Central Role for Interleukin-4 in Regulating Nitric Oxide-Mediated Inhibition of T-Cell Proliferation and Gamma Interferon Production in Schistosomiasis

Schistosoma mansoni-infected wild-type (WT) mice develop a Th2 response and chronic disease. In contrast, infected interleukin-4 double-deficient (IL-4(-/-)) mice develop a Th1-like response and an acute, lethal syndrome. Disease severity in these animals correlates with excessive and prolonged production of nitric oxide (NO) associated with enhanced antigen-driven gamma interferon (IFN-gamma) production in the absence of IL-4. Strikingly, splenic lymphocytes from infected IL-4(-/-) mice failed to proliferate as well as those from infected WT mice following stimulation in vitro with antigen or anti-CD3 antibody. Contrary to antigen-driven IFN-gamma responses, anti-CD3 antibody stimulation of splenocytes resulted in significantly less IFN-gamma being produced by CD8 cells from infected IL-4(-/-) mice than by those from infected WT mice or normal mice. NO is largely responsible for the impaired T-cell functions in infected IL-4(-/-) mice, as inhibition of iNOS significantly enhanced proliferation and IFN-gamma production.     

Antigen presentation by macrophages is enhanced by the uptake of necrotic, but not apoptotic, cells

The aim of this study was to determine whether phagocytosis of necrotic or apoptotic cells affects antigen presentation by murine bone marrow-derived macrophages. After uptake of necrotic neutrophils, macrophages were able to stimulate significantly higher T cell proliferation in vitro against both the recall antigen albumin and the mitogen concanavalin A. No such effect was seen following phagocytosis of apoptotic neutrophils. Flow cytometry revealed that, within 4h of ingestion, macrophages that had taken up the necrotic cells expressed higher levels of CD40 than those that had phagocytosed apoptotic cells. Macrophage cultures pulsed with apoptotic, but not necrotic, neutrophils contained higher levels of transforming growth factor beta1, but lower concentrations of tumour necrosis factor alpha, compared to untreated controls. Our interpretation of these results is that macrophages that have taken up necrotic neutrophils co-stimulate T cells with greater efficiency due to rapid CD40 up-regulation, whereas those that have ingested apoptotic cells are not only ineffective in co-stimulation, but also secrete inhibitory cytokine.     

Effect of cyclic AMP on histamine release induced by compound 48/80.

Bu2 cAMP(N6, O2'-dibutyryl adenosine-3',5'-cyclic monophosphate) inhibited the response of rat peritoneal mast cells to compound 48/80 in the presence of calcium ions. In the absence of calcium, the nucleotide partially prevented the desensitization induced by chelating agents. The response of cells, allowed to accumulate Bu2 cAMP in the presence of calcium (to avoid depletion of intracellular stores of the ion) and then challenged in the absence of extracellular calcium, was also inhibited. These results are discussed in terms of the postulated effects of Bu2 cAMP on the calcium-gatubg mechanism operative in histamine secretion.     

Detection of somatic mutations in man: evaluation of the microtitre cloning assay for T-lymphocytes

A method of detecting 6-thioguanine-resistant lymphocytes bythe cloning of T-lymphocytes in microtitre wells is evaluatedfor its usefulness in population monitoring. Factors shown toaffect the cloning efficiency of lymphocytes include the strainand irradiation level of the lymphoblastoid feeder cells andthe use of a pre-incubation period in bulk culture without mitogenicstimulus before plating at limiting dilutions. Cord blood sampleshave markedly lower mutant frequencies than adult blood samples.The adult range was 8.0 x 10^–7 to 1.8 x 10^–5. Sevenmales and seven females aged between 23 and 47 years were sampled.No effect of sex or age was found. Individual samples whichwere divided at collection and treated separately did not varyfrom each other, but repeat samples taken at different timesshowd up to a 2-fold variation. The application of this methodin population monitoring is discussed.     

Short term dynamic psychotherapy goes to Hollywood: the treatment of performance anxiety in cinema

This article uses characters in popular films to demonstrate the theory and application of short term dynamic psychotherapy (STDP) in the treatment of performance anxiety. The reader is taught to identify affect phobias that are hypothesized to underlie performance anxiety. Similar in function to external phobias, affect phobias or internal phobias involve the avoidance of feelings (e.g., fear about feeling anger, shame about showing grief, pain about closeness), which thwarts adaptive responding and generates numerous behavioral problems. STDP treatment focuses on the restructuring of defenses, conflicted affects, and attachments. The resolution of the affect phobia requires systematic desensitization of affective responses (i.e., exposure and desensitization of underlying conflicted feelings). When patients learn to access adaptive forms of feelings, performance anxiety can often be resolved.     

Allele variations in the OCA2 gene (pink-eyed-dilution locus) are associated with genetic susceptibility to melanoma

The occuloalbinism 2 (OCA2) gene, localized at 15q11, encodes a melanosomal transmembrane protein that is involved in the most common form of human occulo-cutaneous albinism, a human genetic disorder characterized by fair pigmentation and susceptibility to skin cancer. We wondered whether allele variations at this locus could influence susceptibility to malignant melanoma (MM). In all, 10 intragenic single-nucleotide polymorphisms (SNPs) were genotyped in 113 patients with melanomas and in 105 Caucasian control subjects with no personal or family history of skin cancer. By comparing allelic distribution between cases and controls, we show that MM and OCA2 are associated (p value=0.030 after correction for multiple testing). Then, a recently developed strategy, the 'combination test' enabled us to show that a combination formed by two SNPs was most strongly associated to MM, suggesting a possible interaction between intragenic SNPs. In addition, the role of OCA2 on MM risk was also detected using a logistic model taking into account the presence of variants of the melanocortin 1 receptor gene (MC1R, a key pigmentation gene) and all pigmentation characteristics as melanoma risk factors. Our data demonstrate that a second pigmentation gene, in addition to MC1R, is involved in genetic susceptibility to melanoma.     

Astrocyte glutamate receptor activation promotes inositol phospholipid turnover and calcium flux

Astrocyte-enriched cultures prepared from the neonatal rat cortex were prelabelled with either [3H]myoinositol or 45Ca2+ and then exposed to various excitatory amino acids. This resulted in an increase in both the breakdown of membrane inositol phospholipids and Ca2+ flux with the following rank order of efficacy: quisqualate greater than or equal to glutamate (Glu) greater than kainate much greater than N-methyl-D-aspartate. Experiments performed with the Ca2+ ionophore A23187 and in the absence of medium Ca2+ suggested that Glu-evoked 45Ca2+ efflux was primarily the result of an increased influx of extracellular Ca2+. However, Glu-stimulated inositol lipid metabolism was found to be only partially dependent on extracellular Ca2+. The quisqualate-preferring receptor antagonist gamma-glutamylaminomethylsulphonic acid was found to be effective in reversing both Glu-evoked inositol lipid breakdown and Ca2+ flux. The results presented are suggestive of some form of interaction between Glu receptors coupled to inositol lipid turnover and Ca2+ channel opening in astrocytes.     

The clinical pharmacokinetics of the novel antifolate N10-propargyl-5,8-dideazafolic acid (CB 3717)

Summary The pharmacokinetics of the new antifolate CB 3717 were studied in 20 patients during its phase-I clinical evaluation. The drug was administered at doses of 100–550 mg/m² in 1-h and 12-h infusions, resulting in peak plasma concentrations of CB 3717 of 40–200 M. There was a linear relationship between the dose and both CB 3717 AUC and peak plasma levels. Following a 1-h infusion, drug levels in the plasma decayed biphasically (t_1/2=49±9 min, t_1/2=739±209 min). 27%±2% of the dose was excreted in urine in the 24-h period after treatment, suggesting that the major route of elimination was via the bile. Furthermore, the parent compound CB 3717 and its desglutamyl metabolite, CB 3751, were found in a faecal collection although the metabolite was not detected in plasma or urine samples. Plasma protein binding of CB 3717 was extensive (97.6%±0.1%). Significant quantities of CB 3717 penetrated into ascitic fluid but not into cerebrospinal fluid.Residual drug was detected in postmortem kidney tissue from a patient who died of progressive disease 8 days after treatment with 330 mg/m² CB 3717. Thus, dose-limiting renal toxicity (maximum tolerated dose 600 mg/m²) may be due to drug precipitation in the renal tubules. Elevation of liver enzymes, in particular transaminases, occurred frequently as a toxic manifestation of CB 3717 therapy. In 11 patients studied after their first treatment there was a positive correlation between the rise in serum alanine transaminase and peak drug levels (r=0.69, P=0.02)These pharmacokinetic studies have shown that, by analogy with experimental systems, cytotoxic plasma levels of CB 3717 are archieved in man. In addition, they have been valuable in interpreting toxicities observed during phase-I clinical studies.This work was supported by grants from the Medical Research Council and Cancer Research Campaign, U. K.