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1.
AIDS Care ; 35(8): 1164-1172, 2023 08.
Article in English | MEDLINE | ID: mdl-33443450

ABSTRACT

Pain is a highly prevalent and burdensome symptom among people with HIV (PWH). This study aims to identify how the experience of living with HIV and chronic pain influences pain beliefs, health-seeking and pain management. Thirty-nine purposively sampled PWH with chronic pain (sample characteristics = 61% women, 79% Black, Asian and minority ethnic groups, 18% men who have sex with men, 45-54 median age category) participated in focus groups in London. Focus groups were co-facilitated with community members. Transcripts wereanalysed using a thematic approach. Findings revealed that HIV stigma, fractured care pathways, and general practitioners' lack of HIV training are barriers to supported pain management. Unaddressed pain results in poorer mental health and reduced quality of life, which has important clinical implications for HIV treatment adherence. Creating HIV-specific pain resources, activating social networks, and pain self-management techniques are potential solutions. Person-centred assessment and HIV training is needed to help clinicians identify PWH with chronic pain. Clear guidelines need to be developed to identify which health service providers are responsible for chronic pain management in PWH. This study generated a refined version of the Fear Avoidance Model that introduces a dimension of HIV-specific behaviours that impact PWHs seeking chronic pain management.


Subject(s)
Chronic Pain , HIV Infections , Sexual and Gender Minorities , Male , Humans , Female , Homosexuality, Male , Chronic Pain/therapy , Pain Management , Quality of Life , HIV Infections/complications , HIV Infections/therapy , HIV Infections/diagnosis
2.
Science ; 361(6400): 406-411, 2018 07 27.
Article in English | MEDLINE | ID: mdl-30049881

ABSTRACT

Germline mutations in STK11, which encodes the tumor suppressor liver kinase B1 (LKB1), promote Peutz-Jeghers syndrome (PJS), a cancer predisposition syndrome characterized by the development of gastrointestinal (GI) polyps. Here, we report that heterozygous deletion of Stk11 in T cells (LThet mice) is sufficient to promote GI polyposis. Polyps from LThet mice, Stk11+/- mice, and human PJS patients display hallmarks of chronic inflammation, marked by inflammatory immune-cell infiltration, signal transducer and activator of transcription 3 (STAT3) activation, and increased expression of inflammatory factors associated with cancer progression [interleukin 6 (IL-6), IL-11, and CXCL2]. Targeting either T cells, IL-6, or STAT3 signaling reduced polyp growth in Stk11+/- animals. Our results identify LKB1-mediated inflammation as a tissue-extrinsic regulator of intestinal polyposis in PJS, suggesting possible therapeutic approaches by targeting deregulated inflammation in this disease.


Subject(s)
Adenomatous Polyps/genetics , Peutz-Jeghers Syndrome/genetics , Protein Serine-Threonine Kinases/genetics , Stomach Neoplasms/genetics , T-Lymphocytes/immunology , AMP-Activated Protein Kinases , Adenomatous Polyps/immunology , Adenomatous Polyps/pathology , Animals , Chemokine CXCL2/genetics , Gene Deletion , Gene Expression , Humans , Inflammation/genetics , Inflammation/immunology , Inflammation/pathology , Interleukin-11/genetics , Interleukin-6/genetics , Mice , Mice, Inbred C57BL , Mice, Mutant Strains , Peutz-Jeghers Syndrome/immunology , Peutz-Jeghers Syndrome/pathology , STAT3 Transcription Factor/metabolism , Signal Transduction , Stomach Neoplasms/immunology , Stomach Neoplasms/pathology
3.
IBRO Rep ; 1: 46-53, 2016 Dec.
Article in English | MEDLINE | ID: mdl-30135927

ABSTRACT

The storage and use of glycogen, the main energy reserve in the brain, is a metabolic feature of astrocytes. Glycogen synthesis is regulated by Protein Targeting to Glycogen (PTG), a member of specific glycogen-binding subunits of protein phosphatase-1 (PPP1). It positively regulates glycogen synthesis through de-phosphorylation of both glycogen synthase (activation) and glycogen phosphorylase (inactivation). In cultured astrocytes, PTG mRNA levels were previously shown to be enhanced by the neurotransmitter noradrenaline. To achieve further insight into the role of PTG in the regulation of astrocytic glycogen, its levels of expression were manipulated in primary cultures of mouse cortical astrocytes using adenovirus-mediated overexpression of tagged-PTG or siRNA to downregulate its expression. Infection of astrocytes with adenovirus led to a strong increase in PTG expression and was associated with massive glycogen accumulation (>100 fold), demonstrating that increased PTG expression is sufficient to induce glycogen synthesis and accumulation. In contrast, siRNA-mediated downregulation of PTG resulted in a 2-fold decrease in glycogen levels. Interestingly, PTG downregulation strongly impaired long-term astrocytic glycogen synthesis induced by insulin or noradrenaline. Finally, these effects of PTG downregulation on glycogen metabolism could also be observed in cultured astrocytes isolated from PTG-KO mice. Collectively, these observations point to a major role of PTG in the regulation of glycogen synthesis in astrocytes and indicate that conditions leading to changes in PTG expression will directly impact glycogen levels in this cell type.

4.
Transpl Infect Dis ; 17(1): 94-7, 2015 Feb.
Article in English | MEDLINE | ID: mdl-25537527

ABSTRACT

Eumycetoma is a chronic infection of the skin and subcutaneous tissue caused by filamentous fungi, which usually occurs in tropical or subtropical countries. We report a case of an immunocompromised patient presenting with presumed eumycetoma in the United States and his subsequent treatment with voriconazole. The use of voriconazole and liposomal amphotericin B halted the progression and allowed gradual resolution of the infection. The patient will require close monitoring and long-term therapy with voriconazole to obtain a clinical cure. Voriconazole and liposomal amphotericin B are potential initial treatment options, with long-term voriconazole maintenance therapy, for an Aspergillus-induced eumycetoma.


Subject(s)
Antifungal Agents/therapeutic use , Aspergillosis/drug therapy , Aspergillus/drug effects , Hematopoietic Stem Cell Transplantation/adverse effects , Immunocompromised Host/immunology , Mycetoma/drug therapy , Aged , Amphotericin B/therapeutic use , Aspergillosis/diagnosis , Aspergillosis/microbiology , Fungi , Humans , Male , Mycetoma/diagnosis , Mycetoma/microbiology , United States , Voriconazole/therapeutic use
5.
AJNR Am J Neuroradiol ; 33(9): 1797-803, 2012 Oct.
Article in English | MEDLINE | ID: mdl-22538073

ABSTRACT

BACKGROUND AND PURPOSE: GM volume, WMH volume, and FA are each associated with cognition; however, few studies have detected whether these 3 different types of MR imaging measurements exert independent or additive effects on cognitive performance. To detect their extent of contribution to cognitive performance, we explored the independent and additive contributions of GM atrophy, white matter injury, and white matter integrity to cognition in elderly patients. MATERIALS AND METHODS: Two hundred and 9 elderly patients participated in the study: 97 were CN adults, 65 had MCI, and 47 had dementia. We measured GM on T1-weighted MR imaging, WMH on FLAIR, and FA on DTI, along with psychometrically matched measures of 4 domains of cognitive performance, including semantic memory, episodic memory, executive function, and spatial abilities. RESULTS: As expected, patients with dementia performed significantly more poorly in all 4 cognitive domains, whereas patients with MCI performed generally less poorly than dementia patients, though considerable overlap in performance was present across groups. GM, FA, and WMH each differed significantly between diagnostic groups and were associated with cognitive measures. In multivariate models that included all 3 MR imaging measures (GM, WMH, and FA), GM volume was the strongest determinant of cognitive performance. CONCLUSIONS: These results strongly suggest that MR imaging measures of GM are more closely associated with cognitive function than WM measures across a broad range of cognitive and functional impairment.


Subject(s)
Aging/physiology , Cognition/physiology , Dementia/diagnosis , Dementia/physiopathology , Magnetic Resonance Imaging/methods , Nerve Fibers, Myelinated/physiology , Neurons/cytology , Aged , Aged, 80 and over , Aging/pathology , Brain/cytology , Brain/physiology , Dementia/pathology , Female , Humans , Male , Middle Aged , Nerve Fibers, Myelinated/pathology , Neurons/physiology
6.
Phys Rev Lett ; 104(7): 074501, 2010 Feb 19.
Article in English | MEDLINE | ID: mdl-20366890

ABSTRACT

The first observation of fast and slow magnetocoriolis (MC) waves in a laboratory experiment is reported. Rotating nonaxisymmetric modes arising from a magnetized turbulent Taylor-Couette flow of liquid metal are identified as the fast and slow MC waves by the dependence of the rotation frequency on the applied field strength. The observed slow MC wave is damped but the observation provides a means for predicting the onset of the magnetorotational instability.

7.
Mar Pollut Bull ; 58(12): 1780-6, 2009 Dec.
Article in English | MEDLINE | ID: mdl-19767018

ABSTRACT

Oyster (Saccostrea commercialis) biomonitoring, assessment of oyster and gastropod (Bembicium auratum) abundance, and gastropod imposex were used to measure the significance of tributyltin (TBT) contamination in an intertidal mangrove forest. We studied the bioavailable levels of TBT in oysters approximately 1 km downstream and 2 km upstream from a TBT waste disposal site. We found observable declines in the abundance of oysters and gastropods correlated with the bioavailable TBT and these findings were confirmed by mapping oyster beds. Oyster cover near the disposal site ranged from 0% to 5% while downstream and upstream populations ranged in cover from 25-50% to 5-25%, respectively. Similarly, gastropod abundances at the disposal site were only 7% of the downstream population and 17% of the upstream population. Imposex was present in 90% of female B. auratum from populations near the disposal site but this effect declined more sharply than the population level effects.


Subject(s)
Environmental Monitoring/methods , Gastropoda/drug effects , Ostreidae/drug effects , Rivers/chemistry , Trialkyltin Compounds/toxicity , Animals , Disorders of Sex Development/chemically induced , Female , Gastropoda/metabolism , Geologic Sediments/chemistry , New South Wales , Ostreidae/metabolism , Trialkyltin Compounds/analysis , Trialkyltin Compounds/metabolism
8.
J Food Sci ; 74(2): N23-9, 2009 Mar.
Article in English | MEDLINE | ID: mdl-19323765

ABSTRACT

The association of triclosan (TCS), a widely used hydrophobic compound, to the bovine casein micelle is investigated in this study. The use of high-pressure homogenization (HPH) at 0, 100, 200, and 300 MPa was introduced as a method for the dissociation of casein micelles in a skim milk/ethanol solution (1: 1, v/v) in the presence of TCS at 20, 80, and 160 mg/L where ethanol evaporation served as the final step for TCS association to caseins. The majority of TCS (over 80%) was associated with the caseins regardless of initial TCS concentration or applied pressure. TCS association to caseins was enhanced by 30% with continued pressurization to 300 MPa. Micellar dissociation and reassociation was found to be an irreversible process as evidenced by microscopy images. Pressurization to 300 MPa resulted in the formation of an integrated protein network of casein proteins and noncovalently linked whey proteins where the solubility of TCS was enhanced up to 40 times its reported water solubility at the highest initial TCS level of 160 mg/L. Reformed micelles exhibited Newtonian flow behavior at all pressure levels. This study provides evidence for the solubility enhancing quality of TCS through the solvent-mediated pressure/shear-induced dissociation of casein proteins.


Subject(s)
Caseins/metabolism , Triclosan/metabolism , Animals , Caseins/isolation & purification , Cattle , Chromatography, High Pressure Liquid , Micelles , Milk/chemistry , Milk Proteins/metabolism , Solvents , Whey Proteins
9.
Br J Pharmacol ; 154(7): 1400-13, 2008 Aug.
Article in English | MEDLINE | ID: mdl-18552866

ABSTRACT

The zebrafish is a well-established model organism used in developmental biology. In the last decade, this technology has been extended to the generation of high-value knowledge on safety risks of novel drugs. Indeed, the larval zebrafish appear to combine advantages of whole organism phenotypic assays and those (rapid production of results with minimal resource engagement) of in vitro high-throughput screening techniques. Thus, if appropriately evaluated, it can offer undeniable advantages in drug discovery for identification of target and off-target effects. Here, we review some applications of zebrafish to identify potential safety liabilities, particularly before lead/candidate selection. For instance, zebrafish cardiovascular system can be used to reveal decreases in heart rate and atrial-ventricular dissociation, which may signal human ether-a-go-go-related gene (hERG) channel blockade. Another main area of interest is the CNS, where zebrafish behavioural assays have been and are further being developed into screening platforms for assessment of locomotor activity, convulsant and proconvulsant liability, cognitive impairment, drug dependence potential and impaired visual and auditory functions. Zebrafish also offer interesting possibilities for evaluating effects on bone density and gastrointestinal function. Furthermore, available knowledge of the renal system in larval zebrafish can allow identification of potential safety issues of drug candidates on this often neglected area in early development platforms. Although additional validation is certainly needed, the zebrafish is emerging as a versatile in vivo animal model to identify off-target effects that need investigation and further clarification early in the drug discovery process to reduce the current, high degree of attrition in development.


Subject(s)
Drug-Related Side Effects and Adverse Reactions , Models, Animal , Zebrafish , Animals , Drug Delivery Systems , Drug Design , Drug Evaluation, Preclinical/methods , Larva/metabolism , Pharmacology/methods
10.
Arch Environ Contam Toxicol ; 54(2): 292-308, 2008 Feb.
Article in English | MEDLINE | ID: mdl-17768590

ABSTRACT

The concentrations of the metals cadmium, copper, mercury, lead, silver, selenium and zinc were measured in the muscle and gonad tissues of five species of fish, yellowfin bream (Acanthopagrus australis), silverbiddy (Gerres subfasciatus) and trumpeter whiting (Sillago maculata), southern log finned goby (Favonigobious lateralis), and the halfbridled goby (Arenigobius frenatus) from the contaminated Lake Macquarie NSW and three relatively uncontaminated reference estuaries, Wallis Lake, Port Stephens, and St. Georges Basin NSW. Fish from Lake Macquarie were found to have elevated concentrations of selenium, lead, cadmium, and zinc in one or both of these tissues in these species. Increased concentrations relative to background concentrations were most often observed at Cockle Bay, the site with the highest concentrations of these metals in sediments. The degree to which fish accumulated metals appeared to be related to life history characteristics of the species, with sediment-dwelling fish showing the greatest propensity to accumulate metals.


Subject(s)
Arsenic/metabolism , Fishes/metabolism , Metals, Heavy/metabolism , Selenium/metabolism , Water Pollutants, Chemical/metabolism , Animals , Environmental Monitoring , Female , Fresh Water , Muscles/metabolism , New South Wales , Ovary/metabolism
11.
J Neuroimmunol ; 190(1-2): 8-17, 2007 Oct.
Article in English | MEDLINE | ID: mdl-17714795

ABSTRACT

Clusterin is a protein involved in multiple biological events, including neuronal cytoprotection, membrane recycling and regulation of complement-mediated membrane attack after injury. We investigated the effect of recombinant human clusterin in preclinical models of peripheral neuropathies. Daily treatment with clusterin accelerated the recovery of nerve motor evoked potential parameters after sciatic nerve injury. Prophylactic or therapeutic treatment of experimental autoimmune neuritis rats with clusterin also accelerated the rate of recovery from the disease, associated with remyelination of demyelinated nerve fibers. These data demonstrate that clusterin is capable of ameliorating clinical, neurophysiological and pathological signs in models of peripheral neuropathies.


Subject(s)
Clusterin/pharmacology , Nerve Growth Factors/pharmacology , Nerve Regeneration/drug effects , Peripheral Nerves/drug effects , Peripheral Nervous System Diseases/drug therapy , Animals , Clusterin/immunology , Clusterin/therapeutic use , Cytokines/drug effects , Cytokines/immunology , Cytokines/metabolism , Disease Models, Animal , Encephalomyelitis, Autoimmune, Experimental/drug therapy , Encephalomyelitis, Autoimmune, Experimental/immunology , Encephalomyelitis, Autoimmune, Experimental/physiopathology , Female , Hippocampus/immunology , Hippocampus/metabolism , Hippocampus/pathology , Mice , Mice, Inbred C57BL , Myelin Basic Protein/drug effects , Myelin Basic Protein/immunology , Myelin Basic Protein/metabolism , Myelin Sheath/drug effects , Myelin Sheath/immunology , Myelin Sheath/pathology , Nerve Growth Factors/immunology , Nerve Growth Factors/therapeutic use , Nerve Regeneration/immunology , Neurons/drug effects , Neurons/immunology , Neurons/pathology , Organ Culture Techniques , Peripheral Nerves/immunology , Peripheral Nerves/physiopathology , Peripheral Nervous System Diseases/immunology , Peripheral Nervous System Diseases/physiopathology , Recombinant Proteins/immunology , Recombinant Proteins/pharmacology , Recombinant Proteins/therapeutic use , Sciatic Neuropathy/drug therapy , Sciatic Neuropathy/immunology , Sciatic Neuropathy/physiopathology , Treatment Outcome
12.
J Clin Pharm Ther ; 32(4): 327-31, 2007 Aug.
Article in English | MEDLINE | ID: mdl-17635334

ABSTRACT

The treatment of chronic inflammatory conditions often involves a difficult balance between the benefits of disease modification and the risks attendant with the use of disease-modifying agents. Methotrexate is a useful and commonly used disease-modifying agent but has a particularly notable reputation for causing morbidity and mortality. We explore ways in which the safety of methotrexate prescribing may be improved. There has been considerable debate as to the whether some of the side-effects can be mitigated by co-prescription of folate with methotrexate. Whereas no definitive conclusion can yet be reached, evidence suggests that the improvement in side-effect profile is limited to fewer elevations of liver enzymes, but that this may be at the expense of decreased methotrexate efficacy. The question remains as to whether the improved tolerability more than compensates for the decreased efficacy or whether folic acid should be used in a more circumspect way. However, a very specific danger arises from the fact that methotrexate is prescribed once weekly for inflammatory conditions, leading to errors at both the prescription and patient level. We highlight simple ways of improving safety to decrease such errors.


Subject(s)
Antirheumatic Agents/adverse effects , Medication Errors/prevention & control , Methotrexate/adverse effects , Antirheumatic Agents/administration & dosage , Antirheumatic Agents/pharmacology , Arthritis, Rheumatoid/drug therapy , Drug Labeling , Drug Packaging , Drug Therapy, Combination , Folic Acid/pharmacology , Folic Acid/therapeutic use , Humans , Methotrexate/administration & dosage , Methotrexate/pharmacology , Polymyositis/drug therapy , Practice Patterns, Physicians' , Vitamin B Complex/pharmacology , Vitamin B Complex/therapeutic use
13.
Phys Rev Lett ; 98(14): 145002, 2007 Apr 06.
Article in English | MEDLINE | ID: mdl-17501282

ABSTRACT

Odd-parity rotating magnetic fields (RMFo) applied to mirror-configuration plasmas have produced average electron energies exceeding 200 eV at line-averaged electron densities of approximately 10(12) cm-3. These plasmas, sustained for over 10(3)tauAlfven, have low Coulomb collisionality, vc* triple bond L/lambdaC approximately 10(-3), where lambdaC is the Coulomb scattering mean free path and L is the plasma's characteristic half length. Divertors allow reduction of the electron-neutral collision frequency to values where the RMFo coupling indicates full penetration of the RMFo to the major axis.

14.
Mar Environ Res ; 64(1): 54-78, 2007 Jul.
Article in English | MEDLINE | ID: mdl-17306363

ABSTRACT

The benthic bivalve, Anadara trapezia, was collected from a 'clean' reference site and transplanted along a suspected trace metal contamination gradient in Lake Macquarie, NSW. At monthly intervals, Zn, Se, Cd and Pb concentrations were measured in the surficial sediments and whole tissues of the cockle as well as their physiological condition (Scope for Growth). Zinc, Cd and Pb concentrations in sediments decreased together, southward, with the highest concentrations in the Cockle Bay area, suggesting that this is the main source of contamination. Zinc, Cd and Pb concentrations were near or above [ANZECC/ARMCANZ, 2000. National water quality management strategy paper 4. Australian and New Zealand Guidelines for Fresh and Marine Water Quality, Australian and New Zealand Conservation Council and Agriculture and Resource Management Council of Australia and New Zealand. pp. 3.5.-1-3.5-10] sediment quality guidelines at Cockle Creek, Warners Bay and Koorooa Bay. Significant differences in trace metal concentrations could not be attributed to grain size or Fe concentration differences. Se concentrations were highest in fine grain Fe rich sediments of Whiteheads Lagoon, and likely to be associated with power generation operations. Trace metal concentrations did not vary significantly over time. Zinc, Cd and Pb concentrations in the tissues of A. trapezia followed a similar pattern to that of sediments. Zinc and Pb concentrations in cockles and sediments were highly correlated, indicating significant exposure-dose relationships. Selenium concentrations in the tissues of A. trapezia were higher after transplantation to the lake, however, Se concentrations were similar in all transplanted cockles, indicating that Se in contaminated sediments is not the major source of Se to organisms. There was a decline in the physiological condition of A. trapezia transplanted to Lake Macquarie after a 90-day-period with marked differences in clearance rates and respiration rates at some locations and absorption efficiencies at all locations. The mean Scope for Growth value at the most contaminated location, Cockle Bay, was markedly lower than at other locations. A significant Zn exposure-dose response relationship indicates that Zn bioaccumulation is occurring in response to sediment contamination. A significant Cd exposure-response relationship indicates that Cd may be influencing the health of cockles. Significant Pb exposure-dose, exposure-response and dose-response relationships indicate that Pb probably is affecting the health of cockles in Lake Macquarie. Therefore, Zn, Cd and Pb concentrations in sediments are likely to be affecting the health of cockles in Lake Macquarie.


Subject(s)
Arcidae/physiology , Environmental Exposure , Geologic Sediments/analysis , Metals, Heavy/metabolism , Selenium/physiology , Water Pollutants, Chemical/metabolism , Analysis of Variance , Animals , Arcidae/chemistry , Arcidae/metabolism , Dose-Response Relationship, Drug , Environmental Monitoring , Metals, Heavy/analysis , New South Wales , Selenium/analysis , Time Factors , Water Pollutants, Chemical/analysis
15.
Mar Environ Res ; 59(5): 453-72, 2005 Jun.
Article in English | MEDLINE | ID: mdl-15603769

ABSTRACT

Industrial activity since the 1890s and, more recently catchment development has resulted in significant metal contamination in Lake Macquarie, an estuary in New South Wales, Australia. This paper presents an analysis of metal concentrations in surface sediments from Lake Macquarie using normalisation models to estimate enrichment relative to natural background concentrations and by comparing concentrations with sediment quality guidelines (SQGs) and effects range median quotients to assess the potential for ecological harm. Of the 12 metals examined, cadmium, lead, mercury, selenium, silver and zinc were enriched in surface sediments throughout the lake. The greatest contamination was found in the north of the lake and, for selenium, also in areas adjacent to two power stations. Comparisons with SQGs and effects range median quotients found that sediments from a site in Cockle Bay had concentrations of metals with the highest likelihood of causing adverse effects on sediment associated biota, and that the likelihood adverse decreased with distance from Cockle Bay. Comparisons with historical sediment quality data indicated that there has been a marked reduction in surface metal concentrations throughout the lake over 15 years. Models could not be constructed for all metals due to low background concentrations. For most metals, simple linear regression models were adequate, but for selenium and arsenic a multiple regression model provided a better estimate of background concentrations. SQGs possibly overestimated effects for arsenic, which has naturally high concentrations in the lake and underestimated the potential for ecological effects in coarser sediments.


Subject(s)
Guidelines as Topic , Metals, Heavy/analysis , Models, Theoretical , Water Pollutants, Chemical/analysis , Environmental Monitoring , Geologic Sediments/chemistry , Industry , New South Wales , Reference Values
16.
J Biol Chem ; 276(43): 39959-67, 2001 Oct 26.
Article in English | MEDLINE | ID: mdl-11522787

ABSTRACT

In skeletal muscle both insulin and contractile activity are physiological stimuli for glycogen synthesis, which is thought to result in part from the dephosphorylation and activation of glycogen synthase (GS). PP1G/R(GL)(G(M)) is a glycogen/sarcoplasmic reticulum-associated type 1 phosphatase that was originally postulated to mediate insulin control of glycogen metabolism. However, we recently showed (Suzuki, Y., Lanner, C., Kim, J.-H., Vilardo, P. G., Zhang, H., Jie Yang, J., Cooper, L. D., Steele, M., Kennedy, A., Bock, C., Scrimgeour, A., Lawrence, J. C. Jr., L., and DePaoli-Roach, A. A. (2001) Mol. Cell. Biol. 21, 2683-2694) that insulin activates GS in muscle of R(GL)(G(M)) knockout (KO) mice similarly to the wild type (WT). To determine whether PP1G is involved in glycogen metabolism during muscle contractions, R(GL) KO and overexpressors (OE) were subjected to two models of contraction, in vivo treadmill running and in situ electrical stimulation. Both procedures resulted in a 2-fold increase in the GS -/+ glucose-6-P activity ratio in WT mice, but this response was completely absent in the KO mice. The KO mice, which also have a reduced GS activity associated with significantly reduced basal glycogen levels, exhibited impaired maximal exercise capacity, but contraction-induced activation of glucose transport was unaffected. The R(GL) OE mice are characterized by enhanced GS activity ratio and an approximately 3-4-fold increase in glycogen content in skeletal muscle. These animals were able to tolerate exercise normally. Stimulation of GS and glucose uptake following muscle contraction was not significantly different as compared with WT littermates. These results indicate that although PP1G/R(GL) is not necessary for activation of GS by insulin, it is essential for regulation of glycogen metabolism under basal conditions and in response to contractile activity, and may explain the reduced muscle glycogen content in the R(GL) KO mice, despite the normal insulin activation of GS.


Subject(s)
Carrier Proteins/metabolism , Glycogen Synthase/metabolism , Motor Activity/physiology , Muscle, Skeletal/physiology , Phosphoprotein Phosphatases/metabolism , Physical Conditioning, Animal/physiology , Physical Exertion/physiology , Animals , Biological Transport , Carrier Proteins/genetics , Electric Stimulation , Enzyme Activation , Exercise Tolerance/physiology , Glucose/metabolism , Glycogen/metabolism , Glycogen Phosphorylase/metabolism , Mice , Mice, Mutant Strains , Muscle Contraction/physiology , Phosphoprotein Phosphatases/genetics , Protein Phosphatase 1
17.
Arch Biochem Biophys ; 388(1): 135-45, 2001 Apr 01.
Article in English | MEDLINE | ID: mdl-11361130

ABSTRACT

The type I phosphatase associated with glycogen, PP1G, plays an important role in glycogen metabolism. PP1G is targeted to glycogen by the R(GL) subunit, which regulates the function of the enzyme. We report the cloning and characterization of the gene as well as the pattern of expression of the R(GL) subunit from mouse. The gene covers more than 37 kb, is composed of four exons and three introns, and codes for a 1089 residue polypeptide with a calculated molecular weight of 121,000. The amino acid sequence has 60% identity with the human and rabbit R(GL). The 5' flanking region of the gene contains a TATA box, c-Myc sites, and a potential cAMP-responsive element. Muscle specific motifs, such as MyoD and MEF-2, were also found. The A-T rich 3'-UTR contained several polyadenylation signals, two associated with poly(A) down-stream consensus motifs. ARE elements, which regulate mRNA stability, were dispersed throughout the 3'-UTR. Northern analysis of poly(A) mRNA from various murine tissues indicates a major transcript of 7.5 kb in skeletal muscle and heart. Western analysis demonstrates that R(GL) protein is present in skeletal and cardiac muscle from mouse, rat, and rabbit but not in L6 myoblasts, L6 myotubes, 3T3 L1 fibroblasts, 3T3 L1 or rat primary adipocytes, confirming that expression of the gene is specific to striated muscle. Analysis of skeletal muscle from rats made diabetic by streptozotocin treatment reveals that the level of R(GL) protein is the same as in control animals, indicating that expression is not regulated by insulin.


Subject(s)
Carrier Proteins/chemistry , Carrier Proteins/genetics , Muscles/enzymology , Phosphoprotein Phosphatases/chemistry , Phosphoprotein Phosphatases/genetics , 3' Untranslated Regions , Adipocytes/metabolism , Amino Acid Sequence , Animals , Base Sequence , Blotting, Northern , Blotting, Western , Cells, Cultured , Cloning, Molecular , Cyclic AMP/metabolism , DNA, Complementary/metabolism , DNA-Binding Proteins/metabolism , Exons , Gene Library , Humans , Insulin/metabolism , Introns , MEF2 Transcription Factors , Mice , Models, Genetic , Molecular Sequence Data , Muscle, Skeletal/metabolism , MyoD Protein/metabolism , Myogenic Regulatory Factors , Polymorphism, Genetic , Protein Biosynthesis , Protein Phosphatase 1 , Proto-Oncogene Proteins c-myc/metabolism , RNA, Messenger/metabolism , Rabbits , Rats , Rats, Sprague-Dawley , Sequence Homology, Amino Acid , Streptozocin/pharmacology , Tissue Distribution , Transcription Factors/metabolism , Transcription, Genetic
18.
Mol Cell Biol ; 21(8): 2683-94, 2001 Apr.
Article in English | MEDLINE | ID: mdl-11283248

ABSTRACT

The regulatory-targeting subunit (RGL), also called GM) of the muscle-specific glycogen-associated protein phosphatase PP1G targets the enzyme to glycogen where it modulates the activity of glycogen-metabolizing enzymes. PP1G/RGL has been postulated to play a central role in epinephrine and insulin control of glycogen metabolism via phosphorylation of RGL. To investigate the function of the phosphatase, RGL knockout mice were generated. Animals lacking RGL show no obvious defects. The RGL protein is absent from the skeletal and cardiac muscle of null mutants and present at approximately 50% of the wild-type level in heterozygotes. Both the level and activity of C1 protein are also decreased by approximately 50% in the RGL-deficient mice. In skeletal muscle, the glycogen synthase (GS) activity ratio in the absence and presence of glucose-6-phosphate is reduced from 0.3 in the wild type to 0.1 in the null mutant RGL mice, whereas the phosphorylase activity ratio in the absence and presence of AMP is increased from 0.4 to 0.7. Glycogen accumulation is decreased by approximately 90%. Despite impaired glycogen accumulation in muscle, the animals remain normoglycemic. Glucose tolerance and insulin responsiveness are identical in wild-type and knockout mice, as are basal and insulin-stimulated glucose uptakes in skeletal muscle. Most importantly, insulin activated GS in both wild-type and RGL null mutant mice and stimulated a GS-specific protein phosphatase in both groups. These results demonstrate that RGL is genetically linked to glycogen metabolism, since its loss decreases PP1 and basal GS activities and glycogen accumulation. However, PP1G/RGL is not required for insulin activation of GS in skeletal muscle, and rather another GS-specific phosphatase appears to be involved.


Subject(s)
Glycogen/metabolism , Insulin/pharmacology , Phosphoprotein Phosphatases/deficiency , Animals , Base Sequence , DNA Primers/genetics , Enzyme Activation/drug effects , Female , Glucose/metabolism , Glucose/pharmacology , Glycogen Synthase/metabolism , Insulin Resistance , Male , Mice , Mice, Inbred C57BL , Mice, Knockout , Muscle, Skeletal/drug effects , Muscle, Skeletal/metabolism , Phosphoprotein Phosphatases/chemistry , Phosphoprotein Phosphatases/genetics , Protein Subunits
19.
Environ Pollut ; 112(2): 131-43, 2001.
Article in English | MEDLINE | ID: mdl-11234529

ABSTRACT

The use of small-scale experimental units as a means of evaluating the ecological effects of contaminated sediments was examined at the species, family, mixed and phylum levels of taxonomic resolution. Sediments were taken from various locations representing a range of contaminant loads. Containers with these sediments were placed in situ at a relatively uncontaminated location for 90 days. The containers were retrieved and the abundance of the macrofauna which recruited to the containers was estimated. The results showed that the composition of the benthic communities in the more highly contaminated sediments differed significantly from those in less contaminated sediments. Analyses at the different taxonomic levels showed that all but the phylum level data showed some differences in community structure among sediment types. The study showed that small-scale experiments are useful for examining the effects of contaminants and that higher levels of taxonomic resolution can be used to describe variations in the structure of benthic communities at this spatial scale.


Subject(s)
Classification , Environmental Monitoring/methods , Geologic Sediments , Water Pollutants/adverse effects , Animals , Ecosystem , Population Dynamics
20.
Brain Res Mol Brain Res ; 84(1-2): 115-26, 2000 Dec 08.
Article in English | MEDLINE | ID: mdl-11113538

ABSTRACT

In this report, a novel positive-negative epitope tagging approach was developed to study the cellular processing of beta amyloid precursor protein (beta APP). Amino acids centered around the alpha-secretase cleavage site within the A beta sequence were replaced with residues comprising an epitope for which high-affinity monoclonal antibodies are commercially available. The resulting mutant beta APP cDNAs were expressed in human embryonic kidney cells (HEK 293). Cleavage of labeled beta APP by beta- and gamma-secretase(s) results in the release of an epitope-tagged A beta peptide, whereas cleavage by alpha-secretase results in destruction of the epitope. Highly sensitive and specific immunoassays were developed to study processing of this labeled beta APP via the amyloidogenic pathway. Secretion of epitope-tagged A beta was prevented by MDL 28170, a previously described gamma-secretase inhibitor. Confocal microscopic studies revealed that processing and cellular trafficking of epitope-tagged beta APP was not different from wild-type beta APP. These results suggest that positive-negative epitope-tagged beta APP is normally processed within the cell and may be used to identify secretase inhibitors as therapeutics for Alzheimer's disease.


Subject(s)
Amyloid beta-Protein Precursor/metabolism , Endopeptidases/metabolism , Epitopes/metabolism , Protease Inhibitors/pharmacology , Protein Processing, Post-Translational/drug effects , Recombinant Fusion Proteins/metabolism , Alzheimer Disease/drug therapy , Alzheimer Disease/metabolism , Amino Acid Sequence , Amino Acid Substitution , Amyloid Precursor Protein Secretases , Amyloid beta-Protein Precursor/chemistry , Amyloid beta-Protein Precursor/genetics , Amyloid beta-Protein Precursor/immunology , Antibodies, Monoclonal/immunology , Aspartic Acid Endopeptidases , Blotting, Western , Cell Line , Culture Media, Conditioned/chemistry , Culture Media, Conditioned/metabolism , Dipeptides/pharmacology , Enzyme-Linked Immunosorbent Assay , Epitopes/chemistry , Epitopes/genetics , Epitopes/immunology , Humans , Immunohistochemistry , Isoenzymes/antagonists & inhibitors , Isoenzymes/metabolism , Protease Inhibitors/analysis , Protease Inhibitors/therapeutic use , Recombinant Fusion Proteins/chemistry , Recombinant Fusion Proteins/genetics , Recombinant Fusion Proteins/immunology , Sensitivity and Specificity , Transfection
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