Recent Research Articles from UNTHSC

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Updated: 2 hours 35 min ago

Neuritin 1 promotes retinal ganglion cell survival and axonal regeneration following optic nerve crush.

2 hours 35 min ago

Neuritin 1 promotes retinal ganglion cell survival and axonal regeneration following optic nerve crush.

Cell Death Dis. 2015;6:e1661

Authors: Sharma TP, Liu Y, Wordinger RJ, Pang IH, Clark AF

Abstract
Neuritin 1 (Nrn1) is an extracellular glycophosphatidylinositol-linked protein that stimulates axonal plasticity, dendritic arborization and synapse maturation in the central nervous system (CNS). The purpose of this study was to evaluate the neuroprotective and axogenic properties of Nrn1 on axotomized retinal ganglion cells (RGCs) in vitro and on the in vivo optic nerve crush (ONC) mouse model. Axotomized cultured RGCs treated with recombinant hNRN1 significantly increased survival of RGCs by 21% (n=6-7, P<0.01) and neurite outgrowth in RGCs by 141% compared to controls (n=15, P<0.05). RGC transduction with AAV2-CAG-hNRN1 prior to ONC promoted RGC survival (450%, n=3-7, P<0.05) and significantly preserved RGC function by 70% until 28 days post crush (dpc) (n=6, P<0.05) compared with the control AAV2-CAG-green fluorescent protein transduction group. Significantly elevated levels of RGC marker, RNA binding protein with multiple splicing (Rbpms; 73%, n=5-8, P<0.001) and growth cone marker, growth-associated protein 43 (Gap43; 36%, n=3, P<0.01) were observed 28 dpc in the retinas of the treatment group compared with the control group. Significant increase in Gap43 (100%, n=5-6, P<0.05) expression was observed within the optic nerves of the AAV2-hNRN1 group compared to controls. In conclusion, Nrn1 exhibited neuroprotective, regenerative effects and preserved RGC function on axotomized RGCs in vitro and after axonal injury in vivo. Nrn1 is a potential therapeutic target for CNS neurodegenerative diseases.

PMID: 25719245 [PubMed - as supplied by publisher]

In vitro protection by pyruvate against cadmium-induced cytotoxicity in hippocampal HT-22 cells.

2 hours 35 min ago
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In vitro protection by pyruvate against cadmium-induced cytotoxicity in hippocampal HT-22 cells.

J Appl Toxicol. 2014 Aug;34(8):903-13

Authors: Poteet E, Winters A, Xie L, Ryou MG, Liu R, Yang SH

Abstract
Cadmium is a toxic metal with no biological function in higher-order mammals. Humans are exposed to cadmium environmental contamination and the mechanism underlying the cadmium's cytotoxicity is unclear. To better understand this mechanism, we employed murine hippocampal HT-22 cells to test the in vitro effects of cadmium toxicity. Our study indicated that cadmium inhibits both mitochondria oxidative phosphorylation and glycolysis. In turn, this causes depolarization of mitochondrial membrane potential, increase of superoxide production and decrease of ATP generation. Furthermore, we demonstrated that the detrimental action of cadmium in bioenergetics could be mitigated by pyruvate, an intermediate metabolic product. Pyruvate decreased superoxide production, maintained mitochondrial membrane potential, restored glycolysis, mitigated the decrease in cellular ATP and attenuated cadmium cytotoxicity. Our study provides the first evidence that pyruvate might offer promising therapy for cadmium poisoning.

PMID: 24037965 [PubMed - indexed for MEDLINE]

An Attachment-Based Description of the Medial Collateral and Spring Ligament Complexes.

18 hours 36 min ago

An Attachment-Based Description of the Medial Collateral and Spring Ligament Complexes.

Foot Ankle Int. 2015 Feb 23;

Authors: Cromeens BP, Kirchhoff CA, Patterson RM, Motley T, Stewart D, Fisher C, Reeves RE

Abstract
BACKGROUND: Anatomy of the medial collateral and spring ligament complexes has been the cause of confusion. The anatomic description is highly dependent on the source studied and little agreement exists between texts. In addition, inconsistent nomenclature has been used to describe the components. This study attempted to clarify confusion through the creation of a 3D ligament map using attachment-based dissection.
METHODS: Nine fresh foot and ankle specimens were observed. The medial collateral ligament and spring ligament complexes were dissected using their attachment sites as a guide to define individual components. Each component's perimeter and thickness was measured and each bony attachment was mapped using a microscribe 3D digitizer.
RESULTS: Five components were identified contributing to the ligament complexes of interest: the tibiocalcaneonavicular, superficial posterior tibiotalar, deep posterior tibiotalar, deep anterior tibiotalar, and inferoplantar longitudinal ligaments. The largest component by total attachment area was the tibiocalcaneonavicular ligament followed by the deep posterior tibiotalar ligament. The largest ligament surface area of attachment to the tibia and talus was the deep posterior tibiotalar ligament. The largest attachment to the navicular and calcaneus was the tibiocalcaneonavicular ligament, which appeared to function in holding these bones in proximity while supporting the head of the talus.
CONCLUSION: By defining complex components by their attachment sites, a novel, more functional and reproducible description of the medial collateral and spring ligament complexes was created.
CLINICAL RELEVANCE: The linear measurements and 3D maps may prove useful when attempting more anatomically accurate reconstructions.

PMID: 25712121 [PubMed - as supplied by publisher]

Stress Induces p38 MAPK-Mediated Phosphorylation and Inhibition of Drosha-Dependent Cell Survival.

Thu, 02/26/2015 - 3:29am

Stress Induces p38 MAPK-Mediated Phosphorylation and Inhibition of Drosha-Dependent Cell Survival.

Mol Cell. 2015 Feb 19;57(4):721-34

Authors: Yang Q, Li W, She H, Dou J, Duong DM, Du Y, Yang SH, Seyfried NT, Fu H, Gao G, Mao Z

Abstract
MicroRNAs (miRNAs) regulate the translational potential of their mRNA targets and control many cellular processes. The key step in canonical miRNA biogenesis is the cleavage of the primary transcripts by the nuclear RNase III enzyme Drosha. Emerging evidence suggests that the miRNA biogenic cascade is tightly controlled. However, little is known whether Drosha is regulated. Here, we show that Drosha is targeted by stress. Under stress, p38 MAPK directly phosphorylates Drosha at its N terminus. This reduces its interaction with DiGeorge syndrome critical region gene 8 and promotes its nuclear export and degradation by calpain. This regulatory mechanism mediates stress-induced inhibition of Drosha function. Reduction of Drosha sensitizes cells to stress and increases death. In contrast, increase in Drosha attenuates stress-induced death. These findings reveal a critical regulatory mechanism by which stress engages p38 MAPK pathway to destabilize Drosha and inhibit Drosha-mediated cellular survival.

PMID: 25699712 [PubMed - in process]

NKp44 and Natural Cytotoxicity Receptors as Damage-Associated Molecular Pattern Recognition Receptors.

Thu, 02/26/2015 - 3:29am

NKp44 and Natural Cytotoxicity Receptors as Damage-Associated Molecular Pattern Recognition Receptors.

Front Immunol. 2015;6:31

Authors: Horton NC, Mathew PA

Abstract
Natural killer (NK) cells are a key constituent of the innate immune system, protecting against bacteria, virally infected cells, and cancer. Recognition and protective function against such cells are dictated by activating and inhibitory receptors on the surface of the NK cell, which bind to specific ligands on the surface of target cells. Among the activating receptors is a small class of specialized receptors termed the natural cytotoxicity receptors (NCRs) comprised of NKp30, NKp46, and NKp44. The NCRs are key receptors in the recognition and termination of virally infected and tumor cells. Since their discovery over 10 years ago, ligands corresponding to the NCRs have largely remained elusive. Recent identification of the cellular ligands for NKp44 and NKp30 as exosomal proliferating cell nuclear antigen (PCNA) and HLA-B-associated transcript 3 (BAT3), respectively, implicate that NCRs may function as receptors for damage-associated molecular pattern (DAMP) molecules. In this review, we focus on NKp44, which surprisingly recognizes two distinct ligands resulting in either activation or inhibition of NK cell effector responses in response to tumor cells. The inhibitory function of NKp44 requires further study as it may play a pivotal role in placentation in addition to being exploited by tumors as a mechanism to escape NK cell killing. Finally, we suggest that the NCRs are a class of pattern recognition receptors, which recognize signals of genomic instability and cellular stress via interaction with the c-terminus of DAMP molecules localized to the surface of target cells by various co-ligands.

PMID: 25699048 [PubMed]

Pharmacological modulation of abnormal involuntary DOI-induced head twitch response movements in male DBA/2J mice: II. Effects of D3 dopamine receptor selective compounds.

Thu, 02/26/2015 - 3:29am

Pharmacological modulation of abnormal involuntary DOI-induced head twitch response movements in male DBA/2J mice: II. Effects of D3 dopamine receptor selective compounds.

Neuropharmacology. 2015 Feb 17;

Authors: Rangel-Barajas C, Malik M, Mach RH, Luedtke RR

Abstract
We recently reported on the characterization of the hallucinogen 2,5-dimethoxy-4-methylamphetamine's (DOI) ability to elicit a head twitch response (HTR) in DBA/2J mice and the ability of D2 vs. D3 dopamine receptor selective compounds to modulate that response. For these studies, the ability of D3 vs. D2 dopamine receptor selective compounds to attenuate the DOI-dependent HTR was examined. WC 10, a D3 dopamine receptor weak partial agonist with 40-fold binding selectivity for D3 vs. D2 dopamine receptors, produced a dose-dependent decrease in the DOI-induced HTR (IC50 = 3.7 mg/kg). WC 44, a D3 receptor selective full agonist, also inhibited the DOI-induced HTR (IC50 = 5.1 mg/kg). The effect of two D3 receptor selective partial agonists, LAX-4-136 and WW-III-55, were also evaluated. These analogs exhibit 150-fold and 800-fold D3 vs. D2 binding selectivity, respectively. Both compounds inhibited the HTR with similar potency but with different maximum efficacies. At 10 mg/kg WW-III-55 inhibited the HTR by 95%, while LAX-4-136 administration resulted in a 50% reduction. In addition, DOI (5 mg/kg) was administered at various times after LAX-4-136 or WW-III-55 administration to compare the duration of action. The homopiperazine analog LAX-4-136 exhibited greater stability. An assessment of our test compounds on motor performance and coordination was performed using a rotarod test. None of the D3 dopamine receptor selective compounds significantly altered latency to fall, suggesting that these compounds a) did not attenuate the DOI-dependent HTR due to sedative or adverse motor effects and b) may have antipsychotic/antihallucinogenic activity.

PMID: 25698528 [PubMed - as supplied by publisher]

Pathogenesis of chronic hyperglycemia: from reductive stress to oxidative stress.

Thu, 02/26/2015 - 3:29am
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Pathogenesis of chronic hyperglycemia: from reductive stress to oxidative stress.

J Diabetes Res. 2014;2014:137919

Authors: Yan LJ

Abstract
Chronic overnutrition creates chronic hyperglycemia that can gradually induce insulin resistance and insulin secretion impairment. These disorders, if not intervened, will eventually be followed by appearance of frank diabetes. The mechanisms of this chronic pathogenic process are complex but have been suggested to involve production of reactive oxygen species (ROS) and oxidative stress. In this review, I highlight evidence that reductive stress imposed by overflux of NADH through the mitochondrial electron transport chain is the source of oxidative stress, which is based on establishments that more NADH recycling by mitochondrial complex I leads to more electron leakage and thus more ROS production. The elevated levels of both NADH and ROS can inhibit and inactivate glyceraldehyde 3-phosphate dehydrogenase (GAPDH), respectively, resulting in blockage of the glycolytic pathway and accumulation of glycerol 3-phospate and its prior metabolites along the pathway. This accumulation then initiates all those alternative glucose metabolic pathways such as the polyol pathway and the advanced glycation pathways that otherwise are minor and insignificant under euglycemic conditions. Importantly, all these alternative pathways lead to ROS production, thus aggravating cellular oxidative stress. Therefore, reductive stress followed by oxidative stress comprises a major mechanism of hyperglycemia-induced metabolic syndrome.

PMID: 25019091 [PubMed - indexed for MEDLINE]

Development of biodegradable nanocarriers loaded with a monoclonal antibody.

Tue, 02/24/2015 - 3:30am

Development of biodegradable nanocarriers loaded with a monoclonal antibody.

Int J Mol Sci. 2015;16(2):3990-5

Authors: Gdowski A, Ranjan A, Mukerjee A, Vishwanatha J

Abstract
Treatments utilizing monoclonal antibody therapeutics against intracellular protein-protein interactions in cancer cells have been hampered by several factors, including poor intracellular uptake and rapid lysosomal degradation. Our current work examines the feasibility of encapsulating monoclonal antibodies within poly(lactic-co-glycolic acid) (PLGA) nanoparticles using a water/oil/water double emulsion solvent evaporation technique. This method can be used to prepare protective polymeric nanoparticles for transporting functional antibodies to the cytoplasmic compartment of cancer cells. Nanoparticles were formulated and then characterized using a number of physical and biological parameters. The average nanoparticle size ranged from 221 to 252 nm with a low polydispersity index. Encapsulation efficiency of 16%-22% and antibody loading of 0.3%-1.12% were observed. The antibody molecules were released from the nanoparticles in a sustained manner and upon release maintained functionality. Our studies achieved successful formulation of antibody loaded polymeric nanoparticles, thus indicating that a PLGA-based antibody nanoformulation is a promising intracellular delivery vehicle for a large number of new intracellular antibody targets in cancer cells.

PMID: 25690029 [PubMed - in process]

Elephant (Elephas maximus) Health and Management in Asia: Variations in Veterinary Perspectives.

Thu, 02/19/2015 - 3:29am
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Elephant (Elephas maximus) Health and Management in Asia: Variations in Veterinary Perspectives.

Vet Med Int. 2015;2015:614690

Authors: Miller D, Jackson B, Riddle HS, Stremme C, Schmitt D, Miller T

Abstract
There is a need to identify strategic investments in Asian elephant (Elephas maximus) health that will yield maximal benefits for overall elephant health and conservation. As an exploratory first step, a survey was administered to veterinarians from Asian elephant range countries at a workshop and via email to help prioritize health-related concerns that will mostly benefit elephants. Responses were received from 45 veterinarians from eight countries that had a range of experience with captive and wild elephants. The occurrence of medical conditions and responses to treatment varied among responses. However, injuries, parasitism, and gastrointestinal disease were reported as the most common syndromes responsible for elephant morbidity, whereas injury and infectious disease not due to parasitism were the most commonly reported sources of elephant mortality. Substandard nutrition, water quality and quantity deficiencies, and inadequate or absent shelter were among the factors listed as barriers to optimal elephant health. While this survey's results do not support definitive conclusions, they can be used to identify where and how subsequent investigations should be directed. Rigorous assessment of the relative costs and benefits of available options is required to ensure that investments in individual and population health yield the maximal benefits for elephants.

PMID: 25688328 [PubMed]

In reply to 'False-positive Xpert(®) MTB/RIF assays in previously treated patients'

Wed, 02/18/2015 - 3:30am

In reply to 'False-positive Xpert(®) MTB/RIF assays in previously treated patients'

Int J Tuberc Lung Dis. 2015 Mar;19(3):366-367

Authors: Steingart KR, Schiller I, Dendukuri N, Lalli M, Houben R, Churchyard G, White RG, Hoger S, Lykens K, Beavers S, Katz D, Miller T, Verma S, Verma G, Singh DV, Mokta J, Negi RS, Jhobta A, Kanga A, Flores-Suárez LF, Rivera LM, Rosales RM, Ruiz N, Saldaña RB

PMID: 25686149 [PubMed - as supplied by publisher]

Modeling cardiac arrest and resuscitation in the domestic pig.

Wed, 02/18/2015 - 3:30am

Modeling cardiac arrest and resuscitation in the domestic pig.

World J Crit Care Med. 2015 Feb 4;4(1):1-12

Authors: Cherry BH, Nguyen AQ, Hollrah RA, Olivencia-Yurvati AH, Mallet RT

Abstract
Cardiac arrest remains a leading cause of death and permanent disability worldwide. Although many victims are initially resuscitated, they often succumb to the extensive ischemia-reperfusion injury inflicted on the internal organs, especially the brain. Cardiac arrest initiates a complex cellular injury cascade encompassing reactive oxygen and nitrogen species, Ca(2+) overload, ATP depletion, pro- and anti-apoptotic proteins, mitochondrial dysfunction, and neuronal glutamate excitotoxity, which injures and kills cells, compromises function of internal organs and ignites a destructive systemic inflammatory response. The sheer complexity and scope of this cascade challenges the development of experimental models of and effective treatments for cardiac arrest. Many experimental animal preparations have been developed to decipher the mechanisms of damage to vital internal organs following cardiac arrest and cardiopulmonary resuscitation (CPR), and to develop treatments to interrupt the lethal injury cascades. Porcine models of cardiac arrest and resuscitation offer several important advantages over other species, and outcomes in this large animal are readily translated to the clinical setting. This review summarizes porcine cardiac arrest-CPR models reported in the literature, describes clinically relevant phenomena observed during cardiac arrest and resuscitation in pigs, and discusses numerous methodological considerations in modeling cardiac arrest/CPR. Collectively, published reports show the domestic pig to be a suitable large animal model of cardiac arrest which is responsive to CPR, defibrillatory countershocks and medications, and yields extensive information to foster advances in clinical treatment of cardiac arrest.

PMID: 25685718 [PubMed]

Nanofluidity of fatty acid hydrocarbon chains as monitored by benchtop time-domain nuclear magnetic resonance.

Tue, 02/17/2015 - 3:30am
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Nanofluidity of fatty acid hydrocarbon chains as monitored by benchtop time-domain nuclear magnetic resonance.

Biochemistry. 2014 Dec 9;53(48):7515-22

Authors: Robinson MD, Cistola DP

Abstract
The functional properties of lipid-rich assemblies such as serum lipoproteins, cell membranes, and intracellular lipid droplets are modulated by the fluidity of the hydrocarbon chain environment. Existing methods for monitoring hydrocarbon chain fluidity include fluorescence, electron spin resonance, and nuclear magnetic resonance (NMR) spectroscopy; each possesses advantages and limitations. Here we introduce a new approach based on benchtop time-domain (1)H NMR relaxometry (TD-NMR). Unlike conventional NMR spectroscopy, TD-NMR does not rely on the chemical shift resolution made possible by homogeneous, high-field magnets and Fourier transforms. Rather, it focuses on a multiexponential analysis of the time decay signal. In this study, we investigated a series of single-phase fatty acid oils, which allowed us to correlate (1)H spin-spin relaxation time constants (T2) with experimental measures of sample fluidity, as obtained using a viscometer. Remarkably, benchtop TD-NMR at 40 MHz was able to resolve two to four T2 components in biologically relevant fatty acids, assigned to nanometer-scale domains in different segments of the hydrocarbon chain. The T2 values for each domain were exquisitely sensitive to hydrocarbon chain structure; the largest values were observed for pure fatty acids or mixtures with the highest cis-double bond content. Moreover, the T2 values for each domain exhibited positive linear correlations with fluidity. The TD-NMR T2 and fluidity measurements appear to be monitoring the same underlying phenomenon: variations in hydrocarbon chain packing. The results from this study validate the use of benchtop TD-NMR T2 as a nanofluidity meter and demonstrate its potential for probing nanofluidity in other systems of biological interest.

PMID: 25409529 [PubMed - indexed for MEDLINE]

The spatial distribution of actin and mechanical cycle of myosin are different in right and left ventricles of healthy mouse hearts.

Tue, 02/17/2015 - 3:30am
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The spatial distribution of actin and mechanical cycle of myosin are different in right and left ventricles of healthy mouse hearts.

Biochemistry. 2014 Dec 9;53(48):7641-9

Authors: Nagwekar J, Duggal D, Rich R, Raut S, Fudala R, Gryczynski I, Gryczynski Z, Borejdo J

Abstract
The contraction of the right ventricle (RV) expels blood into the pulmonary circulation, and the contraction of the left ventricle (LV) pumps blood into the systemic circulation through the aorta. The respective afterloads imposed on the LV and RV by aortic and pulmonary artery pressures create very different mechanical requirements for the two ventricles. Indeed, differences have been observed in the contractile performance between left and right ventricular myocytes in dilated cardiomyopathy, in congestive heart failure, and in energy usage and speed of contraction at light loads in healthy hearts. In spite of these functional differences, it is commonly believed that the right and left ventricular muscles are identical because there were no differences in stress development, twitch duration, work performance, or power among the RV and LV in dogs. This report shows that on a mesoscopic scale [when only a few molecules are studied (here three to six molecules of actin) in ex vivo ventricular myofibrils], the two ventricles in rigor differ in the degree of orientational disorder of actin within in filaments and during contraction in the kinetics of the cross-bridge cycle.

PMID: 25488019 [PubMed - indexed for MEDLINE]

Pharmacology, benefits, unaddressed questions, and pragmatic issues of the newer oral anticoagulants for stroke prophylaxis in non-valvular atrial fibrillation and proposal of a management algorithm.

Sat, 02/14/2015 - 3:32am
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Pharmacology, benefits, unaddressed questions, and pragmatic issues of the newer oral anticoagulants for stroke prophylaxis in non-valvular atrial fibrillation and proposal of a management algorithm.

Int J Cardiol. 2014 Jul 1;174(3):471-83

Authors: Rosanio S, Keylani AM, D'Agostino DC, DeLaughter CM, Vitarelli A

Abstract
This systematic review aims to provide an update on pharmacology, efficacy and safety of the newer oral direct thrombin and factor Xa inhibitors, which have emerged for the first time in ~60 years as cogent alternatives to warfarin for stroke prophylaxis in non-valvular atrial fibrillation. We also discuss on four of the most common clinical scenarios with several unsolved questions and areas of uncertainty that may play a role in physicians' reluctance to prescribe the newer oral anticoagulants such as 1) patients with renal failure; 2) the elderly; 3) patients presenting with atrial fibrillation and acute coronary syndromes and/or undergoing coronary stenting; and 4) patients planning to receive AF ablation with the use of pulmonary vein isolation. New aspects presented in current guidelines are covered and we also propose an evidence-based anticoagulation management algorithm.

PMID: 24814537 [PubMed - indexed for MEDLINE]

A review of creatine supplementation in age-related diseases: more than a supplement for athletes.

Fri, 02/13/2015 - 3:30am
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A review of creatine supplementation in age-related diseases: more than a supplement for athletes.

F1000Res. 2014;3:222

Authors: Smith RN, Agharkar AS, Gonzales EB

Abstract
Creatine is an endogenous compound synthesized from arginine, glycine and methionine. This dietary supplement can be acquired from food sources such as meat and fish, along with athlete supplement powders. Since the majority of creatine is stored in skeletal muscle, dietary creatine supplementation has traditionally been important for athletes and bodybuilders to increase the power, strength, and mass of the skeletal muscle. However, new uses for creatine have emerged suggesting that it may be important in preventing or delaying the onset of neurodegenerative diseases associated with aging. On average, 30% of muscle mass is lost by age 80, while muscular weakness remains a vital cause for loss of independence in the elderly population. In light of these new roles of creatine, the dietary supplement's usage has been studied to determine its efficacy in treating congestive heart failure, gyrate atrophy, insulin insensitivity, cancer, and high cholesterol. In relation to the brain, creatine has been shown to have antioxidant properties, reduce mental fatigue, protect the brain from neurotoxicity, and improve facets/components of neurological disorders like depression and bipolar disorder. The combination of these benefits has made creatine a leading candidate in the fight against age-related diseases, such as Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, long-term memory impairments associated with the progression of Alzheimer's disease, and stroke. In this review, we explore the normal mechanisms by which creatine is produced and its necessary physiology, while paying special attention to the importance of creatine supplementation in improving diseases and disorders associated with brain aging and outlining the clinical trials involving creatine to treat these diseases.

PMID: 25664170 [PubMed]

Angiotensin II induces membrane trafficking of natively expressed transient receptor potential vanilloid type 4 channels in hypothalamic 4B cells.

Fri, 02/13/2015 - 3:30am
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Angiotensin II induces membrane trafficking of natively expressed transient receptor potential vanilloid type 4 channels in hypothalamic 4B cells.

Am J Physiol Regul Integr Comp Physiol. 2014 Oct 15;307(8):R945-55

Authors: Saxena A, Bachelor M, Park YH, Carreno FR, Nedungadi TP, Cunningham JT

Abstract
Transient receptor potential vanilloid family type 4 (TRPV4) channels are expressed in central neuroendocrine neurons and have been shown to be polymodal in other systems. We previously reported that in the rodent, a model of dilutional hyponatremia associated with hepatic cirrhosis, TRPV4 expression is increased in lipid rafts from the hypothalamus and that this effect may be angiotensin dependent. In this study, we utilized the immortalized neuroendocrine rat hypothalamic 4B cell line to more directly test the effects of angiotensin II (ANG II) on TRPV4 expression and function. Our results demonstrate the expression of corticotropin-releasing factor (CRF) transcripts, for sex-determining region Y (SRY) (male genotype), arginine vasopressin (AVP), TRPV4, and ANG II type 1a and 1b receptor in 4B cells. After a 1-h incubation in ANG II (100 nM), 4B cells showed increased TRPV4 abundance in the plasma membrane fraction, and this effect was prevented by the ANG II type 1 receptor antagonist losartan (1 μM) and by a Src kinase inhibitor PP2 (10 μM). Ratiometric calcium imaging experiments demonstrated that ANG II incubation potentiated TRPV4 agonist (GSK 1016790A, 20 nM)-induced calcium influx (control 18.4 ± 2.8% n = 5 and ANG II 80.5 ± 2.4% n = 5). This ANG II-induced increase in calcium influx was also blocked by 1 μM losartan and 10 μM PP2 (losartan 26.4 ± 3.8% n = 5 and PP2 19.7 ± 3.9% n = 5). Our data suggests that ANG II can increase TRPV4 channel membrane expression in 4B cells through its action on AT1R involving a Src kinase pathway.

PMID: 25080500 [PubMed - indexed for MEDLINE]

Exosome-associated hepatitis C virus in cell cultures and patient plasma.

Fri, 02/13/2015 - 3:30am
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Exosome-associated hepatitis C virus in cell cultures and patient plasma.

Biochem Biophys Res Commun. 2014 Dec 12;455(3-4):218-22

Authors: Liu Z, Zhang X, Yu Q, He JJ

Abstract
Hepatitis C virus (HCV) infects its target cells in the form of cell-free viruses and through cell-cell contact. Here we report that HCV is associated with exosomes. Using highly purified exosomes and transmission electron microscopic imaging, we demonstrated that HCV occurred in both exosome-free and exosome-associated forms. Exosome-associated HCV was infectious and resistant to neutralization by an anti-HCV neutralizing antibody. There were more exosome-associated HCV than exosome-free HCV detected in the plasma of HCV-infected patients. These results suggest exosome-associated HCV as an alternative form for HCV infection and transmission.

PMID: 25449270 [PubMed - indexed for MEDLINE]

The Critical Need to Promote Research of Aging and Aging-related Diseases to Improve Health and Longevity of the Elderly Population.

Wed, 02/11/2015 - 3:31am
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The Critical Need to Promote Research of Aging and Aging-related Diseases to Improve Health and Longevity of the Elderly Population.

Aging Dis. 2015 Feb;6(1):1-5

Authors: Jin K, Simpkins JW, Ji X, Leis M, Stambler I

Abstract
Due to the aging of the global population and the derivative increase in aging-related non-communicable diseases and their economic burden, there is an urgent need to promote research on aging and aging-related diseases as a way to improve healthy and productive longevity for the elderly population. To accomplish this goal, we advocate the following policies: 1) Increasing funding for research and development specifically directed to ameliorate degenerative aging processes and to extend healthy and productive lifespan for the population; 2) Providing a set of incentives for commercial, academic, public and governmental organizations to foster engagement in such research and development; and 3) Establishing and expanding coordination and consultation structures, programs and institutions involved in aging-related research, development and education in academia, industry, public policy agencies and at governmental and supra-governmental levels.

PMID: 25657847 [PubMed]

HIV-1 Tat Alters Neuronal Autophagy by Modulating Autophagosome Fusion to the Lysosome: Implications for HIV-Associated Neurocognitive Disorders.

Sat, 02/07/2015 - 3:33am

HIV-1 Tat Alters Neuronal Autophagy by Modulating Autophagosome Fusion to the Lysosome: Implications for HIV-Associated Neurocognitive Disorders.

J Neurosci. 2015 Feb 4;35(5):1921-38

Authors: Fields J, Dumaop W, Elueteri S, Campos S, Serger E, Trejo M, Kosberg K, Adame A, Spencer B, Rockenstein E, He JJ, Masliah E

Abstract
Antiretroviral therapy has increased the life span of HIV+ individuals; however, HIV-associated neurocognitive disorder (HAND) occurrence is increasing in aging HIV patients. Previous studies suggest HIV infection alters autophagy function in the aging CNS and HIV-1 proteins affect autophagy in monocyte-derived cells. Despite these findings, the mechanisms leading to dysregulated autophagy in the CNS remain unclear. Here we sought to determine how HIV Tat dysregulates autophagy in neurons. Tat caused a dose-dependent decrease in autophagosome markers, microtubule-associated protein-1 light chain β II (LC3II), and sequestosome 1(SQSTM1), in a membrane-enriched fraction, suggesting Tat increases autophagic degradation. Bafilomycin A1 increased autophagosome number, LC3II, and SQSTM1 accumulation; Tat cotreatment diminished this effect. Tat had no effect when 3-methyladenine or knockdown of beclin 1 blocked early stages of autophagy. Tat increased numbers of LC3 puncta and resulted in the formation of abnormal autophagosomes in vitro. Likewise, in vivo studies in GFAP-Tat tg mice showed increased autophagosome accumulation in neurons, altered LC3II levels, and neurodegeneration. These effects were reversed by rapamycin treatment. Tat colocalized with autophagosome and lysosomal markers and enhanced the colocalization of autophagosome with lysosome markers. Furthermore, co-IP studies showed that Tat interacts with lysosomal-associated membrane protein 2A (LAMP2A) in vitro and in vivo, and LAMP2A overexpression reduces Tat-induced neurotoxicity. Hence, Tat protein may induce autophagosome and lysosome fusion through interaction with LAMP2A leading to abnormal neuronal autophagy function and dysregulated degradation of critical intracellular components. Therapies targeting Tat-mediated autophagy alterations may decrease neurodegeneration in aging patients with HAND.

PMID: 25653352 [PubMed - in process]

Autonomic neural control of heart rate during dynamic exercise: revisited.

Fri, 02/06/2015 - 3:30am
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Autonomic neural control of heart rate during dynamic exercise: revisited.

J Physiol. 2014 Jun 15;592(Pt 12):2491-500

Authors: White DW, Raven PB

Abstract
UNLABELLED: The accepted model of autonomic control of heart rate (HR) during dynamic exercise indicates that the initial increase is entirely attributable to the withdrawal of parasympathetic nervous system (PSNS) activity and that subsequent increases in HR are entirely attributable to increases in cardiac sympathetic activity. In the present review, we sought to re-evaluate the model of autonomic neural control of HR in humans during progressive increases in dynamic exercise workload. We analysed data from both new and previously published studies involving baroreflex stimulation and pharmacological blockade of the autonomic nervous system. Results indicate that the PSNS remains functionally active throughout exercise and that increases in HR from rest to maximal exercise result from an increasing workload-related transition from a 4 : 1 vagal-sympathetic balance to a 4 : 1 sympatho-vagal balance. Furthermore, the beat-to-beat autonomic reflex control of HR was found to be dependent on the ability of the PSNS to modulate the HR as it was progressively restrained by increasing workload-related sympathetic nerve activity.
IN CONCLUSION: (i) increases in exercise workload-related HR are not caused by a total withdrawal of the PSNS followed by an increase in sympathetic tone; (ii) reciprocal antagonism is key to the transition from vagal to sympathetic dominance, and (iii) resetting of the arterial baroreflex causes immediate exercise-onset reflexive increases in HR, which are parasympathetically mediated, followed by slower increases in sympathetic tone as workloads are increased.

PMID: 24756637 [PubMed - indexed for MEDLINE]

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