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Biomedical subjects

J Ivanoff

Publications and source records attributed to J Ivanoff.

12 recordsLinked to original sources
PubMed2004

Somatostatin is a specific inhibitor of SDF-1alpha-induced T cell infiltration.

The chemokine stromal cell-derived factor 1alpha (SDF-1alpha) is a potent stimulator of T cell infiltration into three-dimensional type I collagen matrices as demonstrated using T cells freshly isolated from blood and an activated T cell clone. The neuropeptide somatostatin selectively inhibits SDF-1alpha induced T cell infiltration by the same T cells including CD4 as well as CD8 positive cells, while somatostatin does not inhibit 'spontaneous' T cell infiltration. A number of other neuropeptides and opioids do not inhibit SDF-1alpha-induced T cell infiltration, indicating that the inhibitory effect is somatostatin-specific. The neuropeptide antagonist cyclosomatostatin abrogated the inhibitory effect of somatostatin on T cell infiltration, indicating that the effect of somatostatin is mediated via specific somatostatin receptors. Somatostatin does not inhibit SDF-1alpha-induced T cell attachment to the collagen substrate, which indicates that this neuropeptide specifically inhibits the process of chemokine-induced T cell penetration and migration through the collagen.

Cells, Cultured↗
PubMed2003

Abnormal expression of chemokine receptors on T-cells from patients with systemic lupus erythematosus.

The expression of chemokine receptors on T-cells and chemokine levels in the blood was studied in 23 patients with SLE (ACR criteria), seven patients with rheumatoid arthritis (RA) and in 15 healthy controls using flow cytometry, RT-PCR and ELISA. The cell surface expression of the chemokine receptors CXCR5 and CCR6 was decreased in SLE patients compared with controls (P = 0.051 and P = 0.002, respectively). The decrease of CXCR5 was confined to SLE patients with inactive disease (SLEDAI < 6) compared with active disease (SLEDAI > 6) and controls. CXCR2 and CCR1 were increased in patients with active SLE compared with patients with inactive disease (P = 0.001 and P = 0.01, respectively) and with controls (P = 0.02 and P = 0.053, respectively). The levels of the chemokines MIP-1alpha MCP-1, SDF-1alpha, IP-10 and RANTES were significantly elevated in SLE patients compared with controls. Patients with renal involvement had increased surface expression of CXCR3 and CCR3 (P = 0.04 in both) and a lower level of soluble IP-10 compared with patients without renal disease (P = 0.025) and compared with controls (P = 0.001). The ratio between CCR5 and CCR3 was significantly increased in RA patients compared with SLE patients and controls supporting a Th1 overweight in RA. In conclusion, patients with SLE showed abnormal T-cell expression of several chemokine receptors and levels of soluble chemokines in their plasma/serum.

Adult↗
PubMed2001

Somatostatin receptor (SSTR) expression and function in normal and leukaemic T-cells. Evidence for selective effects on adhesion to extracellular matrix components via SSTR2 and/or 3.

We have examined normal T-cells and T-cell lines with respect to expression of various somatostatin receptor subtypes (SSTR1--5) using RT-PCR and PCR. To evaluate the function of these receptors we have further studied the effects of subtype specific signalling on T-cell adhesion using somatostatin analogs specific for various receptors as probes. Human T-lymphocytes showed SSTR expression related to activation and stage of differentiation. Normal T-cells (peripheral blood, T-cell clone) and T-leukaemia cell lines expressed SSTR2, SSTR3 and SSTR4. Normal T-cells expressed SSTR1 and SSTR5 while T-leukaemia lines did not. SSTR5 was selectively expressed in activated normal T-cells. T-lymphocytes produced no somatostatin themselves. Somatostatin and somatostatin analogs specific for SSTR2 and/or SSTR3 enhanced adhesion of T-cells to fibronectin (FN), and to a certain extent, also to collagen type IV (CIV) and laminin (LAM). T-lymphocytes express multiple SSTR and somatostatin may therefore regulate lymphocyte functions via distinct receptor subtypes as shown here for adhesion to extracellular matrix components (ECM) via SSTR2 and SSTR3. SSTR expression also distinguishes normal and leukaemic T-cells. Our findings suggest that SSTR subtypes may be useful targets for therapy during inflammatory diseases and malignancies affecting lymphocytes.

Amino Acid Sequence↗
PubMed2001

The presence of a nonresponding effector increases inhibition of return.

Inhibition of return (IOR) refers to the performance disadvantage for targets presented at an exogenously cued location, relative to an uncued location, at relatively long cue-target onset asynchronies. In this experiment, we investigated the influence on IOR of a nonresponding effector (i.e., the index finger of the nonresponding hand) placed on a response key in a simple-RT task. With peripheral cues and targets, IOR and spatial stimulus-response compatibility effects were larger when the nonresponding hand was placed on a response key. IOR--the slowed responding to go signals at the cued location--was accompanied by a lower false alarm rate when no-go signals were presented there. These findings provide direct evidence for a motoric component to IOR wherein some portion of the inhibition is observed as a criterion shift against responding to the cued location.

Adult↗
PubMed2000

A shift of attention may be necessary, but it is not sufficient, for the generation of the Simon effect.

The Simon effect is the performance advantage for spatially corresponding, compared to non-corresponding, target-response ensembles when the location of the target is task irrelevant. In four experiments, we tested the predictions of the attention-shift account of the Simon effect. In all experiments, subject made choice responses with respect to the identity of a central target that followed a spatially non-informative peripheral precue. The first experiment showed a Simon effect away from the precue when the precue was a go/no-go signal: responses to spatially non-corresponding precue-response pairs were faster than responses to spatially corresponding precue-response pairs. The results of the second experiment suggested that this "reverse" Simon effect was not due to inhibition. In the third experiment, a secondary working memory task required the encoding, and later recall, of "oddball" precues. Although the Simon effect was absent, larger Simon effects towards the precue (i.e., responses were faster to spatially corresponding, compared to non-corresponding, precue-response ensembles) were correlated with poorer performance on the memory task. In the last experiment, the identity of completely non-informative precues was congruent, incongruent, or unrelated to the identity of the target. With precues that were unrelated to the identity of the target, there was a Simon effect towards the precues. Conversely, the Simon effect occurred away from the precue when the identity of the precue was related to that of the target. The findings suggest that a shift of attention alone is not sufficient to produce the Simon effect. Rather, the shift of attention must originate from an intentionally defined object. The results are discussed within a framework that integrates the attention-shift and referential-coding hypotheses.

Analysis of Variance↗
PubMed2000

Defective chemokine production in T-leukemia cell lines and its possible functional role.

Peripheral blood lymphocytes and T-cell clones produced nanogram quantities of the chemokines RANTES, MIP-1alpha, MIP-1beta, MCP-1, IL-8 and GRO-alpha as well as the motogenic cytokine HGF. In contrast, various T-leukemia cell lines at different stages of differentiation did not produce the same chemokines/cytokines. In order to study the possible functional importance of the poor chemokine production different T-cell lines were compared with respect to development of motile forms and migration on extracellular matrix components in the absence and presence of various chemokines. RANTES, MIP-1alpha, MIP-1beta, IL-8, GRO-alpha and lymphotactin did not augment the development of motile forms including the size and appearance of the pseudopodia activity of the T-leukemia cell lines. The T-cell lines migrated spontaneously on/to fibronectin in a Boyden chamber assay system. Chemokines augmented the migration of the T-leukemia cell lines on fibronectin in the Boyden system in a chemotactic fashion with peak responses at 10 to 50 ng/ml. Thus, the production of chemokines is defective in neoplastic T-lymphocytes. The defective chemokine production does not seem to play any major role for the basic locomotor capacity of the cells but may modulate the responsiveness to exogenous chemokines.

Cell Movement↗
PubMed1999

Infiltrative capacity of T leukemia cell lines: a distinct functional property coupled to expression of matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of metalloproteinases-1 (TIMP-1).

Infiltrative capacity was found to distinguish separate T leukemia cell lines. Of seven T-cell lines four exhibited capacity to infiltrate Matrigel. Analysis of infiltration was performed at the single-cell level throughout the Matrigel using a depth meter. Further, we examined differences in migration capacity and metalloproteinase production between infiltrating and non-infiltrating T-cell lines. The capacity to infiltrate was not directly correlated to the capacity to adhere to the Matrigel or to migrate on/to extracellular matrix components. It is concluded that infiltration capacity does not simply reflect capacity to migrate but represents a distinct functional property. The production of metalloproteinases and their inhibitors by the separate T-cell lines was analyzed using rt PCR, biosynthetic labelling, zymography, immunoprecipitation and ELISA. All T-cell lines with capacity to infiltrate produced matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of metalloproteinase-1 (TIMP-1) while non-infiltrating cell lines did not express MMP-9. Expression of MMP-1, 2, 3, 10, 14 and 17 showed no correlation to capacity to infiltrate. Analysis of infiltration in the presence of a metalloprotease inhibitor showed an increased number of cells within the gel. This enhancement of infiltration suggests that the function of MMPs and/or their inhibitors in lymphocyte infiltration is more complex than previously thought.

Cell Adhesion↗
PubMed1992

Clinical application of magnetic resonance imaging of the heart and great vessels.

This report reviews the clinical applications of magnetic resonance imaging, (MRI) for the heart and great vessels based on the first 120 patients studied with 1.5 Tesla scanner. Cine scans were obtained in 85% of patients studied with the remainder having T1 spin-echo imaging. MRI provides high-resolution multiplanar images for defining abnormalities in cardiac structure and is especially useful for congenital heart disease. Cine MR evaluates cardiac dynamic functions such as left ventricular volumes and ejection fraction, left ventricular segmental wall motion, and valvular function. It is also useful for detection of aortic and pulmonary arterial disease and diseases of the pericardium. It is concluded that MR has broad applications for diagnosis of cardiac and great-vessel disorders.

Aorta, Thoracic↗
PubMed1986

Psychiatric treatment of erectile dysfunction in urology outpatient clinic.

This study examined the feasibility of establishing a satellite psychiatry service in a urology outpatient clinic for the express purpose of engaging men with inhibited sexual excitement in psychiatric treatment. This approach appeared to be more successful as judged by complete referrals and symptom remission than referral to a psychiatry clinic.

Ambulatory Care↗
PubMed1983

Serum testosterone and prolactin levels in erectile dysfunction.

Serum testosterone and prolactin levels were determined in 52 impotent patients. Fifteen percent were found to have abnormally low testosterone levels. Low testosterone levels were related to clinical ratings of decreased libido and the absence of early morning erections. Suggestive relationships between testosterone levels and scales on the Derogatis Sexual Functioning Inventory were noted.

Adult↗
PubMed1977

A procedure for facilitating physical therapy research.

A procedure for facilitating research by physical therapists in a multidimensional practice setting is presented. The article addresses the need for physical therapists to be aware of research opportunities, and provides them with a means for action when such opportunities occur. The developmental sequence of events is described starting with conceptualization and moving through current utilization of the procedure.

Male↗