MUC1 (CD227) interacts with lck tyrosine kinase in Jurkat lymphoma cells and normal T cells

MUC1 (CD227) is a large transmembrane epithelial mucin glycoprotein, which is aberrantly overexpressed in most adenocarcinomas and is a target for immune therapy for epithelial tumors. Recently, MUC1 has been detected in a variety of hematopoietic cell malignancies including T and B cell lymphomas and myelomas; however, its function in these cells is not clearly defined. Using the Jurkat T cell lymphoma cell line and normal human T cells, we demonstrate that MUC1 is not only expressed in these cells but is also phosphorylated upon T cell receptor (TCR) ligation and associates with the Src-related T cell tyrosine kinase, p56lck. Upon TCR-mediated activation of Jurkat cells, MUC1 is found in the low-density membrane fractions, where linker of T cell activation is contained. Abrogation of MUC1 expression in Jurkat cells by MUC1-specific small interfering RNA resulted in defects in TCR-mediated downstream signaling events associated with T cell activation. These include reduction in Ca2+ influx and extracellular signal-regulated kinase 1/2 phosphorylation, leading to a decrease in CD69 expression, proliferation, and interleukin-2 production. These results suggest a regulatory role of MUC1 in modulating proximal signal transduction events through its interaction with proteins of the activation complex.     

Left Ventricular Mass Estimation by Echocardiography

Echocardiographic determination of left ventricular mass provides prognostic information that is independent of blood pressure. This prognostic information has a graded and continuous relationship with outcome, and is independent of traditional risk factors. This article addresses the prognostic and clinical utility of echocardiography for detection of left ventricular mass. Recommendations will be offered regarding the use of echocardiography for screening in select individuals.     

Emergency surgery for generalized peritonitis caused by cytomegalovirus colitis in a patient with AIDS

Cytomegalovirus infection of the colon is a late and severe complication in human immunodeficiency virus patients. Despite availability of medical treatment, occasional life-saving emergency surgery must be performed. The controversial surgical aspects of treatment are discussed based upon an unusual case of aseptic generalized peritonitis without perforation. The feasibility and value of limited resection are emphasized.     

Development of N-[3-(2',4'-dichlorophenoxy)-2-18F-fluoropropyl]-N-methylpropargylamine (18F-fluoroclorgyline) as a potential PET radiotracer for monoamine oxidase-A

We have synthesized N-[3-(2',4'-dichlorophenoxy)-2-18F-fluoropropyl]-N-methylpropar gylamine (18F-fluoroclorgyline) as a potential positron emission tomography (PET) radiotracer for monoamine oxidase A (MAO-A). The radiosynthesis was carried out by a 18F-fluoride-for-mesylate substitution reaction in approximately 20% radiochemical yield in specific activities of 1-2 Ci/micromol. Selectivity for MAO-A was demonstrated by the high affinity of clorgyline (IC50 = 39 nM) and lower affinity of (R)-deprenyl (IC50 > or = 100 microM) for the inhibition of 18F-fluoroclorgyline binding in vitro in rat brain membranes. The uptake of 18F-fluoroclorgyline in the rat brains was high (> 1.0% injected dose/g). The binding of 18F-fluoroclorgyline in the rat brain correlated with the distribution of MAO-A and was inhibited by preadministration of MAO-A inhibitors, clorgyline, and Ro 41-1049, whereas (R)-deprenyl, a MAO-B blocker, had no inhibitory effect. These results suggest that 18F-fluoroclorgyline is a potential PET radiotracer for MAO-A.     

Enhancement of lipoprotein lipase activity by tissue factor pathway inhibitor

The effect of a basic synthetic peptide, representing the C-terminal region of tissue factor pathway inhibitor (TFPI - Lys254 - Met276), as well as that of the whole protein, on the activity of lipoprotein lipase (LPL) is described. The activity of bovine LPL was measured by chromogenic assay using a water-soluble chromogenic substrate, p-nitrophenyl butyrate. Five and 10 microM concentrations of the peptide increased Vmax of bovine LPL by 48.9% and 85.6% respectively as compared with the buffer control without affecting Km. Poly l-lysine, though positively charged did not have any effect, suggesting the importance of the amino acid sequence of the test peptide. On the other hand, 0.25, 0.5 and 1.0 mM n-butyric acid - a product of LPL catalysis in the chromogenic assay, when added to the incubation mixture decreased Vmax non competitively by 22.8%, 40.4% and 63% respectively as compared with buffer control, confirming the known product inhibition of LPL. A 100-fold molar excess of n-butyric acid produced inhibition of the LPL reaction as compared with the synthetic peptide which produced potentiation, suggesting a 1:100 stoichiometric interaction of the peptide with n-butyric acid. At a fixed concentration of 0.25 mM substrate, 10 nM full length recombinant TFPI, containing the basic C-terminal domain, increased velocity of LPL reaction by 39.4% as compared with buffer control. The same concentration of two-domain recombinant TFPI (TFPI1-160) had no effect. It is possible that negatively charged n-butyric acid is sequestered by the positively charged peptide or the basic region of recombinant full length TFPI. Relieving of product inhibition could then be a possible mechanism of the observed potentiation of bovine LPL activity by the basic peptide or full length recombinant TFPI. The 39.4% increase in reaction velocity of LPL catalysis produced by 10 nM full length recombinant TFPI was comparable to 38.9% increase produced by 5 microM of the basic peptide under the same conditions. A further increase of 78.7% was brought about by 10 microM concentration of the same peptide. The reason for about 500-fold increase in the potency of the whole protein as compared with that of the peptide is not clear. It is possible that in its tertiary conformational state, the whole protein is able to sequester product and relieve product inhibition more effectively than the short linear peptide. Rabbit polyclonal antiserum against the basic peptide partially inhibited LPL activity of human post heparin plasma, measured by radioenzymatic assay using triolein substrate. Since post heparin plasma contains full length TFPI, binding of the added antibody to its basic C-terminus and hence the relative unavailability of latter for product sequestration (oleic acid in this case) could explain the observed inhibition of human LPL activity by antibody against the peptide. Thus by enhancing lipase activity, full length TFPI may facilitate hydrolysis of triglyceride and concomitantly lower factor VII coagulant activity as demonstrated earlier, particularly after heparin injection when both TFPI and LPL are released in circulation.     

Monoamine oxidase A inhibition by fluoxetine: an in vitro and in vivo study

Monoamine oxidase A (MAO-A) inhibition was investigated both in vitro and in vivo in rat brains by using the radioligand, 18F-fluoroclorgyline (N-[3-(2',4'-dichlorophenoxy)-2-18F-fluoropropyl]-N-methylpropa rgylamine). In vitro binding affinities of six compounds, clorgyline, Ro 41-1049, deprenyl, fluoxetine, norfluoxetine and citalopram, were studied. Fluoxetine and norfluoxetine showed in vitro affinities of 36.5 and 68 microM for MAO-A, respectively. Fluoxetine and norfluoxetine also significantly inhibited (more than 20%) the binding of the radioligand in vivo while citalopram and deprenyl showed very poor affinities in vitro for MAO-A and had no effect in vivo. The in vivo effects of the various drugs were directly comparable to their in vitro affinities for binding to MAO-A as seen in the correlation plot of percent control in vivo binding of 18F-fluoroclorgyline and binding affinity, -log IC50 (R2 = 0.979). An acute dose of 20 mg/kg of fluoxetine inhibited binding of 18F-fluoroclorgyline by more than 20%, while lower doses had some significant effects. These results provide evidence on the in vitro and in vivo inhibition of monoamine oxidase A by fluoxetine.     

Complete inversion of the urinary bladder through a vesicovaginal fistula

This is the case of an Indian woman who was hospitalized after a diagnosis of chronic inversion of the uterus with a vesicovaginal fistula. She suffered from urinary incontinence for 40 years, the condition having developed following a difficult labor. Ultimately, she proved to have a complete inversion of the bladder through a vesicovaginal fistula.     

Interpreting the improved outcome of patients with central nervous system metastases managed in clinical trials compared with standard hospital practice*

The aims were to determine the median survival and prognostic factors of patients with central nervous system (CNS) metastases managed with whole‐brain radiation therapy (WBRT), and to explore selection criteria in recently published clinical trials using aggressive interventions in CNS metastases. A retrospective audit was performed on patients managed with WBRT for CNS metastases. Potential prognostic factors were recorded and analysed for their association with survival duration. The proportion of patients with these factors was also compared with those of patients managed under three recently reported studies investigating aggressive interventions, such as radiosurgery and chemotherapy for CNS metastases. Seventy‐three patients were treated with WBRT for cerebral metastases over a 12‐month period. The median survival of the population was 3.4 months (95% confidence interval: 2.7–4.1), with 6‐ and 12‐month survival rates of 30 and 18%, respectively. Significant prognostic factors for prolonged median survival were Eastern Cooperative Oncology Group status 0–2 (P = 0.015), Medical Research Council neurological functional status 0–1 (P = 0.006), and Recursive Partitioning Analysis Class 2 versus Class 3 (P = 0.020). On multivariate analysis, younger patient age (P = 0.02) and better performance status (P < 0.01) were associated with improved outcome. When comparing these characteristics with selected published studies, our study cohort demonstrated a higher proportion of patients with poor performance status, a greater number of metastases per patient and a higher incidence of extracranial disease. This reflects the selected nature of patients in these published studies. Central nervous system metastases confer a poor prognosis and, for the majority of patients, aggressive interventions are unlikely to improve survival. The use of potentially toxic and expensive treatments should be reserved for those few in whom these studies have shown a potential benefit.