One-step competitive immunochromatographic assay for semiquantitative determination of lipoprotein(a) in plasma

Numerous studies have associated high concentrations of lipoprotein(a) [Lp(a)] with atherosclerosis. We developed a rapid, one-step competitive immunochromatographic assay to measure Lp(a) in plasma. The assay is performed on a nitrocellulose membrane strip and the result is determined by a visual readout of rust-colored colloidal selenium. The assay is based on the principle that Lp(a) in the sample will compete with Lp(a)-coated colloidal selenium for binding to the anti-Lp(a) monoclonal antibody immobilized on the assay strip in the format of four ladder bars. The number of capture bars that appear as a result of the formation of colloidal selenium color is proportional to the concentration of the Lp(a) protein in the samples. The strip assay semiquantitatively measures Lp(a) concentrations ranging from 0 to 180 mg/L of Lp(a) protein in serum, plasma, or fingerstick whole-blood samples. This assay appears very useful for quick identification of individuals with above-normal concentrations of plasma Lp(a) protein (> 70 mg/L), and has potential for monitoring a patient's response to treatment with Lp(a)-lowering drugs.

A subset of anti-CD21 antibodies promote the rescue of germinal center B cells from apoptosis

Germinal center cells (GCC) are programmed to die by apoptosis unless they receive a positive signal for rescue. The primary signal in vivo is believed to be dependent on interaction with antigen held as immune complexes on follicular dendritic cells (FDC), a subset of which express large amounts of CD23, a low-affinity receptor for IgE. Recombinant soluble CD23 (sCD23) and interleukin-1 have been found to potentiate the survival of GCC in vitro. Recently, CD23 was shown to interact specifically with a ligand other than IgE, namely CD21 (CR2/Epstein-Barr virus receptor). In the present study, we show that a subset of anti-CD21 monoclonal antibodies behave similarly to soluble CD23 in their effect on GCC inasmuch as they: (i) diminish the occurrence of apoptosis; (ii) promote a plasmacytoid appearance in rescued cells; (iii) up-regulate expression of the Bcl-2 proto-oncogene. These findings indicate that FDC-derived CD23 exerts its effects on GCC via CD21.

Beta 2-adrenoceptor stimulation augments the IL-4-induced CD23 expression and release and the expression of differentiation markers (CD14, CD18) by the human monocytic cell line, U 937

The effect of beta 2-adrenoceptor agonists and interleukin-4 (IL-4) on the CD23 expression on, and release from, the human promonocytic cell line, U 937, was investigated. As assessed by flow cytometry, incubation of U 937 cells in the presence of salbutamol, fenoterol or IL-4 induced a concentration- and time-dependent increase in CD23 expression, that was maximal after 48 hr and followed by a decrease thereafter. In addition, salbutamol potentiated the effect of IL-4, the optimal concentration of the drug being a function of the concentration of this cytokine. This synergy between IL-4 and beta 2-adrenoceptor agonists was also observed for the release of the soluble form of CD23. The effect on CD23 expression of salbutamol and fenoterol, but not of IL-4, was blocked in the presence of D,L-propranolol (1 microM) or butoxamine (1 microM). The alpha-adrenoceptor agonist, norepinephrine (1 microM), was ineffective in inducing CD23 expression or potentiating the one evoked by IL-4. Salbutamol down-regulated the expression of Fc gamma RI (CD64) and Fc gamma RII (CD32) whereas IL-4 was ineffective. Only when added together at the onset of the culture did salbutamol and IL-4 induce, after 48 hr, the expression of the monocyte marker, CD14. The expression of CD18 was up-regulated in response to salbutamol either alone or in combination with IL-4, this cytokine alone being inefficient. These data suggest that IL-4 and beta 2-adrenoceptor agonists induce differentiation of U 937 cells into monocyte-like cells.

Stimulation of tyrosine phosphorylation without inositol lipid hydrolysis in human B lymphocytes on engaging CD72

Occupancy of CD72 on resting tonsillar B cells by monoclonal antibodies (mAb) promotes entry into the G1 phase of the cell cycle with an accompanying increase in MHC Class II expression and provides a co-stimulus to immobilized anti-mu for driving DNA synthesis. We now report that engagement of CD72 by mAb stimulates tyrosine phosphorylation in B cells with a peak of activity seen at 5-10 min. Two major substrates of 29 and 57 kDa showed a basal level of phosphorylation which increased with time, while a 40 kDa protein and several other minor components were phosphorylated de novo on the addition of mAb to CD72. Inositol lipid hydrolysis was found to be unperturbed, although a shallow rise in the basal level of intracellular free Ca2+ was provoked on engaging CD72. Receptor cross-linking was not a requirement for signaling human B cells through CD72: simple occupancy by univalent antibody was sufficient both to trigger the rise in basal [Ca2+]i and to promote DNA synthesis.

Which motoric condition is most effective for teaching spelling to students with and without learning disabilities?

The purpose of this study was to determine the efficacy of three motoric conditions (writing, tracing, and computer keyboarding) on the spelling performance of 24 third- and fourth-grade students without learning disabilities (NLD) (15 males, 9 females) and 24 third- and fourth-grade students with learning disabilities (LD) (16 males, 8 females). This study applied empirically based procedures for teaching spelling, examined student performance over time, and incorporated student interviews concerning their preference for motoric condition. For number of words spelled and proportion of bi-grams (correct letter sequences) used correctly, significant differences were found between the LD and NLD groups, both at posttest and follow-up, with the NLD students learning to spell more words and apply more correct bi-grams than the students with LD. There was no significant effect for condition for either words spelled or bi-grams, indicating that students did not learn significantly more words in the writing, tracing, or computer condition. There was also a significant time effect indicating that the accuracy of both groups decreased over time from posttest to follow-up for both words and bi-grams. Interviews revealed that students in both groups preferred the computer condition; however, they believed that they learned best in the writing and tracing conditions.

Functional interaction between beta 2-adrenoceptor agonists and interleukin-4 in the regulation of CD23 expression and release and IgE production in human

Normal human peripheral blood mononuclear cells (PBMC) produced IgE when stimulated with IL-4. In the present report it was shown that beta 2-adrenoceptor agonists, salbutamol and fenoterol, potentiated the IL-4-induced IgE production without significantly affecting the expression of the low affinity receptor for IgE at the cell surface of monocytes and B lymphocytes. However, beta 2-adrenoceptor agonists were shown to enhance at day 7 the IL-4-induced release of the soluble form of CD23 (sCD23) by PBMC. This effect was specific since a beta-adrenoceptor antagonist, D,L-propranolol, inhibited the IL-4-induced IgE production by these cells. Alternatively, the beta 2-adrenoceptor agonists inhibited the production by these cells of interferon-gamma (IFN-gamma) but did not affect the production of IL-4 when stimulated with phytohemagglutinin A + a phorbol ester. These data suggest that beta 2-adrenoceptor agonists influence the IL-4-induced IgE production in humans by enhancing the release of sCD23 and inhibiting the production of endogenous IFN-gamma. In addition to the effect on the IL-4-induced IgE production it was shown that beta 2-adrenoceptor agonists potentiated the effect of IL-4 on a human promonocytic cell line, U 937, by enhancing CD23 expression and release and by inducing the differentiation of these cells into monocyte-like cells. Taken together, these data indicate that beta 2-adrenoceptor agonists potentiated the effect of IL-4 and that this functional interaction is different considering the cell-lineage and the stage of differentiation of these cells.

Polymorphonuclear cell-mediated vascular injury in anergic surgical patients

We examined the responses of primed polymorphonuclear neutrophils (PMNs) adhered to vascular endothelium, which can lead to endothelial cell damage as a mechanism of the capillary leak syndrome, the main cause of death in anergic patients. We tested PMNs from (1) preoperative reactive patients, (2) preoperative anergic patients, (3) anergic patients in the surgical intensive care unit, and (4) healthy controls for in vitro adherence and cytotoxicity on cultured human vein endothelial cells. Adherence of PMNs was 12.9% +/- 3.9% in preoperative anergic patients and 13.1% +/- 3.2% in anergic patients in the surgical intensive care unit compared with 9.0% +/- 2.1% in preoperative reactive patients (P < .05). Cytotoxicity was 6.0% +/- 2.8% in preoperative reactive patients, 13.7% +/- 4.1% in preoperative anergic patients, and 14.3% +/- 4.6% in anergic patients in the surgical intensive care unit. The PMNs from preoperative anergic patients were more cytotoxic against human vein endothelial cells when stimulated by Staphylococcus epidermidis or formyl-methionyleucylphenylalanine. We conclude that PMNs from anergic surgical patients adhere more to endothelial cells and can produce increased cytotoxicity that may lead to detrimental results.

Second-messenger pathways involved in the regulation of survival in germinal-centre B cells and in Burkitt lymphoma lines

Spontaneous apoptosis in germinal-centre (GC) B cells can be prevented by treatment with anti-immunoglobulin (Ig). By contrast, susceptible group-I Burkitt lymphoma (BL) cells can be driven to apoptosis by anti-Ig. The second-messenger pathways involved in the regulation of apoptosis in GC B lymphocytes and in BL cell lines were studied using pharmacological agonists or inhibitors of intracellular calcium ([Ca2+]i) and protein kinase C (PKC). Anti-Ig was found to mobilize Ca2+ in group-I cells. Pre-incubation with the Ca2+ chelator EGTA partially reduced apoptosis induced by anti-Ig or by Ca2+ ionophore in group-I BL cells. Activation of PKC with phorbol ester reduced such Ca(2+)-driven programmed cell death (PCD) to control levels of apoptosis. Apoptosis in group-I BL cell lines could also be triggered by the kinase inhibitors staurosporine and Ro-31-8220 at concentrations selective for PKC activity. Expression of the bcl-2 protein in BL group-I cells following gene transfer affords protection from apoptosis induced by ionomycin or anti-Ig. In the present study, bcl-2 was additionally found to protect from apoptosis driven by staurosporine. The high levels of spontaneous apoptosis exhibited by normal GC B cells were reduced, but not abrogated, by co-culture with phorbol ester. These results indicate that, in group-I BL cells, imbalance in the phosphoinositide pathway of signalling, in favour of [Ca2+]i and away from PKC, results in apoptosis: constitutive phosphorylation of key proteins by PKC may therefore suppress apoptosis in BL as well as in GC B cells.

p53 overexpression correlates with increased survival in patients with squamous carcinoma of the tongue base

Epidermal growth factor receptor (EGFR), transforming growth factor alpha (TGFA), and p53 are frequently overexpressed in squamous cell carcinomas (SCC) of the upper aerodigestive tract. We chose to study SCC of the tongue base, which is often advanced at presentation and fatal, to evaluate whether overexpression correlates with survival. Complete follow-up was available for 20 patients, 18 of whom had stage III or IV disease. A number of clinical (age, sex, stage of disease) and histologic (tumor grade, keratinization, mitotic rate, perineural invasion, lymphatic invasion, vascular invasion, host response) variables were analyzed. None of these variables correlated with survival. Immunohistochemical analysis was performed on paraffin-embedded tissue from each patient. Because EGFR and TGFA expression were routinely found in normal squamous epithelium, overexpression was considered present if greater uptake of the antibody was manifested by a deeper immunostain. In contrast, p53 oncoprotein was not detected in normal epithelium, so detection of the antibody was believed to indicate overexpression. EGFR was overexpressed in 60% of tumors, TGFA in 35%, and p53 in 20%. Those patients who had an overexpression of p53 had a greater mean survival than those who did not (48 versus 16 months, respectively, p = 0.06). This difference was significant for patients with clinical stage IV lesions (p = 0.03). EGFR overexpression and TGFA overexpression did not correlate with survival. p53 may serve as a biologic marker indicative of improved survival potential.

Bayesian estimation of streptomycin pharmacokinetics

Streptomycin dose requirements were determined in an 83-year-old man with renal impairment who was being treated for miliary tuberculosis. Concentration measurements were interpreted using a Bayesian parameter estimation program. Estimated creatinine clearance (1.1 L/h) was used as a starting value for streptomycin clearance, and volume was initially assumed to be 0.3 L/kg. Bayesian estimates of clearance were close to the starting value and declined from 1.4 L/h to 0.9 L/h during the course of therapy. Volume was higher than the initial estimate (0.4-0.5 L/kg), possibly due to the patient having a low albumin and being underweight. Satisfactory concentrations were maintained for several weeks with doses of 500 mg every 36-48 h.

Ligation of CD23 triggers cAMP generation and release of inflammatory mediators in human monocytes

Transduction through the CD23 molecule (Fc epsilon RII) was analyzed in normal human monocytes using monoclonal antibodies to CD23 (MHM6 and 135) and IgE/anti-IgE immune complexes. Monocytes expressing an increased amount of CD23 molecules were obtained by stimulation with IL-4 (30 U/ml). Anti-CD23 mAb as well as IgE/anti-IgE immune complexes were unable to induce any significant calcium mobilization [Ca2+]i in CD23-bearing monocytes whereas they elicited [Ca2+]i increase in B lymphocytes of the same donors. Despite their failure to induce calcium mobilization, the same CD23 ligands triggered a dose-dependent increase of intracellular cAMP, with a maximum 20 to 30 min after the onset of stimulation. This effect is mediated via CD23 inasmuch as: 1) F(ab)'2 fragments are as active as intact anti-CD23 mAb and 2) it is not observed in CD23- monocytes. The increase in cAMP was only partially altered in the presence of 1 microM indomethacin suggesting that it was not due to the release of PG. The possible role of CD23 in the activation of human monocytes was next documented by showing that anti-CD23 mAb and IgE/anti-IgE immune complexes induced the generation of IL-6 and of thromboxane B2 by CD23+ but not by CD23- monocytes. In addition, the IgE/anti-IgE-induced IL-6 production was potentiated in the presence of cAMP inducer such as the beta 2-adrenoceptor agonist salbutamol. These results indicate that ligation of CD23 induces cAMP generation in CD23+ human monocytes and that CD23 may regulate the IgE-dependent functions in normal human monocytes.

Ligation of CD23 triggers cAMP generation and release of inflammatory mediators in human monocytes

Transduction through the CD23 molecule (Fc epsilon RII) was analyzed in normal human monocytes using monoclonal antibodies to CD23 (MHM6 and 135) and IgE/anti-IgE immune complexes. Monocytes expressing an increased amount of CD23 molecules were obtained by stimulation with IL-4 (30 U/ml). Anti-CD23 mAb as well as IgE/anti-IgE immune complexes were unable to induce any significant calcium mobilization [Ca2+]i in CD23-bearing monocytes whereas they elicited [Ca2+]i increase in B lymphocytes of the same donors. Despite their failure to induce calcium mobilization, the same CD23 ligands triggered a dose-dependent increase of intracellular cAMP, with a maximum 20 to 30 min after the onset of stimulation. This effect is mediated via CD23 inasmuch as: 1) F(ab)'2 fragments are as active as intact anti-CD23 mAb and 2) it is not observed in CD23- monocytes. The increase in cAMP was only partially altered in the presence of 1 microM indomethacin suggesting that it was not due to the release of PG. The possible role of CD23 in the activation of human monocytes was next documented by showing that anti-CD23 mAb and IgE/anti-IgE immune complexes induced the generation of IL-6 and of thromboxane B2 by CD23+ but not by CD23- monocytes. In addition, the IgE/anti-IgE-induced IL-6 production was potentiated in the presence of cAMP inducer such as the beta 2-adrenoceptor agonist salbutamol. These results indicate that ligation of CD23 induces cAMP generation in CD23+ human monocytes and that CD23 may regulate the IgE-dependent functions in normal human monocytes.

In-vitro evaluation of povidone-iodine and chlorhexidine against methicillin-resistant Staphylococcus aureus

The in-vitro activity of povidone-iodine (PVP-I) and chlorhexidine (CHX) against 33 clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) was evaluated by a quantitative suspension test method. Bactericidal potency was measured by the logarithmic reduction factors (LRFs) achieved with each strain, tested at dilutions 25-800 over exposure times 30-300 s using a challenge of approximately 10(7) colony forming units (cfu) ml-1. The mean LRFs achieved over all dilutions, times and strains were significantly higher for PVP-I than CHX. PVP-I exhibited a superior killing effect whether measured by rate of kill or final LRF achieved. This difference was highly significant as judged by analysis of variance (P less than 0.001). Full efficacy of an antiseptic has been defined as a safe LRF greater than five. Over the dilution range 25-200 this was achieved by CHX with only three of 33 strains. In contrast, PVP-I achieved full efficacy with all 33 strains.

Factors modifying survival pathways of germinal center B cells. Glucocorticoids and transforming growth factor-beta, but not cyclosporin A or anti-CD19, block surface immunoglobulin-mediated rescue from apoptosis

The tendency for germinal center (GC) B cells to enter apoptosis is suppressed on engaging antigen receptor with immobilized anti-immunoglobulin; cross-linking of surface CD40 by monoclonal antibodies provides an additional signal for rescuing GC cells from programmed death. These observations are believed to reflect events that, in vivo, would allow for the selection of centrocytes which have undergone somatic mutation on Ig V-region genes to generate antigen receptor of high affinity. The purpose of the present study was to identify factors capable of modifying the survival pathways of GC cells. Transforming growth factor-beta, at an optimal concentration of 1 ng/ml, was found to inhibit surface immunoglobulin (sIg)-mediated rescue of GC cells but had no influence on survival promoted through CD40. Both routes of rescue were blocked by the glucocorticoid prednisolone at pharmacological concentrations (ID50 = 10(-7) M). Cyclosporin A, an antagonist of sIg-mediated signaling in resting B cells, failed to block rescue of GC cells through either of the receptor-activated pathways. Antibody to CD19--which also suppresses the activation of resting B cells--not only left GC cell rescue undiminished, but rather provided a modest survival signal of its own; interferon-alpha behaved similarly while interferon-gamma failed to influence GC cell survival in either direction.

Lack of [3H]quinuclidinyl benzylate binding to biologically relevant binding sites on mononuclear cells

We analyzed the binding characteristics of [3H]quinuclidinyl benzylate ([3H]QNB), a muscarinic cholinergic ligand, to rat and human mononuclear cells (MNC). Under various assay conditions, atropine-sensitive, saturable binding occurred with an apparent Kd of 10 nM. Conditions which disrupted the MNC membrane reduced total binding and eliminated specific binding. Muscarinic agonists were unable to inhibit [3H]QNB binding to MNC at concentrations up to 10(-2) M. Stereoisomers dexetimide and levetimide were equipotent inhibitors of binding (IC50 2 x 10(-5) M). We conclude that, although atropine-sensitive binding of [3H]QNB to MNC occurs, the binding is not consistent with the presence of a biologically relevant muscarinic cholinergic receptor.

Occupancy of CD72 (the CD5 counterstructure) enhances interleukin-4-dependent CD23 expression in resting B lymphocytes

CD72, the human homologue of murine Lyb-2, was recently identified as a counterstructure to CD5. An antibody to CD72 (BU40) has been found to mimic interleukin-4 (IL-4) both in its ability to activate resting B cells into the early G1 phase of cell cycle and to augment the expression of major histocompatibility complex (MHC) class II antigen; unlike IL-4, the CD72-clustered antibody fails to induce the expression of CD23. We now report that engagement of CD72 by the IgG monoclonal antibody BU40 potentiates the capacity of IL-4--when used at optimal concentrations--to promote CD23 production in human B cells. The degree of enhancement arising from occupancy of CD72 ranged from two- to fivefold. Importantly, antibody to CD72 was also found to diminish the concentration required for IL-4 to promote CD23 expression to a level equivalent to that maximally achieved when using IL-4 alone. Engagement of CD72 by BU40 not only increased the amount of cell-associated CD23 induced by IL-4 but also led to augmented release of soluble material into the culture medium. Monovalent Fab fragments of BU40 antibody were as efficient as intact antibodies at synergizing with IL-4 for enhanced expression and release of CD23: thus simple tethering without the need for receptor cross-linking was sufficient to invoke change through CD72. Enhancement of CD23 expression via CD72 appeared to be selective for IL-4-dependent induction: the turn on of CD23 by tumour-promoting phorbol ester was left unaltered on the addition of BU40 antibody. Engagement of CD72 had no effect on the IL-4-promoted hyperexpression of surface IgM. The findings are discussed within the context of the molecular and functional interactions occurring during T-B collaboration.

Enhancing in vitro fertilization of mouse oocytes by partial zona pellucida digestion

This work was undertaken in order to evaluate the effect of partial zona digestion on fertilization in vitro of mouse oocytes and assess zona surface changes induced by the procedure. Three hundred forty-six oocytes allocated for treatment were exposed to Ham's F-10 medium supplemented with 0.5% Pronase for either 3 min (188 oocytes) or 5 min (158 oocytes); 324 oocytes served as controls. Oocyte losses incurred as a result of the procedure were small (15 oocytes; 4.3%). Control and Pronase-treated oocytes were each divided into four subgroups and inseminated with 5 x 10(5), 5 x 10(4), 5 x 10(3), or 5 x 10(2) sperm cells/ml. Fertilization was assessed 8 hr following insemination by the appearance of two pronuclei and development to the two- to four-cell stage the following day. The morphology of the zona pellucida following Pronase treatment was assessed by phase-contrast and scanning electron (SEM) microscopies performed immediately after treatment. Fertilization rate of control oocytes was 80% at a sperm concentration of 500,000/ml and gradually declined to approximately 30% at 500 cells/ml. In contrast, treated oocytes inseminated with 500 sperm cells/ml demonstrated a normal rate of fertilization. At this low sperm concentration the longer Pronase treatment was significantly (P less than 0.05) more efficient in enhancing fertilization (69 and 88% for 3 and 5 min of Pronase treatment, respectively). Polyspermic fertilization was not observed in any of the subgroups. Phase-contrast microscopic examination of oocytes at the time of Pronase treatment showed an initial swelling of the zona pellucida for 30-60 sec with a time-dependent increase in its transparency.