No abstract

Nine monoclonal antibodies (MoAbs) were produced against Mycobacterium bovis BCG antigen 85 complex. Using isoelectric focusing combined with Western (immunoblot) blot analysis, antigenically related proteins could be identified in culture filtrates from M. tuberculosis, M. bovis, M. Kansasii, M. avium, M. xenopi, M. gordonae, M. fortuitum, M. phlei and M. smegmatis. Most of the MoAbs were found to be broadly cross-reactive between the various mycobacterial species, albeit some minor differences were observed. These MoAbs reacted generally, in each species, with different components. One MoAb (VID1-14) was found to be specifically directed only against antigen 85B from M. bovis, M. tuberculosis and M. kansasii.

The precise molecular mechanisms by which phagocytic cells effect their microbicidal function is unknown. Potential mechanisms that have been identified include low intracellular pH, lysozyme, cationic proteins, lysosomal hydrolases, and oxygen metabolites (1-4). Largely from the study of leukocytes of patients with rare genetic deficiency diseases--which include chronic granulomatous disease (CGD),t gutathione peroxidase, and the reductase deficiencies, glucose-6-phosphate dehydrogenase deficiency and myeloperoxidase deficiency--it has emerged that there exists a close correlation between the respiratory burst in normal phagocytic cells and their cytocidal activity, both of which are impaired in CGD (4-7). It has long been established that one of the early sequelae of the phagocytic event in macrophages is a stimulation of the hexose monophosphate (HMP) shunt, and recent studies indicate that the ability of macrophages to kill parasites intracellularly and possibly tumor cells extracellularly is dependent upon the oxidative burst and production of oxygen radicals including superoxide anion (O2-), hydrogen peroxide (H202), hydroxyl radical, and, possibly, singlet oxygen; 102 (1-4, 8-10). The nature of the cellular enzyme or molecule(s) responsible for the initial reduction of oxygen, the biochemical nature of the electron transferring molecule, and the intracellular localization of the oxidative bactericidal mechanism and the mechanisms of its regulation in the macrophage remain important problems.In previous studies (1 I, 12) we have endeavored to design selective genetic strategies for producing variants in defined functions of cloned macrophage-like cell lines, in the hope that they may yield tractable models for the study of the molecular basis for various macrophage functions. In the present report we describe a cloned, macrophage-like cell line derived from a murine reticulum cell sarcoma that can be stimulated to oxidize glucose via the HMP shunt, and produce 02-and H202, which we believe represents a useful model of activated primary macrophages. A simple strategy was employed to select for variants lacking the ability to reduce nitroblue tetrazolium (NBT), presumably by O2-, which has led to development of a series of clones defective in oxidative metabolism. These macrophage-variant clones lack the * Supported by U. S.

Hexamethylenebisacetamide (HMBA)-induced murine erythroleukemia (MEL) differentiation is a multistep process. Commitment is the capacity to express terminal cell division and characteristics of the differentiated phenotype even after the cells are removed from culture with inducer. Culture of MEL cell line 745A-DS19 (DS19) with HMBA causes commitment to terminal differentiation after a latent period of about 10-12 hr. Previous studies have shown that during this latent period, HMBA causes a number of metabolic changes, including modulation in expression of certain protooncogenes. We now report the development of a MEL cell line (designated V3-17) derived from DS19 that is resistant to vincristine and is (i) markedly more sensitive to HMBA, (ii) induced to commitment without a detectable latent period, and (iN) resistant to the effects of phorbol ester and dexamethasone, which are potent inhibitors of HMBAmediated DS19 differentiation. We suggest that this V3-17 MEL cell line may express a factor that circumvents HMBAmediated early events, which prepare the cells for commitment to terminal differentiation.Hexamethylenebisacetamide (HMBA)-mediated murine erythroleukemia (MEL) cell terminal differentiation is a multistep process (1, 2). Upon culture of MEL cell line 745A-DS19 (DS19) (3) with HMBA (4), there is a latent period of -10 to 12 hr during which commitment to terminal differentiation cannot be detected. Commitment is defined as the capacity to express characteristics of the erythroid differentiated phenotype, including loss of proliferative capacity, despite removal of the inducer (5, 6). This early, latent period is followed by a period during which an increasing proportion of the population expresses characteristics of terminal differentiation, including loss of proliferative capacity.During the latent period, the inducer initiates a number of metabolic changes that precede irreversible commitment to differentiation. Among these are alterations in membrane permeability, which involve Na', K+, and Ca2+ flux (7-9); changes in cell volume (10); a transient increase in cyclic AMP concentration (11); a prompt increase in membraneassociated protein kinase C activity (PKC); the appearance in the cytosol of a Ca2 + -and phospholipid-independent form of PKC, presumably generated by proteolytic cleavage of membrane-bound PKC (12); and the modulation in expression of a number of genes, including c-myb, c-myc, c-fos, and p53 (13)(14)(15)(16). Upon more prolonged culture with HMBA, DS19 cells become irreversibly committed (5, 6). Morphological and molecular changes occur that are similar to normal erythroid terminal cell differentiation, including the coordinated expression of genes for a'-and 83mj-globin, for the heme synthetic enzymes, and for erythroid-specific membrane proteins, as well as suppression of DNA replication and rRNA synthesis (1,17,18).In the present studies we describe the development of a MEL cell line derived from DS19 that is resistant to inhibition of cell growth by vincristine and is de...

Without thromboprophylaxis, knee arthroscopy (KA) carries a low to moderate risk of venous thromboembolism. Over 5 million arthroscopies are performed worldwide yearly. It was our study objective to assess the efficacy and safety of rivaroxaban for thromboprophylaxis after therapeutic KA. Patients undergoing KA in nine Italian teaching or community hospitals were allocated to once-daily rivaroxaban (10 mg) or placebo for seven days in a phase II, multicentre, double-blind, placebo-controlled randomised trial. The primary efficacy outcome was a composite of all-cause death, symptomatic thromboembolism and asymptomatic proximal DVT at three months; major bleeding represented the primary safety outcome. All patients underwent whole-leg ultrasonography at day 7(+1), or earlier if symptomatic. A total of 241 patients were randomised (122 rivaroxaban, 119 placebo), and 234 completed the study. The primary efficacy outcome occurred in 1/120 of the rivaroxaban group and in 7/114 of the placebo group (0.8 % vs 6.1 %, respectively, p=0.03; absolute risk difference, -5.3 %, 95 % CI, -11.4 to -0.8; crude relative risk 0.14, 95 % CI, 0.02 to 0.83; number-needed-to-treat=19). No major bleedings were observed. We found no association between different arthroscopic procedures and thrombotic events. Small sample size, high exclusion rate, and low number of anterior cruciate ligament reconstruction procedures are the main limitations of our study. In conclusion, a seven-day course of 10-mg rivaroxaban may be safely employed for thromboprophylaxis after KA. Whether prophylaxis after KA should be given to all patients, or to selected "high-risk" subjects, remains to be determined. A larger trial to verify our preliminary results is warranted.