1,327 research outputs found
Regulation of insulin-like growth factor-I (IGF-I) and IGF-binding protein-1 (IGFBP-1) mRNA levels in cultured rat hepatocytes
No full textThe liver is a major site of production of circulating levels of insulin-like growth factor-I (IGF-I) and IGF-binding proteins (IGFBPs). We have used primary cultured rat hepatocytes maintained under serum free conditions to explore the regulatory role of various hormones on hepatic IGF-I and IGFBP-1 mRNA levels.IGF-I mRNA levels were stimulated 2.0 to 2.5 fold by bovine growth hormone (bGH) and 1.8 to 2.0 fold by glucagon but on combining bGH and glucagon, a synergistic effect was observed and IGF-I mRNA level was augmented 10 to 12 fold. Octreotide blocked the hGH induced stimulation of IGF-I production in serum and hepatic IGF-I mRNA levels in hypophysectomized rats. This effect could have been partly due to the low levels of glucagon in serum when hypophysectomized rats were treated with hGH and octreotide. Octreotide was also found to inhibit GH stimulated IGF-I mRNA levels in rat hepatocytes.The unique synergy observed with glucagon and bGH on IGF-I mRNA levels in hepatocytes was not reproduced by T, oPRL, dexamethasone, EGF or insulin when each was added in combination with bGH or glucagon. Like glucagon, the addition of IBMX or (Bu)cAMP stimulated IGF-I mRNA levels 1.8 to 2.0 fold, but in the presence of bGH, IGF-I mRNA levels were stimulated 10 to 12 fold. PMA stimulated IGF-I mRNA levels 1.2 to 1.4 fold but displayed no synergism when added with bGH. The stimulatory effect of bGH plus glucagon on IGF-I mRNA levels was inhibited in PKC depleted cells, in the presence of inhibitors of PKC and in the presence of cycloheximide. bGH had no posttranscriptional effect on IGF-I mRNA stability whereas glucagon or (Bu)cAMP stabilized IGF-I mRNA at a posttranscriptional level.In summary, the major hormonal regulators of hepatic IGF-I mRNA levels appear to be GH and glucagon. Hepatic IGF-I mRNA levels are regulated by pathways involving protein kinase C and, protein kinase A as well as by synthesis of one or more protein(s).Glucagon and dexamethasone each stimulated IGFBP-1 mRNA levels 3 to 4 fold whereas bGH and T each inhibited IGFBP-1 mRNA levels 45 to 70%. Insulin, which inhibited IGFBP-1 mRNA levels 95%, was the most powerful inhibitor and was also found to inhibit IGFBP-1 mRNA levels in the presence of dexamethasone. IBMX and (Bu)cAMP stimulated IGFBP-1 mRNA levels 6 to 8 fold whereas PMA inhibited IGFBP-1 mRNA levels 40 to 50%. The inhibitory effect of bGH on IGFBP-1 mRNA levels was abolished in PKC depleted cells and also in the presence of inhibitors of PKC. In the presence of cycloheximide, IGFBP-1 mRNA was superinduced by bGH. bGH had no posttranscriptional effect on IGFBP-1 mRNA whereas glucagon and (Bu)cAMP stabilized IGFBP-1 mRNA at a postranscriptional level.In summary, bGH, T and insulin inhibited whereas dexamethasone and glucagon stimulated IGFBP-1 mRNA levels in hepatocytes. Effect of glucagon may be via elevation of cAMP levels, whereas the effect of bGH may be via activation of PKC levels. The inhibitory effect of bGH appears to require synthesis of one or more protein(s) besides stimulation of PKC levels
Why don't I take the easy way?
No full textPresidential campaign speech by Barry M. Goldwater, Belleville, Illinois
Reforming the Immigration Courts of the United States: Why is There No Will to Make It an Article I Court?
No full textThis article strongly reaffirms the author\u27s support for the use of asylum as a way of providing justice for those fleeing persecution from other countries. Additionally, this article was written to help educate those interested in asylum law by providing some history and background on asylum. Part II of the article briefly discusses the history of asylum; enumerates the eligibility requirements for asylum; describes court proceedings in asylum cases; recounts recent statistics on grants of asylum; and also includes a brief history of our immigration courts. Part III examines the six significant problem areas our immigration courts have wrestled with during the last decade with respect to asylum caseloads. Finally, Part IV examines a few of the proposals put forth over the last thirty years to transform the immigration court system into an Article I Legislative Court
EGF-induced vacuolar (H+)-ATPase assembly: a role in signalling via mTORC1 activation
No full textUsing proteomics and immunofluorescence we demonstrated epidermal growth factor (EGF) induced recruitment of extrinsic V1 subunits of the vacuolar (H+)-ATPase (vATPase) to rat liver endosomes (ENs). This was accompanied by reduced vacuolar pH. Bafilomycin, an inhibitor of vATPase, inhibited EGF-stimulated DNA-synthesis and mammalian target of rapamycin complex 1 (mTORC1) activation as indicated by a decrease in 4E-BP1 phosphorylation, and p70S6K phosphorylation and kinase activity. There was no corresponding inhibition of EGF-induced Akt and Erk activation. Chloroquine, a neutralizer of vacuolar pH, mimicked bafilomycin's effects. Bafilomycin did not inhibit the association of mTORC1 with Raptor nor did it affect AMPK activity. Rather, the intracellular concentrations of essential but not non-essential amino acids, were decreased by bafilomycin in EGF-treated primary rat hepatocytes. Cycloheximide, a translation elongation inhibitor, prevented the effect of bafilomycin on amino acids levels and completely reversed its inhibition of EGF induced mTORC1 activation. In vivo administration of EGF stimulated the recruitment of Rheb but not mTOR to endosomes and lysosomes. This was inhibited by chloroquine treatment. Our results suggest a role for vacuolar acidification in EGF signaling to mTORC1.A l'aide des techniques de Protéomique et d'immunofluorescence, nous avons démontré le recrutement des sous-unités extrinsèques V1 de l'(H+)-ATPase (vATPase) par les endosomes du foie de rat suite à une stimulation à l'EGF (Epidermal Growth Factor). Ce recrutement s'accompagne d'une réduction du pH vacuolaire. L'utilisation de la Bafilomycine, un inhibiteur de la vATPase, inhibe la synthèse d'ADN et de l'activation de mTORC1 (mammalian target of rapamycin complex 1), indiqués par la diminution de la phosphorylation de 4E-BP1, et de la phosphorylation et de l'activité enzymatique de p70S6k. Toutefois, nous n'avons pas observé d'inhibition de l'activation de Akt et de Erk également induites par l'EGF. La Chloroquine, un neutralisateur du pH vacuolaire, imite les effets vus avec la Bafilomycine. Dans des hepatocytes primaires de rat traités avec l'EGF, la Bafilomycine n'inhibe pas l'association de mTORC1 avec Raptor, pas plus qu'elle n'affecte l'activité de AMPK, par contre elle diminue les concentrations intracellulaires des acides aminés essentiels, mais pas des acides aminés non-essentiels. La Cycloheximide, un inhibiteur de l'élongation de la traduction, prévient les effets de la Bafilomycine sur les niveaux d'acides aminés, et renverse complètement son effet inhibiteur sur l'activation de mTOR induite par l'EGF. De plus, l'administration d'EGF in vivo induit le recrutement de Rheb dans les endosomes et les lysosomes, mais pas celui de mTOR, et cette induction est inhibée par l'administration de Chloroquine. Dans l'ensemble, nos résultats suggèrent donc un rôle pour l'acidification vacuolaire dans la signalisation de l'EGF
Characterization of the structure and subcellular distribution of the rat hepatic prolactin receptor
No full textThe structure of rat hepatic prolactin (PRL) receptors was examined in various subcellular fractions by immunoblotting. In all subcellular fractions, a single 42 kDa species was identified. Tri- and/or tetrantennary complex carbohydrates compose 7 kDa of the weight of the receptor. Enzymatic deglycosylation of the mature receptor does not appreciably reduce ligand binding or antibody recognition of the receptor. However, core glycosylation of the receptor is necessary for the acquisition of binding capacity and antibody recognition.The intracellular distribution of PRL receptors was determined by Percoll gradient centrifugation and application of the diaminobenzidine (DAB)-shift methodology. There was a sex-dependent distribution of PRL receptors, with females having a 3-fold higher concentration of receptors in early endosomes than males. This discrepancy disappeared when male rats were treated with estrogen. No such sex-dependent distribution of intracellular receptors were discovered for insulin receptors.Colchicine treatment of estrogen-induced male rats prevented newly synthesized receptors from reaching the cell surface, and allowed the accumulation of at least some of these receptors into an endosomal compartment. These studies suggest that under conditions of colchicine blockade, PRL receptors may access an endosomal compartment by an entirely intracellular route. To date, such a route has only been described for mannose-6-phosphate receptors
Epidermal growth factor-induced DNA synthesis : key roles for phosphatidylinositol 3-kinase and the adaptor protein Gab2
No full textIn primary rat hepatocytes, we found that activation of the Pl3-kinase pathway is both necessary and sufficient to account for EGF-induced DNA synthesis. To identify the mechanism of EGF-induced Pl3-kinase activation, we demonstrated that three distinct p85-associated complexes were formed following EGF: ErbB3-p85, Shc-p85 and a large complex Gab2-Grb2-SHP2-p85. The latter accounted for >80% of total Pl3-kinase activity. Further experiments showed that these complexes are differentially localized in rat liver following EGF treatment. ErbB3-p85 and Shc-p85 complexes were localized to PM and Endosomes; whereas the multimeric Gab2-Grb2-SHP2-p85 complex was formed rapidly and exclusively in cytosol. A central role for Gab2 in EGF-induced Pl3-kinase activation and DNA synthesis was established when we observed that over-expression of wild-type Gab2 augmented these EGF actions, whereas a Gab2 mutant lacking p85 binding sites did not effect such augmentation. Over-expression of the PH-domain of Gab2 did not affect EGF-induced Gab2 phosphorylation, Pl3-kinase activation and DNA synthesis, whereas over-expressed Gab2 lacking the PH-domain was comparable to wild-type Gab2 in respect to these EGF-induced signals. These data demonstrated that Gab2 is phosphorylated and mediates EGF signaling in a PH-domain independent manner. We then explored the mechanism of Gab2 phosphorylation by EGF; our results demonstrated that PP1, a selective inhibitor of Src family kinases, blocked EGF-induced Gab2 tyrosine phosphorylation and downstream events. Moreover, Gab2 phosphorylation was increased in Csk knock-out cells in which Src family kinases are constitutively activated. A constitutive association between Gab2 and Src via proline rich sequences on Gab2 was demonstrated since deletion of proline rich sequences in Gab2 prevented EGF-induced association of Src with Gab2, Gab2 phosphorylation, Pl3-kinase/Akt activation, and DNA synthesis. The role of SHP2 was defi
In vivo effects of peroxoVanadium (PV) compounds as hypoglycaemic agents
No full textVanadium is a trace element found in most living systems. It has various biological properties. In the last 10 years numerous reports showed that Vanadium administered orally could improve the metabolic state of diabetic animals. The combination of vanadate and HO produced the new agents called peroxoVanadium (pV) compounds which exerted more potent insulin mimetic effects by activating the insulin receptor kinase. Their application in the treatment of diabetes could be of great benefit clinically in the future. We demonstrated that long-term oral bpV (phen) (a new pV compound) treatment resulted in a lowering of blood glucose levels, with less toxicity than vanadate in STZ-diabetic rats. bpV(phen) was the first agent other than insulin, that was able to maintain the insulin-deprived diabetic BB rats in good apparent health without ketonuria for 25 days by intraperitoneal injection (IP). Although bpV(phen) was ineffective in reducing glucose levels by IP injection in BB rats, it caused a significant decrease of insulin and C peptide levels and in the insulin dose required to maintain the aglycosuric state of the diabetic BB rats. These observations are consistent with a mechanism of bpV(phen) action at tissue levels. The exploration of the properties of pV compounds may help elucidate both the mechanisms of insulin action and the cause of diabetes, and also may give rise to insulin substitutes which could be orally administered for the treatment of diabetes in the future. However IP injection of bpV (phen) also caused severe toxic side effects. The toxic effects of bpV(phen) included inhibition of food and water intake, acceleration of the onset of diabetes and death. Further studies are required to identify second generation pV compounds with better therapeutic/toxicity ratios and to find ways of delivering pVs orally
In memoriam: Barry MacDonald
No full textBarry MacDonald was the author of Democratic Evaluation (1974) and one of the early founding theorists of the field of program evaluation. I was his colleague and collaborator for 25 years. This short article explains the relationship of evaluation to democracy and the unique intellectual contribution of MacDonald
The construction of Karen Karnak: The multi-author-function
No full textThis thesis is situated within the comparatively recent developments of Web 2.0 and the emergence of interactive WikiMedia, and explores the mode of authorship within a Read/Write culture compared to that of a Read/Only tradition. The hypothesis of this study is that the role of the audience has become merged with the author, and as such, represents new functions and attributes, distinct from a more conventional concept of authorship, in which the roles of audience and author are more separate. Read/Write and participatory culture, as defined by this study, is focused on collaboration, and includes the influences of D.I.Y. culture, Open-Source practices and the production of text by multiple authors. Multi-authorship presents a re-thinking of several concepts which support the notion of the individual author, since the focus of multi-authorship is not on attribution and ownership of a finished text, but on the continued malleability of a text. Modes of multi-authorship, demonstrated in the use of the pseudonyms Alan Smithee and Karen Eliot, represent declarative authors whose names signify multiple origins, whilst concurrently indicating a distinct body of work. The function of these names form an important context to this study, since primary research involves the construction of an experimental mode of multi-authorship utilising WikiMedia technology and the interaction of thirty nine participants, who are invited to create a body of work under the collective pseudonym Karen Karnak. The data generated by this experiment is analysed using aspects of Michel Foucault's author-function to identify and determine power structures inherent in the WikiMedia context. The interplay of power structures, including concepts such as identity, ownership and the body of work, affect the resulting mode of authorship and contribute to the construction of Karen Karnak, suggesting further areas of research into the emerging multi-author
Addict First, Criminal Second – Addiction Fueled Crimes Should be Ineligible for the Three-Strikes Penalty
No full textThe author of this article argues that drug addicts who finance their addiction through crime should be ineligible to receive a prison sentence under a recidivist statute like the three-strikes penalty. Part I introduces the problem, addiction and crime among current prisoners reported by the Department of Justice. Part II discusses Gary Ewing, an addict, a criminal, and a third strike offender. The story of Gary Ewing represents the injustices levied upon an addict/criminal by enhanced sentenced statutes like the three-strikes penalty. Part III is a discussion of the history of repeat offender statutes, primarily focusing on the inception of California’s three-strikes policy and its later modification. Part IV is an analysis of the relationship between the theories of punishment and the three strikes policy and, more importantly, how these models do not fit the addict/criminal. Part V is a discussion of the various constitutional issues that surround the three-strikes penalty. Part VI discusses both the various statutory and the medical community’s definitions of addiction. Part VII explores defenses that are not available to the addict/criminal, but should be. Lastly, Part VIII discusses why breaking the cycle among family generations is so important and the statistics that support this proposition. This section also discusses treatment, the important role it plays in breaking this cycle, why treatment is failing in the country’s penal systems, and the ultimate cost benefit of treatment compared to incarceration
- …
