Mitochondrial Markers in Female Rats
Authors: Ryan Chantal Rose , Dunham Tyler , Murphy Jensen , Roy Brian D. , MacPherson Rebecca E.K. 
Published: April 2020

Activation of white adipose tissue (WAT) thermogenesis, known as WAT browning, has emerged as an attractive approach to treat obesity and obesity‐related diseases. Traditionally BAT or browning WAT has been defined by the expression of uncoupling protein 1 (UCP1), a mitochondrial protein that uncouples respiration from ATP production. However, recent work has highlighted creatine metabolism or futile cycling as a potential thermogenic pathway. Creatine‐driven futile cycling is a catabolic process which results in ATP oxidation by mitochondrial creatine kinase, resulting in the phosphorylation of creatine and increases in ADP concentrations that drive thermogenic respiration. The purpose of the present study was two‐fold: 1) to determine the effects of creatine supplementation on markers of WAT browning, and 2) to determine if creatine supplementation exhibits sex differences. Thirty‐two Sprague‐Dawley rats (16 male, 16 female) were randomly assigned to one of four experimental groups: control, 2.5g/L, 5g/L and 10g/L of creatine monohydrate (CM) and 1% sucrose via drinking water. Rats had ad libitum access to their drinking water and a standard chow diet (AIN‐93G) throughout the study. Following the 8‐week intervention, brown interscapular adipose (BAT) and white subcutaneous inguinal (iWAT) fat depots were collected. Western blotting analysis demonstrated no significant changes in BAT samples for both males and females. Males had lower cytochrome C than females with 10g/L of creatine monohydrate (p<0.05). In iWAT, mitochondrial markers (COXIV, PDH, citrate synthase, and cytochrome C) and GAMT exhibit no changes in males, however, a decrease in UCP‐1 at 5g/L compared to control was observed (p<0.05). Females exhibit a lower control PDH content than males (p<0.01) in iWAT, accompanied by an increase in PDH levels at all doses of CM compared to control (p<0.05). Furthermore, in females COXIV and cytochrome C presented significant increases with 5g/L and 10g/L, respectively (p<0.05). Both males and females did not present with body weight differences despite dose differences. This study presents novel work demonstrating that female WAT exhibits less mitochondrial markers than males under control conditions, however it demonstrates the potential for CM supplementation to increase female adipose thermogenicity to a similar level observed in males.Support or Funding InformationSupported by NSERC, Canada