P-selectin mediates adhesion of the human melanoma cell line NKI-4: identification of glycoprotein ligands

Activated endothelial cells and stimulated platelets express the cell adhesion molecule P-selectin (CD62P), which mediates adhesion to various leukocytes and certain types of cancer cells. In this study, we show Ca2+-dependent binding of P-selectin to NKI-4 cells, a cell line derived from a human melanoma. The binding is inhibited by P7 (a leukocyte adhesion blocking mAb against P-selectin), but not by PL5 (a leukocyte adhesion blocking mAb against P-selectin glycoprotein ligand-1; PSGL-1). Further, expression of PSGL-1 could not be detected on NKI-4 cells by either PL5 mAb or an Ab against a synthetic peptide corresponding to a portion of the PSGL-1 sequence. P-selectin affinity chromatography of lysates from in vivo [3H]-glucosamine-labeled NKI-4 cells resulted in the isolation of three glycoproteins, with apparent molecular masses of approximately 250, approximately 110, and approximately 100 kDa under reducing conditions and approximately 230, approximately 105, and approximately 85 kDa under nonreducing conditions. These molecules could be precipitated by P-selectin, but not by E-selectin. EDTA and the P7 mAb, but not the PL5 mAb, inhibited the binding of P-selectin to the purified ligands. Surprisingly, we found that sodium chlorate, a sulfation inhibitor, did not inhibit the binding of P-selectin to NKI-4 cells and that [35S]-sulfate did not label the NKI-4 cell ligands. We conclude that P-selectin-dependent adhesion of the human melanoma cell line NKI-4 is mediated by a novel class of glycoprotein ligands.     

The nitric oxide-cGMP pathway may mediate communication between sensory afferents and projection neurons in the antennal lobe of Manduca sexta

The nitric oxide (NO)-cGMP signaling system is thought to play important roles in the function of the olfactory system in both vertebrates and invertebrates. One way of studying the role of NO in the nervous system is to study the distribution and properties of NO synthase (NOS), as well as the soluble guanylyl cyclases (sGCs), which are the best characterized targets of NO. We study NOS and sGC in the relatively simple and well characterized insect olfactory system of the hawkmoth, Manduca sexta. We have cloned Manduca sexta nitric oxide synthase (MsNOS) and two sGCs (MsGCalpha1 and MsGCbeta1), characterized their basic biochemical properties, and studied their expression in the olfactory system. The sequences of the Manduca genes are highly similar to their mammalian homologs and show similar biochemical properties when expressed in COS-7 cells. In particular, we find that MsGC functions as an obligate heterodimer that is stimulated significantly by NO. We also find that MsNOS has a Ca2+-sensitive NO-producing activity similar to that of mammalian neuronal NOS. Northern and in situ hybridization analyses show that MsNOS and the MsGCs are expressed in a complementary pattern, with MsNOS expressed at high levels in the antennae and the MsGCs expressed at high levels in a subset of antennal lobe neurons. The expression patterns of these genes suggest that the NO-sGC signaling system may play a role in mediating communication between olfactory receptor neurons and projection neurons in the glomeruli of the antennal lobe.     

Characterization of arylamine N-acetyltransferase in Enterobacter aerogenes

N-acetyltransferase (NAT) activity was determined by incubation of purified Enterobacter aerogenes enzyme with 2-aminofluorene (2-AF) as the substrate, followed by high pressure liquid chromatography assays. The NAT activity from E. aerogenes was 0.58 +/- 0.08 nmol/min/mg protein for 2-AF. The values of apparent K(m) and Vmax were 0.72 +/- 0.14 mM and 2.45 +/- 0.29 nmol/min/mg protein, respectively, for 2-AF. The optimal pH value for the enzyme activity was 7.5 for the 2-AF tested. The optimal temperature for enzyme activity was 37 degrees C for the 2-AF substrate. The molecular weight of NAT from E. aerogenes was 44.9 kD. Among a series of divalent cations and salts, Zn2+, Ca2+, and Fe2+ were demonstrated to be the most potent protease inhibitors, and only ethylenediaminetetraacetic acid significantly protected the NAT. Iodoacetamide, in contrast to other agents, markedly inhibited NAT.     

The role of anergy in peripheral T cell unresponsiveness

When a T cell's encounter with specific antigen results in good signaling through the T cell antigen receptor yet does not lead to a proliferative response, the T cell enters a state of nonresponsiveness, or anergy. Anergy induction can result from a number of different situations, including antigen presentation by costimulation-deficient or "non-professional" antigen presenting cells, pharmacological blocking of T cell proliferation, or chronic stimulation of the T cell receptor by antigen. Anergy is a long-lived but temporary state characterized by a profound inability of the T cell to produce IL-2. Other effector functions may be affected to variable degrees. Anergy has been characterized most carefully under in vitro conditions, but several experimental models have demonstrated that T cells can also become anergic in vivo. This mechanism for tolerance induction may help to ensure that any mature autoreactive T cells which escape thymic deletion are unable to respond to host tissues. Furthermore, an understanding of the mechanism of anergy induction will most certainly lead to beneficial clinical applications, including improving graft acceptance and avoiding such deleterious immune responses as autoimmunity and allergy.     

A 21-kDa chloroplast heat shock protein assembles into high molecular weight complexes in vivo and in Organelle

The conservation of the carboxyl-terminal "heat shock" domain among small (sm) cytoplasmic and chloroplast heat shock proteins (HSPs) suggests that these smHSPs perform similar functions. Previous studies have established that cytoplasmic smHSPs are found in higher order structures in vivo (approximately 500 kDa). To determine if the chloroplast smHSP is found in similar complexes, we examined the size of the 21-kDa chloroplast smHSP from Pisum sativum, PsHSP21, under non-denaturing conditions. Following sedimentation of chloroplast stromal extracts on sucrose gradients PsHSP21 is detected in fractions corresponding to 10-11 S. Upon non-denaturing gel electrophoresis, PsHSP21 was detected in two high molecular mass complexes of approximately 230 and 200 kDa, in good agreement with the sucrose gradient data. These PsHSP21-containing particles were stable under different salt and Mg2+ conditions, and their integrity was not affected by 1.0% Triton X-100 or 10 mM ATP. To study assembly of the high molecular weight complexes containing PsHSP21, in vitro translated PsHSP21 was imported into chloroplasts and its size was examined. Following import into chloroplasts isolated from heat-stressed plants, greater than 50% of PsHSP21 was recovered in the higher molecular weight forms. In contrast, following import into chloroplasts isolated from control plants the protein was recovered exclusively in a 5 S (approximately 42-kDa) form. These data suggest that preexisting PsHSP21 or other heat-induced factors may be required for assembly of the higher molecular weight particles. We propose that the 10-11 S particles are the functional form of PsHSP21.     

Long latency postural reflexes are under supraspinal dopaminergic control

Scaling of posturally stabilizing long latency (LL) reflexes in tibialis anterior muscles induced by "toe-up" rotational perturbations is abnormal in standing patients with Parkinson's disease. To investigate the contribution of dopaminergic pathways to abnormal scaling, we studied LL reflexes in 22 patients with selective hypodopaminergic syndromes: 10 psychiatric patients taking chronic neuroleptic medication (7 with mild parkinsonism), 8 patients with young-onset Parkinson's disease, and 4 patients with MPTP-induced parkinsonism. Results were compared with those of 10 healthy controls. Stimuli consisted of (a) 10 serial (predictable) perturbations of 4 degrees amplitude, (b) 10 serial (predictable) perturbations of 10 degrees amplitude, and (c) 20 randomly mixed (unpredictable) perturbations of either 4 or 10 degrees amplitude. In normal subjects, LL reflex amplitudes were adapted to match predictable variations in stimulus size, whereas under unpredictable conditions a "default" response emerged that anticipated the 10 degrees perturbation. LL reflex scaling under predictable conditions was intact in patients with neuroleptic-induced parkinsonism and young-onset Parkinson's disease, but the large default LL response under unpredictable conditions was absent. In patients with MPTP-induced parkinsonism, LL reflex scaling was absent during both predictable and unpredictable conditions. We conclude that abnormal scaling of posturally stabilizing LL reflexes is related to decreased supraspinal dopaminergic influence.     

Prognostic factors in resectable gastric cancer: results of EORTC study no. 40813 on FAM adjuvant chemotherapy

BACKGROUND: The high incidence of locoregional recurrences and distant metastases after curative surgery for gastric cancer calls for improved locoregional control and systemic adjuvant treatment. METHODS: In a randomized clinical trial on adjuvant FAM2 chemotherapy, quality of surgery was evaluated by comparing surgical and pathology data. Univariate and multivariate analysis was made to evaluate the effect of prognostic factors on survival and time of recurrence in relation to patients, tumor, and therapy. RESULTS: Of 314 patients randomized from 28 European institutions, 159 comprised the control and 155 the FAM2 group. After a median follow-up of 80 months, no statistically significant difference was found between survivals. However, for recurrence time, treated patients had a significant advantage over controls (p = 0.02). At univariate analysis, statistically significant differences in survival and time to progression emerged for T, N, disease stage and "adequacy" of surgery. The multivariate analysis retained preoperative Hb level, T, N, and "adequacy" of surgery for time of survival; and T, N, "adequacy" of surgery and adjuvant chemotherapy for recurrence time. CONCLUSIONS: Disease stage is the most important prognostic factor. "Adequate" surgery has an important effect. Adjuvant FAM2 delayed time of recurrence, but did not influence overall survival.     

Surgical management of total anomalous pulmonary venous drainage: impact of coexisting cardiac anomalies

BACKGROUND: Recent reports have cited improving results for surgical management of isolated total anomalous pulmonary venous drainage. Complex cases (with other cardiac anomalies) are less frequently reported and are associated with higher mortality. METHODS: Retrospective review identified 170 consecutive patients treated for total anomalous pulmonary venous drainage from 1982 to 1996: 44 cases were "complex" (with significant associated cardiac lesions) and 126 cases were "simple." RESULTS: Operative mortality for simple cases decreased from 26% to 8%, and mortality for complex cases remained constant at 52%. Age, size, and the presence of atrial isomerism were univariate predictors of mortality. Multivariable analysis identified only univentricular hearts and associated cardiac lesions as predictors of operative mortality. Pulmonary artery (n = 16) and arteriopulmonary (n = 7) shunting strategies for complex cases resulted in less than 30% long-term survival. CONCLUSIONS: Despite improvement in survival for simple cases, management of total anomalous pulmonary venous drainage with single-ventricle hearts or other associated cardiac lesions remains problematic.     

Passive but not active CD8+ T cell-based immunotherapy interferes with liver tumor progression in a transgenic mouse model

To evaluate tumor immunotherapies, we used transgenic mice that harbor a progressive liver tumor associated with the expression of the SV40 large tumor T oncoprotein (SV40-T). To induce "self" tumor Ag-specific CD8+ T cells, mice were injected with an immunodominant SV40-T CTL epitope mixed with a heterologous helper peptide. Despite repeated injections, this vaccine failed to raise a tumor-specific CD8+ T cell response that was efficient enough to counteract tumors. Although coimmunization with SV40-T CTL epitope and heterologous helper peptide efficiently recruited the respective Th cells, only low-avidity SV40-T-specific CD8+ T cells were activated. Furthermore, major alterations in SV40-T-specific B and Th cell responses were characterized. In contrast, transfers of higher-avidity CTLs specific for the same SV40-T epitope were effective in counteracting tumors. These results suggest that passive therapies targeted to self tumor Ag may be more suitable than active immunization in the treatment of spontaneous tumors.