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Biomedical subjects

L J Graham

Publications and source records attributed to L J Graham.

11 recordsLinked to original sources
PubMed2001

Bryostatin/ionomycin-activated T cells mediate regression of established tumors.

We have shown that adoptive transfer of tumor-sensitized lymphocytes activated in vitro with bryostatin-1 and ionomycin (B/I), and expanded in culture, can induce regression of small established tumors. We set out to determine whether similar treatment would be effective against larger tumors and what cells mediate this effect. We also attempted to shorten the ex vivo culture period with the ultimate aim of developing a more clinically useful protocol. BALB/c mice were injected in one footpad with IL-2-transfected 4T07 mammary tumor cells. Ten days later, popliteal draining lymph nodes (DLN) were harvested and activated with B/I for 18 h. Mice with either 3-day or 10-day 4T07 flank tumors were treated with cyclophosphamide (100 mg/ kg ip, CYP) alone or CYP followed the next day by infusion of either B/I-activated lymphocytes transferred immediately or activated cells that had been expanded in vitro for 3 or 10 days. In some experiments, mice were also treated with rat anti-mouse CD4 monoclonal antibody (GK1.5) or anti-CD8 antibody (2.43). All mice receiving CYP alone or CYP + sensitized, nonactivated DLN cells demonstrated progressive tumor growth. One hundred percent (6/6) of mice treated with CYP + AIT with B/I-activated,10-day expanded cells had complete regression of 3-day flank tumors. Treatment with activated, nonexpanded cells, induced tumor regression in a majority of mice, but was not as reliable as AIT with expanded cells. We developed a protocol with a shortened expansion period (3-day) that was efficacious for treatment of 4T07 when adoptively transferred to either 3 or 10 day tumor-bearing mice. In vivo depletion of CD4(+) cells had no effect on regression of 3-day tumors, but treatment with anti-CD8 antibody abrogated the effect of immunotherapy. Adoptive transfer of B/I-activated cells, with or without long-term expansion, induced regression of early and late stage 4T07 tumors and is dependent on CD8(+) but not CD4(+) T cells.

Adjuvants, Immunologic↗
PubMed2000

Differential effects of Cbl and 70Z/3 Cbl on T cell receptor-induced phospholipase Cgamma-1 activity.

We demonstrate that the differential effects Cbl and oncogenic 70Z/3 Cbl have on Ca(2+)/Ras-sensitive NF-AT reporters is partially due to their opposing ability to regulate phospholipase Cgamma1 (PLCgamma1) activation as demonstrated by analysis of the activation of an NF-AT reporter construct and PLCgamma1-mediated inositol phospholipid (PI) hydrolysis. Cbl over-expression resulted in reduced T cell receptor-induced PI hydrolysis, in the absence of any effect on PLCgamma1 tyrosine phosphorylation. In contrast, expression of 70Z/3 Cbl led to an increase in basal and OKT3-induced PLCgamma1 phosphorylation and PI hydrolysis. These data indicate that Cbl and 70Z/3 Cbl differentially regulate PLCgamma1 phosphorylation and activation. The implications of these data on the mechanism of Cbl-mediated signaling regulation are discussed.

Calcineurin↗
PubMed2000

Protective role of IL-2 during activation of T cells with bryostatin 1.

Pharmacologic agents such as bryostatin 1 (bryostatin) can regulate cell activation, growth, and differentiation by modulating the activities of protein kinase C isoenzymes. Inhibition of growth of tumor cells and activation of T lymphocytes in vitro are the most recognized consequences of bryostatin treatment. The effect of bryostatin on T cells ranges from induction of apoptotic cell death to T cell activation, expansion, and acquisition of antigen-specific effector functions. Here, we describe the conditions under which these wide ranging effects occur. Mouse mammary tumor 4TO7-IL-2-primed lymph node cells exposed ex vivo to bryostatin upregulated CD25 expression but lost the ability to secrete IL-2. Most of these cells died by apoptosis unless IL-2 was provided for the duration of bryostatin treatment. Analysis of T cell repertoire by screening of T cells for the expression of different Vbeta T cell receptor (TCR) families revealed that bryostatin-induced T cell death was unbiased and Vbeta-nonspecific. Within particular Vbeta clones, only CD25(+) T cells survived exposure to bryostatin and IL-2. Treatment of 4TO7 tumor-bearing mice with a single injection of low dose bryostatin followed by multiple low doses of IL-2, but not with bryostatin alone, delayed tumor growth. These results indicate that activation of T cells with bryostatin should be carried out under protection of exogenous IL-2 to ensure survival and expansion of T cells that may exhibit anti-tumor activity.

Adjuvants, Immunologic↗
PubMed1999

Phenylephrine induces delayed cardioprotection against necrosis without amelioration of stunning.

BACKGROUND: Alpha-adrenergic stimulation induces protection in reperfused ischemic (I/R) myocardium 24 hours later. We tested the hypothesis that phenylephrine improves dysfunction after global I/R by limiting cell death not stunning. METHODS: Rabbits were pretreated with either phenylephrine or vehicle. Twenty-four hours later, isolated hearts underwent either 45 (infarction protocol) or 20 minutes (stunning protocol) of global ischemia before 2 hours of reperfusion (n = 6 per group). Cell death was determined by triphenyl tetrazolium chloride staining (infarction) and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) (apoptosis). RESULTS: Compared with vehicle, phenylephrine pretreatment improved post-I/R-developed pressures in hearts after infarction (53.2 +/- 4.0 vs 35.8 +/- 4.1 mm Hg, p = 0.01) but not stunning protocol (64.3 +/- 8.9 vs 57.7 +/- 6.2 mm Hg, p = NS). The improved developed pressure was due to better diastolic recovery. Systolic pressures were similar between groups. Phenylephrine markedly decreased infarction (9.0 +/- 1.9% vs 40.8 +/- 1.8% for vehicle, p < 0.001) and TUNEL-positive staining. Stunned hearts of either group had less than 3% infarction and no apoptosis. CONCLUSIONS: Phenylephrine pretreatment 24 hours before global I/R improves function by limiting infarction but not stunning.

Animals↗
PubMed1999

Delayed myocardial preconditioning by alpha1-adrenoceptors involves inhibition of apoptosis.

OBJECTIVE: Previous studies have demonstrated that alpha1-adrenoceptor activation increases myocardial resistance to ischemic injury 24 hours later. Here we tested the hypothesis that delayed protection is associated with limited infarction and involves altered expression of pro-apoptotic and/or anti-apoptotic proteins. METHODS: Rabbits were treated with phenylephrine or an equivalent volume of vehicle (n = 6 per group). Twenty-four hours after pretreatment, isolated hearts were perfused with a bovine erythrocyte suspension in modified Krebs solution, subjected to 45 minutes of global ischemia (37 C), and reperfused for 120 minutes. Infarct size was determined by triphenyltetrazolium chloride staining. Apoptosis was quantified by terminal deoxynucleotidyl transferase mediated dUTP nick end labeling. Left ventricular tissue from separate groups of animals (n = 5 per group), 24 hours after pretreatment with phenylephrine or vehicle but without ischemia and reperfusion, was analyzed by Western blotting for content of the anti-apoptotic protein, bclx, and pro-apoptotic protein, bax. RESULTS: Isolated hearts after phenylephrine pretreatment had increased end-reperfusion developed pressures (56.8 +/- 4.9 vs 36.2 +/- 3.9 mm Hg for vehicle, P =.008) and decreased elevated end-diastolic pressures (26.7 +/- 4.5 vs 42.3 +/- 5.0 mm Hg for vehicle, P =.04). Phenylephrine pretreatment abrogated infarction (9.9 +/- 2.4% vs 42.6 +/- 6.3% for vehicle, P =.002) and reduced the number of apoptotic nuclei (24 +/- 4.8 vs 51 +/- 4.6 for vehicle, P = .038). Analysis by Western blotting showed that the ratio of bclx to bax protein increased in phenylephrine-pretreated hearts (2.65 +/- 0.5 vs 1.0 +/- 0.1 for vehicle, P =.008). CONCLUSION: Delayed myocardial protection to infarction mediated by alpha1-adrenoceptor activation involves an increased bclx/bax ratio, thereby limiting apoptotic cell death.

Adrenergic alpha-Agonists↗
PubMed1999

Acute brain death alters left ventricular myocardial gene expression.

OBJECTIVES: The depressed myocardial function observed in brain dead organ donors has been attributed to massive sympathetic discharge and catecholamine cardiotoxicity. Because elevated catecholamines are associated with altered myocardial gene expression, we investigated whether acute brain death from increased intracranial pressure alters the expression of myocardial gene products important in contractility. METHODS: A balloon expansion model was used to increase intracranial pressure in rabbits (n = 22). At timed intervals after brain death, mean arterial pressure, heart rate, electrocardiograms, histologic myocardial injury, and systemic catecholamines were assessed. Messenger RNA levels encoding myofilaments, adrenergic receptors, sarcoplasmic reticulum proteins, transcription factors, and stress-induced programs were measured with blot hybridization of total left ventricular RNA. RESULTS: Increased intracranial pressure induced an immediate pressor response that temporally coincided with diffuse electrocardiographic ST segment changes. Systemic epinephrine and norepinephrine levels concurrently increased (5- to 8-fold within 1 minute), then fell below baseline within 2 hours, and remained depressed at 4 hours. By 1 hour, histologic injury was evident. Four hours after the induction of increased intracranial pressure, levels of messenger RNA-encoding skeletal and cardiac alpha-actins, egr-1, and heat shock protein 70 were significantly increased. Sham-operated animals did not exhibit these changes. CONCLUSIONS: Select changes in myocardial gene expression occur in response to increased intracranial pressure and implicate ventricular remodeling in the myocardial dysfunction associated with acute brain death.

Actin Cytoskeleton↗
PubMed1999

Functional independence and interdependence of the Src homology domains of phospholipase C-gamma1 in B-cell receptor signal transduction.

B-cell receptor (BCR)-induced activation of phospholipase C-gamma1 (PLCgamma1) and PLCgamma2 is crucial for B-cell function. While several signaling molecules have been implicated in PLCgamma activation, the mechanism coupling PLCgamma to the BCR remains undefined. The role of PLCgamma1 SH2 and SH3 domains at different steps of BCR-induced PLCgamma1 activation was examined by reconstitution in a PLCgamma-negative B-cell line. PLCgamma1 membrane translocation required a functional SH2 N-terminal [SH2(N)] domain, was decreased by mutation of the SH3 domain, but was unaffected by mutation of the SH2(C) domain. Tyrosine phosphorylation did not require the SH2(C) or SH3 domains but depended exclusively on a functional SH2(N) domain, which mediated the association of PLCgamma1 with the adapter protein, BLNK. Forcing PLCgamma1 to the membrane via a myristoylation signal did not bypass the SH2(N) domain requirement for phosphorylation, indicating that the phosphorylation mediated by this domain is not due to membrane anchoring alone. Mutation of the SH2(N) or the SH2(C) domain abrogated BCR-stimulated phosphoinositide hydrolysis and signaling events, while mutation of the SH3 domain partially decreased signaling. PLCgamma1 SH domains, therefore, have interrelated but distinct roles in BCR-induced PLCgamma1 activation.

Adaptor Proteins, Signal Transducing↗
PubMed1998

Sequences surrounding the Src-homology 3 domain of phospholipase Cgamma-1 increase the domain's association with Cbl.

SH3 domains are protein modules that interact with proline-rich polypeptide fragments. Cbl is an adapter-like protein known to interact with several SH3 domains, including the PLCgamma1 SH3 domain and the Grb2 amino terminal SH3 domain. Here we explore whether sequences surrounding the PLCgamma1 SH3 domain core sequence (aa.796-851) can affect the binding to Cbl, a target used as a prototypical ligand. Consistent with previous reports, our results demonstrated a weak binding of Cbl to GST fusion proteins that strictly encompass the structural core of the PLCgamma1 SH3 domain but a high-avidity binding to the Grb2 amino-terminal SH3 domain. Inclusion of amino acids immediately flanking the PLCgamma1 SH3 core domain, however, substantially increased binding of Cbl to a level comparable to that of the Grb2 amino-terminal SH3 domain. The interaction of this extended PLCgamma1 SH3 domain fusion protein with Cbl was shown to depend entirely upon the interaction of the domain with a proline-rich motif in Cbl, ruling out the possibility that amino acids adjacent to the core SH3 domain of PLCgamma1 provide independent Cbl binding. These data suggest that sequences surrounding the SH3 domain of PLCgamma1 may contribute to or stabilize the association of the domain with the target protein, thus increasing its binding efficiency.

Binding Sites↗
PubMed1997

Cbl-mediated regulation of T cell receptor-induced AP1 activation. Implications for activation via the Ras signaling pathway.

The functional role of Cbl in regulating T cell receptor (TCR)-mediated signal transduction pathways is unknown. This study uses Cbl overexpression in conjunction with a Ras-sensitive AP1 reporter construct to examine its role in regulating TCR-mediated activation of the Ras pathway. Cbl overexpression in Jurkat T cells inhibited AP1 activity after TCR ligation. However, AP1 induction by 4beta-phorbol 12-myristate 13-acetate, which up-regulates Ras activity in a protein kinase C-dependent, TCR/tyrosine kinase-independent manner, was not affected by Cbl overexpression. Cbl overexpression also did not affect AP1 induction by an activated Ras protein or a membrane-bound form of the guanine nucleotide exchange factor Sos. In addition, activation of the mitogen-activated protein kinase Erk2 was decreased by Cbl overexpression. Therefore, Cbl regulates events that are required for full TCR-mediated Ras activation, and data are presented to support a model whereby Cbl regulates events required for Ras activation via its association with Grb2.

Adaptor Proteins, Signal Transducing↗
PubMed1995

Practice based health needs assessment: use of four methods in a small neighbourhood.

OBJECTIVE: To explore the use of four methods to define health needs in a community, with a view to formulating guidelines for practice based assessment of health needs. DESIGN: Collection of data on health needs for a specific neighbourhood with four complementary methods: rapid participatory appraisal, postal survey, analysis of routinely available small area statistics, and collation of practice held information. SETTING: Council estate of 670 homes in Edinburgh. MAIN OUTCOME MEASURES: Description and comparison of health needs found by the different methods. RESULTS: Each method yielded particular insights into both health and health care needs. CONCLUSIONS: An extended primary care team with public health support can assess health and health care needs in a neighbourhood by means of a mixture of quantitative and qualitative methods. Different methods may be more suitable to assess different health needs or to explore potential service provision in the community or in primary or secondary care. A composite method may be most informative.

Chronic Disease↗