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T Harding

Publications and source records attributed to T Harding.

At least 19 recordsLinked to original sources
PubMed2001

Gene transfer of the JNK interacting protein-1 protects dopaminergic neurons in the MPTP model of Parkinson's disease.

Increasing evidence suggests that apoptosis may be the underlying cell death mechanism in the selective loss of dopaminergic neurons in Parkinson's disease. Because the inhibition of caspases provides only partial protection in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine/1-methyl-4-phenylpyridinium (MPTP/MPP(+)) model of Parkinson's disease, we investigated the role of the proapoptotic c-Jun N-terminal kinase (JNK) signaling cascade in SH-SY5Y human neuroblastoma cells in vitro and in mice in vivo. MPTP/MPP(+) led to the sequential phosphorylation and activation of JNK kinase (MKK4), JNK, and c-Jun, the activation of caspases, and apoptosis. In mice, adenoviral gene transfer of the JNK binding domain of JNK-interacting protein-1 (a scaffold protein and inhibitor of JNK) inhibited this cascade downstream of MKK4 phosphorylation, blocked JNK, c-Jun, and caspase activation, the death of dopaminergic neurons, and the loss of catecholamines in the striatum. Furthermore, the gene transfer resulted in behavioral benefit. Therefore, inhibition of the JNK pathway offers a new treatment strategy for Parkinson's disease that blocks the death signaling pathway upstream of the execution of apoptosis in dopaminergic neurons, providing a therapeutic advantage over the direct inhibition of caspases.

Adaptor Proteins, Signal Transducing↗
PubMed2001

Differential internalization of mammalian and non-mammalian gonadotropin-releasing hormone receptors. Uncoupling of dynamin-dependent internalization from mitogen-activated protein kinase signaling.

Desensitization and internalization of G-protein-coupled receptors can reflect receptor phosphorylation-dependent binding of beta-arrestin, which prevents G-protein activation and targets receptors for internalization via clathrin-coated vesicles. These can be pinched off by a dynamin collar, and proteins controlling receptor internalization can also mediate mitogen-activated protein kinase signaling. Gonadotropin-releasing hormone (GnRH) stimulates internalization of its receptors via clathrin-coated vesicles. Mammalian GnRH receptors (GnRH-Rs) are unique in that they lack C-terminal tails and do not rapidly desensitize, whereas non-mammalian GnRH-R have C-terminal tails and, where investigated, do rapidly desensitize and internalize. Using recombinant adenovirus expressing human and Xenopus GnRH-Rs we have explored the relationship between receptor internalization and mitogen-activated protein kinase signaling in HeLa cells with regulated tetracycline-controlled expression of wild-type or a dominant negative mutant (K44A) of dynamin. These receptors were phospholipase C-coupled and had appropriate ligand affinity and specificity. K44A dynamin expression did not alter human GnRH-R internalization but dramatically reduced internalization of Xenopus GnRH-R (and epidermal growth factor (EGF) receptor). Blockade of clathrin-mediated internalization (sucrose) abolished internalization of all three receptors. Both GnRH-Rs also mediated phosphorylation of ERK 2 and for both receptors, this was inhibited by K44A dynamin. The same was true for EGF- and protein kinase C-mediated ERK 2 phosphorylation. ERK 2 phosphorylation was also inhibited by a protein kinase C inhibitor but not affected by an EGF receptor tyrosine kinase inhibitor. We conclude that a) desensitizing and non-desensitizing GnRH-Rs are targeted for clathrin-coated vesicle-mediated internalization by functionally distinct mechanisms, b) GnRH-R signaling to ERK 2 is dynamin-dependent and c) this does not reflect a dependence on dynamin-dependent GnRH-R internalization.

Animals↗
PubMed2000

Desensitization and internalization of human and xenopus gonadotropin-releasing hormone receptors expressed in alphaT4 pituitary cells using recombinant adenovirus.

Nonmammalian vertebrates express at least two forms of GnRH and distinct forms of GnRH receptor (GnRH-R) have coevolved with their ligands. Mammalian and nonmammalian GnRH-R have key structural differences (notably the lack of C-terminal tails in mammalian GnRH-R) and comparative studies are beginning to reveal their functional relevance. However, cellular context and receptor density influence G protein-coupled receptor function and may be important variables in such work using heterologous expression systems. Here we report a comparative study using alphaT4 cells (gonadotrope progenitors that lack endogenous GnRH-R) transfected with a mammalian (human) or nonmammalian (Xenopus laevis type I) GnRH-R. Because conventional transfection strategies proved inefficient, recombinant adenovirus expressing these receptors were constructed, enabling controlled and efficient GnRH-R expression. When expressed in alphaT4 cells at physiological density, these GnRH-Rs retain the pharmacology of their endogenous counterparts (as judged by ligand specificity in radioligand binding and inositol phosphate accumulation assays) but do not activate adenylyl cyclase and are not constitutively active. Moreover, the Xenopus GnRH-R rapidly desensitizes and internalizes in these cells, whereas the human GnRH-R does not, and the internalization rates are not dependent upon receptor number. These data extend studies in COS, HEK, and GH3 cells showing that other GnRH-R with C-terminal tails desensitize and internalize rapidly, whereas tail-less mammalian GnRH-R do not. Retention of these distinctions at physiological receptor density in gonadotrope lineage cells, supports the argument that the evolution of nondesensitizing mammalian GnRH-Rs is functionally relevant and related to the development of mammalian reproductive strategies.

Adenoviridae↗
PubMed1999

Human rights aspects of transsexualism.

The problem of changing the civil status of transsexuals has been tackled in different ways in various European countries. Six applications made by transsexuals have led to judgments by the European Court of Human Rights. These cases illuminate some specific aspects of the relationships between health, law, and human rights, including criteria used to determine gender and the impact of authorities' refusal to modify civil status, which may be seen as violating the right to be free from inhuman or degrading treatment; respect for the private and family life of transsexuals; and the right to marry. Only one Court decision found a State party (France) to be in violation of the ECHR for refusing a transsexual the right to change civil status. This judgment, however, has left open a number of outstanding issues.

Europe↗
PubMed1998

Regulation of a calcium-dependent tyrosine kinase in vascular smooth muscle cells by angiotensin II and platelet-derived growth factor. Dependence on calcium and the actin cytoskeleton.

A novel, p125FAK homologue, CADTK, has been detected in neural, epithelial, or hematopoietic cells but not in fibroblasts. We now demonstrate CADTK expression in a mesenchymal cell, rat aortic smooth muscle cells (RSMC). Angiotensin II (Ang II) or platelet-derived growth factor (PDGF-BB and PDGF-AA) markedly stimulated CADTK tyrosine phosphorylation in RSMC but did not affect p125FAK phosphorylation. The PDGF-depedent CADTK tyrosine phosphorylation was slower and more prolonged than that of Ang II, correlating well with the differential effects of these agonists on cytosolic calcium ([Ca2+]i) signaling. An intracellular calcium chelator inhibited both the rapid and sustained activation of CADTK by Ang II and PDGF. Extracellular calcium chelation inhibited the PDGF-stimulated increase in CADTK tyrosine phosphorylation as well as the sustained (but not the early) activation by Ang II. In contrast, p125FAK tyrosine phosphorylation was maximal in quiescent, adherent RSMC and was not affected by incubation with EGTA. Depletion of protein kinase C activity partially inhibited both the Ang II- and PDGF-induced CADTK tyrosine phosphorylation. Additional results confirm a relation between CADTK and the cytoskeleton. First, the tyrosine phosphorylation of paxilin correlated with activation of CADTK; this increase was inhibited by EGTA. Second, cytochalasin D blocked the PDGF- or Ang II-stimulated tyrosine phosphorylation of CADTK, suggesting a role for the cytoskeleton in agonist-dependent CADTK activation. Third, immunofluorescence analysis of CADTK localization demonstrated actin-like cytoskeleton staining extending into focal contacts. These results suggest that in mesenchymal cells, CADTK is localized to and activated by an actin cytoskeleton-dependent mechanism; a mechanism that is regulated in a calcium and protein kinase C-dependent manner independently of p125FAK.

Angiotensin II↗
PubMed1997

Applications in in ovo technology.

By mid-August 1995, 55% of broiler embryos in North America were vaccinated for Marek's disease using the INOVOJECT system, with 201 INOVOJECT machines placed with 16 of the top 25 poultry producers, providing the industry with the capacity to inject in excess of 400 million eggs per month or about 5 billion eggs per annum. In ovo administration of a bursal disease antibody-infectious bursal disease virus (BDA-IBDV) complexed vaccine to specific-pathogen-free (SPF) embryos was safer and more potent than conventional IBDV vaccine alone because it delayed the appearance of bursal lesions, produced no early mortality, produced higher geometric mean antibody titers against IBDV, and generated protective immunity against challenge. In ovo administration of a BDA-IBDV complexed vaccine to broiler embryos generated antibody titers against IBDV sooner than conventional virus vaccinates, and generated protective immunity against challenge Direct DNA injection of plasmid DNA encoding beta-galactosidase into breast muscle in ovo and posthatch was an effective means to achieve both gene transfer and expression, with potential for the development of gene vaccines using plasmids encoding protective antigens from poultry pathogens. In ovo administration of 800 U chicken myelomonocytic growth factor (cMGF), a chicken hematopoietic cytokine for cells of the monocytic-granulocytic lineages, significantly reduced mortality associated with Escherichia coli exposure within the hatcher when compared to PBS controls (6.1 vs 12.4, P < or = 0.05), but not when compared to a yeast expression control. A procedure was developed enabling injection prior to the onset of incubation without compromising embryo viability. This in ovo injection process has opened up the window of embryo development during incubation for intervention, as illustrated by the 100% male phenotype produced in chicks hatching from eggs injected with aromatase inhibitor prior to incubation. These data illustrate some of the in ovo applications presently in use by the poultry industry, and under development or in research at EMBREX.

Animals↗
PubMed1996

[Information on health risks in prisons: evaluation of a leaflet].

An illustrated full colour brochure has been elaborated for Swiss prisoners. This brochure, named "Hygiene and Health in detention", concerns transmissible diseases in general and AIDS in particular. It is meant to replace typed A4 sheets which were not generally read. The evaluation of the brochure took place in a Swiss prison on the basis of 22 questions put to inmates during interviews. Answers of inmates having received the old sheet were compared with answers of inmates who received the new brochure. The evaluation concerning the informations' presentation is positive. The brochure is more attractive than the A4 sheet thanks to its illustrated and coloured presentation (chi-square = 6.52, p = 0.01). Prisoners remember having received the brochure more than the old sheet (chi-square = 10.02, p = 0.001). More prisoners have read the folder than the A4 sheet (chi-square = 4.22, p = 0.04). The evaluation concerning the principal preventive messages is only partially positive. Inmates do not appear to have assimilated the medical information any better than from the old A4 sheet.

Adult↗
PubMed1996

Disruption of the yeast ATH1 gene confers better survival after dehydration, freezing, and ethanol shock: potential commercial applications.

The accumulation of trehalose is a critical determinant of stress resistance in the yeast Saccharomyces cerevisiae. We have constructed a yeast strain in which the activity of the trehalose-hydrolyzing enzyme, acid trehalase (ATH), has been abolished. Loss of ATH activity was accomplished by disrupting the ATH1 gene, which is essential for ATH activity. The delta ath1 strain accumulated greater levels of cellular trehalose and grew to a higher cell density than the isogenic wild-type strain. In addition, the elevated levels of trehalose in the delta ath1 strain correlated with increased tolerance to dehydration, freezing, and toxic levels of ethanol. The improved resistance to stress conditions exhibited by the delta ath1 strain may make this strain useful in commercial applications, including baking and brewing.

Arabidopsis Proteins↗
PubMed1994

J-P Allain.

Explore the source record for details and available documents.

Blood Transfusion↗
PubMed1991

Treatment of opiate withdrawal on entry to prison.

Forty-nine opiate-dependent persons entering remand prison were treated with methadone over 5-10 days in decreasing doses according to standard practice of the prison medical service. The prisoners were mainly young, unmarried men with an average of 5 years regular opiate use and an average of four previous imprisonments; 45% were known to be HIV infected, although routine testing was not carried out. Ten were on methadone maintenance prior to imprisonment. Urine analysis on entry detected an average of three psychoactive substances, principally opiates, benzodiazepines and cannabis. Prescribed starting doses of methadone were not correlated to independently assessed withdrawal severity. Starting doses were related to prisoners' requests and to their age. Withdrawal severity decreased after 4 days treatment but symptom relief was incomplete. Treating withdrawal symptoms on entry to prison poses unsolved ethical and practical problems.

Adult↗