Sialyltransferase activity and hepatic tumor growth in a nude mouse model of colorectal cancer metastases.

Sialyltransferase activity (EC 2.4.99.6) was measured in the microsomal fraction of colorectal cancer cell lines using an assay based on the incorporation of [14C]CMP-sialic acid into asialofetuin. In the poorly differentiated lines MIP101 and Clone A, sialyltransferase activity had a Vmax of 0.36 and 0.31 nmol/mg protein/h, respectively, while the moderately differentiated to well-differentiated cell lines HT-29, CCL188, and CX-1 had Vmaxs of 2.46, 1.05, and 1.24 nmol/mg protein/h, respectively. All cell lines tested had a Km of 15.4 (+/- 0.7)(SD) mumol/liter. The better differentiated cells had higher levels of sialyltransferase activity, which correlated with their higher levels of sialic acid and their enhanced ability to form liver metastases in the nude mouse following intrasplenic injection compared to the poorly differentiated cell lines. Treatment of the cell lines with KI-8110, a CMP-sialic acid derivative which prevents incorporation of sialic acid into glycoconjugates, resulted in reduced formation of hepatic metastases by the colorectal carcinoma cell lines in the nude mouse model. It is suggested that reduced sialylation of adhesion molecules such as carcinoembryonic antigen may change the biology of the tumor cell, one consequence of which is the prevention of implantation of the cells into distant sites, resulting in a reduced incidence of metastases.     

The Histocompatibility Complex of Rhesus Monkeys. II. A Major Locus Controlling Reactivity in Mixed Lymphocyte Cultures

Rhesus monkeys have a genetic locus which has a major influence on reactivity in mixed lymphocyte cultures (MLR). This MLR locus is closely linked to the RhL–A system², which controls the serologically defined histocompatibility antigens of this species. Three cases of recombination between RhL–A and the MLR region are described. Consequently, the MLR locus is located outside the RhL–A region proper, possibly adjacent to the locus defining the antigens of the 1st series. The recombination frequency between the MLR and RhL–A regions of rhesus monkeys is similar to that found for the analogous systems of man.
Inhibition of MLR can be achieved by pre-incubation of responder or stimulator cells with cytotoxic anti-RhL–A sera. Such inhibition is highly specific and probably caused by an interaction of the sera with RhL–A surface antigens, not with MLR determinants. Yet, there is circumstantial evidence that non-cytotoxic sera can be produced which inhibit MLR, presumably by affecting MLR determinants on the cell surface.
The relevance of MLR to histocompatibility and the genetic control of the immune response of rhesus monkeys to synthetic antigens, are the subjects of current studies which are briefly discussed.     

Effect of (+)-cyanidanol-3 on receptor activity of lymphocytes and hepatocytes and on hepatocyte-lymphocyte conjugation in alcoholic liver disease

The recirculation of lymphocytes and cell-mediated immunity show profound alterations in alcoholic liver disease. The use of cianidanol corrects a lot of these disturbances, in that: a) it can modify the receptor avidity of hepatocytes, b) it reduces the cell-mediated immune reactivity against liver specific protein antigen, diminishing the auto-immune reactions in alcoholic liver disease, c) it has no effect upon the conjugation process between the hepatocytes as target cells and cytotoxic effector cells, d) it decreases, however, the number of hepatocytes damaged after the conjugation process, and e) as a potent free-radical scavenger, it inhibits the cytotoxic effect of natural killer cells and monocytes, and in the same manner prevents the alteration of the hepatocyte membrane.     

A NEW METHOD FOR DETECTING EYE MOVEMENT IN SLEEP

A new method of detecting eye movements (EMs) during sleep is described. The method consists of an electromechanical measurement using micro-miniaturized silver cup electrodes. These electrodes, when placed on the eyelid, produce electro-oculographic (EOG) recordings similar to the usual electrical method. The eyelid method offers the advantage of a relatively “clean” recording showing only EMs and movement artifact, with no intermingling of EEG and EOG. Furthermore, the method is at least one and one half times as sensitive as the usual EOG technique. In addition to these two special advantages, it also offers the features of conventional methods, convenience of DC coupling, independence from signal converters, ease of analyzing EM directionality, and durability despite the small size of the electrodes. Fabrication of the electrodes, recording configurations, and simultaneous comparisons to both the usual EOG technique and to a strain gauge method are described.     

Effects of racist provocation and social support on cardiovascular reactivity in african american women

It has been speculated that exposure to the chronic stress of racism contributes to the high rates of hypertension among African Americans. Social support may buffer the effects of stress on cardiovascular (CV) health by attenuating stress-induced CV responses that have been linked to hypertension. In this study we investigated the effects of racism and social support on CV reactivity in African American women. Participants showed greater increases in CV and emotional responses while responding and listening to racist provocation. Augmented blood pressure (BP) persisted through recovery following racial stress. Participants receiving no support showed the greatest increases in anger during racist provocation. No significant effects were seen for support on CV reactivity. These results provide some of the first evidence that interactive confrontation with racism elicits significant increases in CV reactivity and emotional distress. Furthermore, individuals receiving less support may be at greater risk for the potentially health-damaging effects of racial stress. These findings may have significant implications for the health of African Americans.     

Characterization of toxins A and B of Clostridium difficile with monoclonal antibodies.

Two monoclonal antibodies (MAbs) were used to learn more about the structures of Clostridium difficile toxins A and B. One of the antibodies, the PCG-4 MAb, reacted specifically with toxin A. This MAb precipitated toxin A and neutralized the enterotoxic but not the cytotoxic activity of the toxin. The site to which the antibody bound was resistant to denaturation with sodium dodecyl sulfate; however, it was destroyed by N-bromosuccinimide. Immunoblot analysis with the PCG-4 MAb revealed the presence of a large number of bands in preparations of denatured toxin A, suggesting that toxin A exists as an aggregate of smaller components. The antibody was covalently coupled to Affi-Gel 10, and the gel was used to purify toxin A from the culture filtrate of a highly toxigenic strain of C. difficile by immunoaffinity chromatography. The second antibody, the G-2 MAb, cross-reacted with toxins A and B. The cross-reaction was confirmed by immunoblot analysis. These results show that toxins A and B share an epitope and suggest that they have a common subunit. The G-2 MAb did not neutralize or precipitate either toxin. The site to which the G-2 MAb bound was partially destroyed by sodium dodecyl sulfate and was resistant to oxidation with N-bromosuccinimide.