Co-chairman's remarks: genetic recombination in the molecular era

The present status of some general questions about DNA recombination is assessed. Topics include the mechanisms of synapsis and strand exchange, and the functions of recombination in nature.

Genome organization in prokaryotes

Most of the well-characterized prokaryotic genomes consist of double-stranded DNA organized as a single circular chromosome 0.6-10 Mb in length and one or more circular plasmid species of 2 kb-1.7 Mb. The past few years, however, have revealed some major variations in genome organization. In addition, a recent accumulation of data has shown that the location and orientation of the genes and repeated sequences (including prophages and transposons) on and among these elements is not always random. Some of the non-randomness is probably the result of unique historical events; in other cases it reflects selection for the optimization of function.

Human bronchial epithelial cell dysfunction following in vitro exposure to nitrogen dioxide

Nitrogen dioxide (NO2), is a major air pollutant, that causes bronchoconstriction and bronchial hyperreactivity, and may also lead to damage and inflammation of the airway epithelium. We have cultured human bronchial epithelial cells and investigated the effect of exposure to NO2, for 20 min on epithelial cell membrane integrity and function in vitro. Epithelial cell membrane damage and permeability were assessed by release of 51Cr from prelabelled cells, and movement of 14C-labelled bovine serum albumin (BSA) across the bronchial epithelial cell monolayers. Ciliary beat frequency (CBF) of the cells was monitored by the analogue contrast enhancement technique, and arachidonic acid (AA) metabolism was investigated by analysis of radiolabelled AA metabolites generated from cultures prelabelled by incubation with [3H]-arachidonic acid. Exposure to 400 and 800 parts per billion (ppb) NO2 significantly increased the release of 51Cr from 0.9 +/- 0.4%, in control cultures exposed to 5% CO2 in air, to 9.7 +/- 3.2% and 13.9 +/- 3.5%, respectively. Similarly, NO2 also significantly increased the movement of 14C-BSA across the epithelial monolayers from 1.3 +/- 0.2%, in control cultures, to 2.7 +/- 0.2%, 3.8 +/- 0.4% and 5.1 +/- 0.5%, respectively, in cultures exposed to 100, 400 and 800 ppb NO2. Although NO2 attenuated the CBF of the cells at all concentrations investigated, this was significant only at the concentration of 2,000 ppb NO2.(ABSTRACT TRUNCATED AT 250 WORDS)

Human bronchial epithelial cell dysfunction following in vitro exposure to nitrogen dioxide

Nitrogen dioxide (NO2), is a major air pollutant, that causes bronchoconstriction and bronchial hyperreactivity, and may also lead to damage and inflammation of the airway epithelium. We have cultured human bronchial epithelial cells and investigated the effect of exposure to NO2, for 20 min on epithelial cell membrane integrity and function in vitro. Epithelial cell membrane damage and permeability were assessed by release of 51Cr from prelabelled cells, and movement of 14C-labelled bovine serum albumin (BSA) across the bronchial epithelial cell monolayers. Ciliary beat frequency (CBF) of the cells was monitored by the analogue contrast enhancement technique, and arachidonic acid (AA) metabolism was investigated by analysis of radiolabelled AA metabolites generated from cultures prelabelled by incubation with [3H]-arachidonic acid. Exposure to 400 and 800 parts per billion (ppb) NO2 significantly increased the release of 51Cr from 0.9 +/- 0.4%, in control cultures exposed to 5% CO2 in air, to 9.7 +/- 3.2% and 13.9 +/- 3.5%, respectively. Similarly, NO2 also significantly increased the movement of 14C-BSA across the epithelial monolayers from 1.3 +/- 0.2%, in control cultures, to 2.7 +/- 0.2%, 3.8 +/- 0.4% and 5.1 +/- 0.5%, respectively, in cultures exposed to 100, 400 and 800 ppb NO2. Although NO2 attenuated the CBF of the cells at all concentrations investigated, this was significant only at the concentration of 2,000 ppb NO2.(ABSTRACT TRUNCATED AT 250 WORDS)

Activation by histamine of bronchial epithelial cells from nonasthmatic subjects

Histamine is a major mediator of the mast cells that are present between epithelial cells in asthma. In asthma, there is an increased expression of ICAM-1 and HLA-DR and an increased spontaneous release of fibronectin. The effect of histamine was tested on bronchial epithelial cells obtained by bronchial brushing from 22 nonasthmatic subjects. The activation of epithelial cells was assessed by immunocytochemical analysis of the expression of membrane markers (ICAM-1 and HLA-DR) using the alkaline phosphatase-anti-alkaline phosphatase method and the release of fibronectin (enzyme immunoassay). Time-response (three experiments) and dose-response (six experiments) curves showed that the maximal effect was obtained after an incubation time of 24 h and a dose of 1 microM of histamine. For this time course and concentration, there was a highly significant increase in the number of cells expressing ICAM-1 (before histamine: 10 +/- 11%; after histamine: 32 +/- 20%; P < 0.001) and HLA-DR (before histamine: 8 +/- 7%; after histamine: 23 +/- 20%; P < 0.001) and in the release of fibronectin (before histamine: 30 +/- 20 ng/10(5) viable cells; after histamine: 61 +/- 35 ng/10(5) viable cells; P < 0.003). Cycloheximide blocked these effects, suggesting that histamine requires protein synthesis for its action. Pyrilamine (H1-blocker) and ranitidine (H2-blocker) at a concentration of 10 microM decreased the effect of histamine. However, there was no additive effect when both antagonists were added. This study suggests that mast cells present in the airways have a role in the activation of epithelial cells.

Effect of nitrogen dioxide on synthesis of inflammatory cytokines expressed by human bronchial epithelial cells in vitro

Although studies of nitrogen dioxide (NO2) inhalation, in both animals and humans, have demonstrated that this agent can cause epithelial cell damage and inflammation of the airway epithelium, the mechanisms underlying these effects are not well understood. We have cultured human bronchial epithelial cells, as explant cultures from surgical tissue, and studied these firstly from their ability to constitutively synthesize specific proinflammatory cytokines and then investigated the effect of exposure to NO2 on the generation of these cytokines. Constitutive synthesis of cytokines was evaluated by analysis of both the expression of the mRNA for interleukin (IL)-1 beta, IL-4, IL-8, granulocyte/macrophage colony-stimulating factor (GM-CSF), tumor necrosis factor-alpha (TNF-alpha), and interferon-gamma (IFN-gamma), by the polymerase chain reaction (PCR), and by immunocytochemical staining for the presence of cell-associated IL-1 beta, IL-8, GM-CSF, TNF-alpha, and IFN-gamma, using specific monoclonal and polyclonal antibodies directed towards these cytokines. Release of IL-4, IL-8, GM-CSF, TNF-alpha, and IFN-gamma following exposure to 5% CO2 in air or 400 ppb and 800 ppb NO2 for 6 h was investigated by enzyme-linked immunosorbent assay. PCR demonstrated that the human bronchial epithelial cells expressed the mRNA for IL-1 beta, IL-8, GM-CSF, and TNF-alpha but not for IL-4 and IFN-gamma. Immunocytochemical staining confirmed the presence of endogenous IL-1 beta, IL-8, GM-CSF, and TNF-alpha.(ABSTRACT TRUNCATED AT 250 WORDS)

HLA-DR and ICAM-1 expression on bronchial epithelial cells in asthma and chronic bronchitis

HLA-DR and ICAM-I molecules play an important role in cellular interactions, and their expression can be induced by inflammatory stimuli. We evaluated the spontaneous expression of HLA-DR and ICAM-1 on epithelial cells obtained by bronchial brushing from 27 asthmatic patients, 10 chronic bronchitis (CB) patients, and 19 normal subjects. In all cases > 90% pure epithelial cells were obtained. HLA-DR and ICAM-1 were characterized using monoclonal antibodies and revealed by immunocytochemistry (APAAP technique). In asthma, the percentage of cells expressing HLA-DR and ICAM-1 was significantly increased by comparison with normal values (p < 0.001) and GB (p < 0.001; HLA-DR; p < 0.003; ICAM-1) and was correlated with the clinical score of Aas (p < 0.001, HLA-DR; p < 0.001, ICAM-1) and the FEV1 (p < 0.001, HLA-DR; p < 0.002; ICAM-1). In CB, expression of both markers was slightly but significantly increased by comparison with normal subjects and was correlated with FEV1 (p < 0.02, HLA-DR; p < 0.03, ICAM-1). In addition, the expression of HLA-DR and ICAM-1 was significantly correlated. This study suggests that epithelial cells are in an activated state in asthma and that the extent of expression of these markers may be specific to asthma, not a general feature of chronic inflammation.

Conjunctival provocation tests with codeine phosphate. Effect of disodium cromoglycate

The reactivity of ocular mast cells is poorly characterized in man. Provocation tests with codeine phosphate, a molecule known to activate connective tissue mast cells, were performed in ten normal subjects. Ten-fold increasing concentrations of codeine phosphate (10(-5) to 10(-1) mg/mL) were tested in both eyes until a positive challenge was observed. Schirmer strips were placed under the eyelid and left for five minutes. A negative control was performed ten days later. All subjects had a strongly positive reaction for the same codeine phosphate concentration (10(-1) mg/mL). Histamine was released in 8/10 subjects (control: 7.06 +/- 4.19 nM/L, codeine phosphate: 18.2 +/- 15.7 nM/L, P < .018), PGD2 was released in 8/10 subjects (control: 0 codeine phosphate: 273.3 +/- 408.9 ng/L). Disodium cromoglycate blocked the release of histamine and PGD2. Codeine phosphate is potent at causing mast cell activation in the eye and this effect is blocked by disodium cromoglycate.

Precision of conjunctival provocation tests in right and left eyes

BACKGROUND

Conjunctival provocation tests (CPTs) are used for assessing the efficacy of antiallergic treatments, but their reproducibility is not well characterized. A study was carried out to assess the reproducibility of CPTs and the release of mediators during CPTs.

METHODS

Both eyes of 30 grass-pollen-allergic patients were challenged with threefold increasing concentrations of a standardized orchard grass pollen extract. The positivity of the CPT was assessed by a cumulative symptom score. The release of mediators was examined by means of histamine (radioimmunoassay), prostaglandin D2 and leukotrienes C4 and D4 (enzyme immunoassay).

RESULTS

There was a significant correlation between the concentrations of allergen inducing a positive CPT in both eyes (p < 0.0001, Spearman). All but one patient had a significant release of at least one mediator. After allergen CPT there was a significant release in both eyes in 13 of 20 patients for prostaglandin D2, 11 of 19 for leukotrienes C4 and D4 and 15 of 18 for histamine. The correlations between the levels of mediators released during diluent and allergen challenges in both eyes were significant for prostaglandin D2 (diluent and allergen challenges) and leukotrienes C4 and D4 (allergen challenge).

CONCLUSION

Considering the whole group of patients, CPT is reproducible in both eyes, but the results are less satisfactory when patients are examined individually.

Functional and phenotypic characteristics of bronchial epithelial cells obtained by brushing from asthmatic and normal subjects

Bronchial epithelial cells may be involved in the pathogenesis of asthma releasing several inflammatory mediators such as interleukins and lipoxygenase products. In this study we evaluated the spontaneous and A23128-induced release of 15-HETE, PGE2 and fibronectin as well as the spontaneous expression of HLA-DR and ICAM-1 molecules by bronchial epithelial cells obtained by bronchial brushing from 35 asthmatic and 27 normal subjects. The release of fibronectin and 15-HETE was studied using the EIA and RIA techniques. The expression of HLA-DR and ICAM-1 molecules was studied using the APAAP and the immunofluorescence methods. Bronchial epithelial cells from asthmatics released higher amounts of 15-HETE and fibronectin both spontaneously (p < 0.002, p < 0.05, respectively) or after stimulation with calcium ionophore compared with normals. On the other hand, PGE2 release was significantly higher only after stimulation with calcium ionophore (p < 0.002). The spontaneous expression of HLA-DR and ICAM-1 (p < 0.001) was significantly higher on epithelial cells from asthmatics than in normal subjects. Finally, the severity of asthma significantly correlated with the release of 15-HETE (p < 0.02) and the expression of HLA-DR and ICAM-1 respectively (p < 0.001 and p < 0.002, respectively). This study indicates that bronchial epithelial cells are in an activated state in asthma and that the degree of activation is correlated to the severity of the disease.

Differential distribution of the alternative forms of the sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPase, SERCA2b and SERCA2a, in the avian brain

Cellular distribution of the two forms of SERCA2 was examined in adult chicken brain. Four regions of the brain were analyzed with three immunological reagents: a monoclonal antibody that recognizes both forms of SERCA2, and two antisera which are specific for the two alternative forms, SERCA2b or SERCA2a. Cerebellar Purkinje cells express predominantly SERCA2b but also low levels of SERCA2a, as has been reported for mammals. The nucleus isthmo-opticus, nucleus magnocellularis cochlearis, and nucleus laminaris all express high levels of SERCA2 but with different ratios of SERCA2b and SERCA2a. These immunohistochemical results were supported by in situ hybridization analysis. Therefore, it appears that regions within the brain have specific requirements for the two forms of SERCA2. This suggests functional significance for the alternative forms SERCA2b and SERCA2a, and possible functions are discussed.

Altered lymphocyte populations in tumour invaded nodes of breast cancer patients

Lymphocytes from matched pairs of tumour-invaded and tumour-free lymph nodes from 22 stage II breast cancer patients have been analysed for expression of phenotypic and activation markers by flow cytometry. Although the relative proportions of T and B lymphocytes were similar in the two nodes, significant differences in the distribution of T cell subsets were observed between nodes that were invaded and those that were not. The CD4/CD8 ratio was markedly depressed in tumour invaded nodes (P < 0.001). This was due to an increase in the number of CD8+ T cells (P < 0.001) and a decrease in the CD4+ T cell population (P = 0.008) in invaded nodes in comparison with tumour-free nodes. The percentage of CD8+ T cells expressing HLA DR (P = 0.023) and IL-2 receptors (Tac) (P = 0.029) was significantly higher in invaded nodes and, while CD4+ T cells expressing HLA DR (P = 0.036) were also in a higher proportion of Tac expressing CD4+ T cells failed to reach significance. Although invaded nodes in a few patients were found to have a higher percentage of IgG-expressing B cells, no significant differences were observed between the two groups of nodes. These results suggest that the presence of metastatic tumour cells in a lymph node is associated with specific alterations in the T cell population.

Functional characteristics of bronchial epithelium obtained by brushing from asthmatic and normal subjects

Airways epithelial cells may be involved in the pathogenesis of asthma, but their role remains to be determined. Epithelial cells can release large amounts of 15-hydroxy-eicosatetranoic acid (15-HETE) and smaller amounts of prostaglandin E2 (PGE2) as well as fibronectin, a mediator involved in epithelial repair after injury. Epithelial cells obtained after bronchial brushing of 16 asthmatic (age 38 +/- 5 yr) and 11 normal subjects (age 36 +/- 5 yr) were studied. The percentage of epithelial cells was assessed by immunocytochemistry using an anti-cytokeratin antibody. The viability of the cells was assessed by trypan blue exclusion. The release of 15-HETE PGE2 and fibronectin was studied in resting cells and after A23187 calcium ionophore stimulation. Epithelial cells always comprised more than 86% of cells recovered, and the viability of epithelial cells was significantly (p < 0.001, Mann-Whitney U test) greater in normal subjects (54 +/- 5%) compared with asthmatic subjects (13 +/- 1%). The release of 15-HETE and fibronectin by resting epithelial cells was significantly greater in asthmatics (p < 0.05, Mann-Whitney U test) than in normal subjects. A23187 significantly (p < 0.05, Wilcoxon W test) increased the release of 15-HETE and fibronectin. There was no significant difference in the release of PGE2 by resting cells from either asthmatics or normal subjects, but challenge with A23187 induced a significant (p < 0.03, Wilcoxon W test) increase in PGE2 from cells of asthmatics but not from cells of normal subjects. This study shows that epithelial cells are activated and less viable in asthma and suggests a role for these cells in asthma.

Modulation of eicosanoid and histamine release from human dispersed lung cells by terfenadine

Terfenadine is an H1-blocker that may have antiallergic properties. A study was carried out to examine the ability of terfenadine to inhibit the release of histamine and arachidonic-acid-derived mediators from human lung cells. Cells were dispersed from fresh human lung tissue obtained from four accident victims whose hearts were donated for transplantation and four lung cancer resections. Cells were dispersed by enzymatic digestion with type XIV protease and chymopapain, and this resulted in a cell population containing approximately 5% mast cells. The remaining cells were mainly macrophages. The cells were challenged with anti-IgE at a 1/1000 dilution. Cells were challenged without terfenadine and after a preincubation of 0.1, 1, and 10 mumol terfenadine. The release of PGD2 and LTC4/D4 was assessed with an EIA. Histamine was assayed by RIA with a monoclonal antibody against acylated histamine. A release of both eicosanoids and histamine was observed in all experiments. An inhibition of eicosanoids was observed at both 1 and 10 mumol terfenadine (median percentage of inhibition of PGD2: 38.00 +/- 15.65 and 56.00 +/- 13.12; median percentage of inhibition of LTC4/D4: 37.5 +/- 19.80 and 52.5 +/- 26.8). On the other hand, histamine release was not blocked by terfenadine. Terfenadine inhibits, in a dose-dependent manner, the release of eicosanoids after challenge of dispersed lung cells by anti-IgE, and this effect may have some clinical relevance.

Characterization of the integrin specificities of disintegrins isolated from American pit viper venoms

A new series of homologous disintegrins was isolated from the venoms of new world pit viper genus Bothrops, Crotalus, and Lachesis. The relative activities of each disintegrin in blocking adhesive protein binding activities of GPIIb-IIIa, alpha v beta 3, and alpha 5 beta 1 were determined and correlated with their primary amino acid sequences. Four disintegrins contained the RGDW sequence and were found to be approximately twice as effective in blocking the binding of fibrinogen to GPIIb-IIIa than inhibiting the binding of vitronectin to alpha v beta 3 in solid-phase ligand binding assays (IC50 = 7.3 and 17.2 nM, respectively). A second group of seven disintegrins contained the RGDNP sequence and were found to be more potent inhibitors of vitronectin binding to alpha v beta 3 than fibrinogen binding to GPIIb-IIIa (IC50 = 4.3 and 19 nM, respectively). The RGDNP containing disintegrins were also greater than 10-fold more potent than RGDW containing disintegrins in blocking the adhesion of cells mediated by alpha 5 beta 1. These data illustrate that amino acid sequences immediately adjacent to the RGD site of disintegrins can create an extended RGD locus which coupled with conformational display of the RGD sequence may be involved in determining integrin selectivity and affinity. This information has been used in separate studies to design conformationally constrained integrin antagonists with high affinity for platelet GPIIb-IIIa.

Design of potent and specific integrin antagonists. Peptide antagonists with high specificity for glycoprotein IIb-IIIa

Members of the snake venon-derived, "disintegrin" peptide family containing the Arg-Gly-Asp (RGD) amino acid sequence are among the most potent inhibitors of the binding of adhesive proteins to platelet glycoprotein (GP) IIb-IIIa. However, GPIIb-IIIa antagonists containing the RGD sequence are not integrin specific and inhibit the adhesive functions of many other RGD-dependent integrins. The single disintegrin peptide, barbourin, containing a conservative amino acid substitution of Lys (K) for Arg (R) in the RGD sequence, is however, highly specific for GPIIb-IIIa. Using this information we have tested the hypothesis that both structural and conformational elements of barbourin are important for its high affinity and selectivity for platelet GPIIb-IIIa by synthesizing a series of conformationally constrained, disulfide-bridged peptides containing the KGD amino acid sequence. Incorporation of the KGD sequence into a cyclic peptide template, followed by systematic optimization of the cyclic ring size, optimization of secondary hydrophobic binding site interactions, and the derivatization of the lysyl side chain functionality of the KGD sequence has resulted in peptide analogs which display inhibitory potency and GPIIb-IIIa selectivity comparable to that of barbourin. This study demonstrates that the specificity and potency of the disintegrin family of antagonists, in particular barbourin, can be mimicked by small, conformationally restrained peptides.

Dual colour flow cytometry of p53 and c-erbB-2 expression related to DNA aneuploidy in primary and metastatic breast cancer

DNA aneuploidy and p53 or c-erbB-2 expression were simultaneously measured in 29 breast tumours by two-colour flow cytometry. (i) The majority of tumours had some cells expressing either p53 (5-68%) or c-erbB-2 (1-56%). (ii) Expression of p53 and c-erbB-2 was observed mainly in the aneuploid population of mixed aneuploid and diploid tumours but there was no significant correlation with a specific DNA index. Aneuploid tumours contained higher percentages of c-erbB-2 positive cells (average 25%) than purely diploid tumours (average 15%) but this just failed to reach significance (P = 0.074). No relevant trends were noted for p53 expression. (iii) Significantly increased c-erbB-2 expression was observed in stage 2 tumours (26%) compared to stage 1 tumours (12%) (P = 0.001) with no trend evident for p53 expression. (iv) The metastatic tumour in the axillary node contained similar or slightly higher percentages of positive cells than the matched primary tumour.

Anti-allergic activity of H1 blockers

Terfenadine is an H1 blocker that may also have anti-allergic properties, as it inhibits the release of mediators from mast cells. Oral terfenadine reduces the release of prostaglandin D2 (PGD2) and, to a lesser extent, the release of histamine in patients after nasal challenge with allergen. The effect of terfenadine on the release of mediators from mast cells isolated from human lung was examined. The cells were challenged with anti-immunoglobulin E after pretreatment with 0, 0.1, 1 or 10 microM terfenadine, and the release of PGD2, leukotriene C4/D4 and histamine was assessed. Release of both eicosanoids was observed in the absence of terfenadine. Inhibition of the release of both eicosanoids was seen with 1 and 10 microM terfenadine. The release of histamine was not affected by terfenadine. These anti-allergic properties of terfenadine are likely to be involved in the therapeutic efficacy of the drug.

c-fos proto-oncogene expression in bronchial biopsies of asthmatics

c-fos, a proto-oncogene regulating the transcription of many genes, plays a critical role in the cell cycle and differentiation and may be involved in the regulation of inflammation in asthma. Very low levels of c-fos are detectable in most human cells, and its expression is rapidly and transiently increased by multiple factors, some of which are involved in the airways inflammation of asthma (histamine, eicosanoids, and cytokines). The presence of c-fos protein, as detected by immunofluorescence, and the immunoreactivity of PCNA, a cell proliferation marker, were examined in bronchial biopsies obtained from 12 asthmatics and 10 normal subjects. Biopsies of eight of 12 asthmatics expressed c-fos versus none of 10 normal subjects. The expression was heterogeneous and localized to cells positive for anti-cytokeratin monoclonal antibody, indicating their epithelial origin. On the other hand, PCNA immunoreactivity was only observed in one asthmatic and one control subject but it was not related with c-fos expression. This study demonstrates the induction of c-fos in epithelial cells of asthmatics, suggesting a role for this proto-oncogene in activation rather than in proliferation.

Analysis of clonality of tumour infiltrating lymphocytes in breast cancer and uveal melanoma

Fresh tumour infiltrating lymphocytes (TILs) from 6 uveal melanomas and 4 breast cancers were analysed by flow cytometry with a panel of 6 monoclonal antibodies to V beta regions of the T cell receptor (V betas 5a, 5b, 5c, 6, 8a and 12a). With a single exception where one TIL sample lacked V beta 12a, lymphocytes from both tumour and blood contained cells reactive with all 6 probes, and no probe was highly dominant or missing. The proportions of reactive cells differed between tumour and blood within each patient. The data indicate that while tumour infiltrating lymphocytes have a capacity to locate selectively within the tumour they nonetheless comprise a population expressing a diversity of TCR V beta genes.

The alternative carboxyl termini of avian cardiac and brain sarcoplasmic reticulum/endoplasmic reticulum Ca(2+)-ATPases are on opposite sides of the membrane

The sarcoplasmic/endoplasmic reticulum slow-twitch or cardiac Ca(2+)-ATPase (SERCA2) is expressed as two forms (SERCA2a and SERCA2b) which vary at their extreme carboxyl termini. SERCA2a and SERCA2b are derived from alternatively spliced primary transcripts of the same gene. These two alternative carboxyl termini are highly conserved in mammals (Eggermont, J. A., Wuytack, F., De Jaegere, S., Nelles, L., and Casteels, R. (1989) Biochem. J. 260, 757-761; Lytton, J., and MacLennan, D. H. (1988) J. Biol. Chem. 263, 15024-15031) and birds (Campbell, A. M., Kessler, P. D., Sagara, Y., Inesi, G., and Fambrough, D. M. (1991) J. Biol. Chem. 266, 16050-16055). The topology of SERCA2a is believed to be identical to the fast-twitch Ca(2+)-ATPase (SERCA1) with 10 membrane-spanning domains. Based on hydropathy analysis, the extended carboxyl terminus of SERCA2b is predicted to span the endoplasmic reticulum (ER) membrane an additional (i.e. 11th) time. We have added the human c-myc epitope, a 10-amino acid sequence recognized by monoclonal antibody 9E10, onto the carboxyl termini of SERCA2a and SERCA2b to test whether or not their carboxyl termini are on the same side of the ER membrane. The added epitopes do not appear to disrupt topology as judged from unaltered Ca2+ transport. Immunocytochemical studies demonstrate that SERCA2a and SERCA2b have their carboxyl termini on opposite sides of the ER membrane; SERCA2a's is in the cytosol and SERCA2b's is in the ER lumen.

T cell receptor gamma/delta expression on lymphocyte populations of breast cancer patients

The quantitative distribution and phenotype of gamma/delta lymphocytes in the peripheral blood (PBL), tumour draining lymph node (LNL) and tumour infiltrating lymphocytes (TIL) from breast carcinoma patients were determined by one- and two-colour flow cytometry. The TCR-gamma/delta + cells generally expressed the T cell lineage antigen CD3. The proportions of such cells were variable but generally small from all the three sources. Phenotypic analysis revealed that the CD8 marker was consistently and predominantly observed on gamma/delta + CD3+ cells in the tumour infiltrate, whereas CD4 expression, while generally low, was noted on a significant percentage (median 10%) of LNL gamma/delta + lymphocytes. In both PBL and LNL the predominant gamma/delta cell population was CD4-8-.

Statistical analyses of counts and distributions of restriction sites in DNA sequences

Counts and spacings of all 4- and 6-bp palindromes in DNA sequences from a broad range of organisms were investigated. Both 4- and 6-bp average palindrome counts were significantly low in all bacteriophages except one, probably as a means of avoiding restriction enzyme cleavage. The exception, T4 of normal 4- and 6-palindrome counts, putatively derives protection from modification of cytosine to hydroxymethylcytosine plus glycosylation. The counts and distributions of 4-bp and of 6-bp restriction sites in bacterial species are variable. Bacterial cells with multiple restriction systems for 4-bp or 6-bp target specificities are low in aggregate 4- or 6-bp palindrome counts/kb, respectively, but bacterial cells lacking exact 4-cutter enzymes generally show normal or high counts of 4-bp palindromes when compared with random control sequences of comparable nucleotide frequencies. For example, E. coli, apparently without an exact 4-bp target restriction endonuclease (see text), contains normal aggregate 4-palindrome counts/kb, while B. subtilis, which abounds with 4-bp restriction systems, shows a significant under-representation of 4-palindrome counts. Both E. coli and B. subtilis have many 6-bp restriction enzymes and concomitantly diminished aggregate 6-palindrome counts/kb. Eukaryote, viral, and organelle sequences generally have aggregate 4- and 6-palindromic counts/kb in the normal range. Interpretations of these results are given in terms of restriction/methylation regimes, recombination and transcription processes, and possible structural and regulatory roles of 4- and 6-bp palindromes.

Over- and under-representation of short oligonucleotides in DNA sequences

Strand-symmetric relative abundance functionals for di-, tri-, and tetranucleotides are introduced and applied to sequences encompassing a broad phylogenetic range to discern tendencies and anomalies in the occurrences of these short oligonucleotides within and between genomic sequences. For dinucleotides, TA is almost universally under-represented, with the exception of vertebrate mitochondrial genomes, and CG is strongly under-represented in vertebrates and in mitochondrial genomes. The traditional methylation/deamination/mutation hypothesis for the rarity of CG does not adequately account for the observed deficiencies in certain sequences, notably the mitochondrial genomes, yeast, and Neurospora crassa, which lack the standard CpG methylase. Homodinucleotides (AA.TT, CC.GG) and larger homooligonucleotides are over-represented in many organisms, perhaps due to polymerase slippage events. For trinucleotides, GCA.TGC tends to be under-represented in phage, human viral, and eukaryotic sequences, and CTA.TAG is strongly under-represented in many prokaryotic, eukaryotic, and viral sequences. The CCA.TGG triplet is ubiquitously over-represented in human viral and eukaryotic sequences. Among the tetranucleotides, several four-base-pair palindromes tend to be under-represented in phage sequences, probably as a means of restriction avoidance. The tetranucleotide CTAG is observed to be rare in virtually all bacterial genomes and some phage genomes. Explanations for these over- and under-representations in terms of DNA/RNA structures and regulatory mechanisms are considered.

Aneuploid subpopulations in tumour-invaded lymph nodes from breast cancer patients

Fresh, paired primary tumours and lymph node metastases from breast cancer patients were compared by DNA flow cytometry. Although 65% of primary tumours were aneuploid, the detection of aneuploid peaks in corresponding nodal metastases was rare (only 6 cases out of 25) in single-parameter DNA analysis. Detection of aneuploid subpopulations in lymph nodes was greatly improved in dual-parameter DNA analysis using an anticytokeratin (CK) antibody which allowed ploidy determination on CK+ epithelial cells alone. Examination of 12 lymph nodes for CK+ cells revealed the presence of both diploid and aneuploid tumour cells in tumour invaded nodes. In patients with multiploid primary tumours, a subpopulation of the primary aneuploid cells was dominant in the nodal metastases. This suggests that aneuploidy is an integral property of metastatic cells and that within a primary tumour a subpopulation may have a higher metastatic potential.

Anaesthesia in a patient with Noonan's syndrome and cardiomyopathy

A 5-year-old girl with Noonan's syndrome and a hypertrophic cardiomyopathy presented for myelography and subsequently, laminectomy. The anaesthetic management of the patient is described and the potential problems of the facial, cardiovascular and skeletal abnormalities associated with the condition are discussed.

Flow cytometric analysis of tumour-draining lymph nodes in breast cancer patients

The phenotype and activation status of lymphocytes from the peripheral blood and axillary lymph nodes of 40 patients with breast cancer were analysed using flow cytometry and compared with lymphocytes from the blood and lymph nodes of 7 control subjects. There was little difference in the overall proportions of T and B lymphocytes but there was a much larger population of B cells bearing surface IgG and a greater number of CD4+ helper T cells, particularly in the regional nodes, in the breast cancer patients. Many more T cells in the cancer patients were found to be carrying the HLA DR and Tac antigens. The axillary lymph nodes were the major site of B cells and CD4+ T cells whilst the primary tumour was the source of the CD8+ suppressor/cytotoxic T cells. Any immune response appeared to be largely loco-regional and may therefore destroyed by conventional surgery or radiotherapy.

In vitro activation of bronchoalveolar lavage cells by house dust mite allergens

Mast cells represent a small but important proportion of bronchoalveolar lavage cells and are directly exposed to environmental triggers including allergens. Histamine and PGD2 are mediators released during the activation of mast cells. Fourteen patients allergic to Dermatophagoides pteronyssinus were studied. After bronchoalveolar lavage the unfractionated cell pellet containing metachromatic cells was submitted to allergen challenge using three concentrations of a standardized Dermatophagoides pteronyssinus extract and one concentration of A23187 (2.5 microM). The release of histamine was measured by radioimmunoassay using a monoclonal antibody against acylated histamine and PGD2 was measured by enzyme immunoassay using a polyclonal antibody against methoxamine-PGD2. Histamine was released in 13/14 patients following stimulation of the cells with A23187 and 12/14 patients after stimulation with Dermatophagoides pteronyssinus extract. The release of histamine was 3.5-fold greater when cells were stimulated by the Dermatophagoides pteronyssinus extract than with A23187. PGD2 was released in 10/12 patients when cells were stimulated with A23187 and 6/14 patients in the case of Dermatophagoides pteronyssinus extract stimulation. In the latter case, the mean release was not significantly greater than baseline. For histamine, the maximum release usually occurred with the more concentrated extract whereas in the experiments where PGD2 was released, maximal generation usually occurred with the lowest concentration used. There was no correlation between the severity of asthma and the release of mediators. This study confirms the activation of metachromatic cells by allergen and shows some heterogeneity in the release of granule and membrane-derived mediators.

Flow cytometric analysis of tumour infiltrating lymphocyte activation and tumour cell MHC class I and II expression in breast cancer patients

The primary tumour cells and tumour infiltrating lymphocytes (TILs) of 31 breast cancer patients have been analysed by dual colour flow cytometry to determine whether the phenotype and/or activation status of the TILs bears any relationship to the expression of MHC antigens on the tumour cells. The phenotype and activation status of 5000 TILs were studied using Mabs to CD4, CD8, HLA DR, CD25 (the low affinity inducible IL-2 receptor) and the transferrin receptor and related to Class I and Class II MHC expression on 5000 primary tumour cells. On the tumour cells, Class I MHC expression ranged from 1-74%, averaging 12.9%. HLA DR expression ranged from 1-69% averaging 14.3%. When the phenotypic proportions of the lymphocytic infiltrate were analysed there was found to be a correlation between tumour expression of Class I MHC and the proportion of both CD4+ (P less than 0.05) and CD8+ (P less than 0.02) T cells within the tumour. No such relationship was found with the MHC Class II antigen. When TIL activation markers were analysed, the percentage of CD8+ TILs positive for HLA DR expression correlated strongly with the expression of Class I (P less than 0.001) and Class II (P less than 0.001) antigens on the tumour cells. The percentage of CD4+ TILs positive for HLA DR expression also correlated significantly, but less strongly with the expression of Class I (P less than 0.01) and Class II (P less than 0.02) antigen expression on the tumour cells. The percentage of CD4+ TILs positive for CD25 expression correlated with both Class I (P less than 0.05) and Class II (P less than 0.03) expression on the tumour cells while the percentage of CD8+ TILs positive for CD25 did not. The percentage of TILs bearing the transferrin receptor showed no measurable correlation with the expression of either class of MHC antigen on the tumour. The data suggest that MHC expression on the tumour cells has a selective effect on the response capacity of different parts of the immune system.

Dielectric properties of female human breast tissue measured in vitro at 3.2 GHz

Complex permittivities of in vitro diseased and undiseased human female breast tissues have been measured at 3.2 GHz using a resonant cavity technique. Ranges of dielectric properties and water contents of these tissues are presented. Experimental data are compared with models predicted from mixture equations. Measured permittivity data lie within limits set by two-phase mixture theory, but some conductivity data are in excess of those expected for a mixture of saline and protein. At any particular microwave frequency in all tissue of a given type, the relationship between permittivity and conductivity may be parametrized using the Debye relaxation equations. For each breast tissue type a characteristic relaxation frequency was calculated and found to be lower than that of physiological saline at the same temperature. It is concluded that the dielectric relaxation of tissue water is not the only dispersive process occurring at this frequency: dielectric relaxation of bound water and the tail end of a beta-dispersion may also contribute to the dielectric properties. The similarity of the dielectric properties of benign and malignant breast tumours measured in this work suggest that in vivo dielectric imaging methods will not be capable of distinguishing them.

A quick accurate method for measuring the microwave dielectric properties of small tissue samples

A resonant cavity perturbation technique has been developed which provides a quick, simple and accurate method of measuring the microwave dielectric properties of small, easily prepared samples of tissues, tissue-simulating materials and biological fluids. The method gives dielectric properties averaged over the sample volume. The measurement accuracy with the apparatus used is +/- 2.2% for relative permittivity and +/- 3.5% for the loss factor for most tissue and biological material samples. With appropriate basic microwave equipment the method can be applied over the 1.5-6 GHz range of frequencies of interest for active and radiometric tissue microwave imaging.

Nucleotide sequences of avian cardiac and brain SR/ER Ca(2+)-ATPases and functional comparisons with fast twitch Ca(2+)-ATPase. Calcium affinities and inhibitor effects

Two similar forms of the cardiac/slow Ca(2+)-ATPase (SERCA2a and SERCA2b), differing in sodium dodecyl sulfate-polyacrylamide gel electrophoresis mobility, are expressed in chicken heart and brain (Kaprielian, Z., Campbell, A. M., and Fambrough, D. M. (1989) Mol. Brain Res. 6, 55-60). In the current study, cDNAs encoding each form were cloned and sequenced. Chicken SERCA2a is 94% identical to its rabbit homologue, while SERCA2b has an extended carboxyl terminus with 38 of 49 amino acids identical to mammalian homologues. SERCA2b mRNA contains the SERCA2a encoding sequence within its 3'-untranslated region. Chicken genomic DNA sequence reveals that the alternate RNA splicing used to produced SERCA2a and SERCA2b subtypes involves a splice site within an exon. Tissue culture cells expressing the avian SERCA2a, SERCA2b, and SERCA1, each targetting to the endoplasmic reticulum, were used to measure Ca2+ affinities and inhibitor effects; no differences among the three pumps were detected.

Barbourin. A GPIIb-IIIa-specific integrin antagonist from the venom of Sistrurus m. barbouri

Sixty-two snake venoms were screened to identify those which specifically inhibit the adhesive protein binding function of the glycoprotein (GP) IIb-IIIa complex, the receptor-mediating platelet aggregation. Although 52 of these venoms inhibited GPIIb-IIIa, only one of these, from the southeastern pigmy rattlesnake, Sistrurus m. barbouri, was specific for GPIIb-IIIa versus other integrins. The peptide responsible for this activity, termed barbourin, was sequenced and found to be highly homologous to other peptides of the viper venom GPIIb-IIIa antagonist family but was the first member which did not contain the Arg-Gly-Asp (RGD) amino acid sequence, believed to be required for inhibition of receptor function. Instead, barbourin contains the sequence, Lys-Gly-Asp (KGD). The conservative Lys for Arg substitution appears to be the sole structural feature which imparts integrin specificity to barbourin, since venom peptide analogs with Lys substitutions were also specific for GPIIb-IIIa. Thus, barbourin represents a new structural model useful for designing potent and GPIIb-IIIa-specific compounds that may have therapeutic value as platelet aggregation inhibitors.

Structural and secretory characteristics of bovine lung and skin mast cells: evidence for the existence of heterogeneity

We have examined cells dispersed enzymatically from three different sites in the bovine lung (tracheal mucosa, bronchial mucosa and parenchyma) and the skin, in order to ascertain whether the bovine model could be used to study mast cell heterogeneity. Histochemically there were two sub-populations of mast cells present in both lung and skin (on the basis of toluidine blue staining and the sensitivity to formalin fixation), but their proportions were similar in all sites studied. Skin mast cells contained approximately twice the amount of histamine than their counterparts in the lung (P less than 0.05). Functional heterogeneity was examined by in vitro release of histamine following secretagogue challenge. Calcium ionophore induced a substantial release of histamine; skin mast cells releasing significantly more histamine than any of the lung mast cells (at 10 microM ionophore, 37.1% and 20.7% net histamine release, respectively, P less than 0.05), although the time-course of release from the two tissues was similar. The neuropeptides vasoactive intestinal peptide and somatostatin induced a modest but statistically significant release of histamine from both skin and lung mast cells, whilst substance P only induced histamine secretion from skin mast cells. A range of other potential immunological and non-immunological secretagogues was unsuccessful in eliciting histamine release from mast cells in any of the tissues. We conclude that there were no convincing histochemical differences between mast cells from the sites examined in the lung or skin. Additionally, there was no discernable functional heterogeneity between mast cells within the lung, but functional differences were evident between mast cells of the bovine lung and skin. However, in the absence of a suitable immunological stimulus the bovine model cannot be regarded as a good model of mast cell heterogeneity.

The construction of a monoclonal diagnostic system for the field detection of Vibrio cholerae

An enzyme-based double monoclonal field diagnostic system detecting both serotypes of Vibrio cholerae has been developed. The system uses nitrocellulose as a solid support, 1.25% skimmed dried milk as blocking reagent, water as washing reagent, and alkaline phosphatase cross-linked to antibody by means of glutaraldehyde as detecting reagent. The sensitivity of the system was 10(5) vibrios/ml. The biotin-avidin system gave sensitivity an order of magnitude weaker. There were no cross-reactions with the range of other bacteria tested.

Inflammatory processes in asthma

Bronchial inflammation is a characteristic of asthma, but, although postmortem and rare bronchoscopic studies had been performed, it is only after 1980 that many experiments were done. Electron microscopy, immunohistochemistry and molecular biology have enhanced our knowledge. As bronchial biopsies and bronchoalveolar lavage present drawbacks, it is favorable to combine both to obtain the best insights into inflammation. The epithelium is rarely intact in asthmatic patients, the cells being both 'fragile' and activated. Eosinophil inflammation is highly important and likely involved in the damage of the epithelium and submucosa. Airway macrophages and monocytes are present in greater amounts and are activated in the bronchi, and they are certainly involved in the pathogenesis of asthma. Mast cells are activated and some emphasis has been put on lymphocytes. Therefore, asthma appears to be a desquamative bronchitis with mixed cell infiltrate.

Flow cytometric analysis of tumour infiltrating lymphocytes in breast cancer

In 31 patients with carcinoma of the breast the phenotype and activation status of tumour infiltrating lymphocytes (TILs) was analysed by flow cytometry. The predominant cells, in all patients, were T lymphocytes and in the majority of cases CD8+ (cytotoxic/suppressor) T lymphocytes were present in greater numbers than CD4+ (helper) T lymphocytes. There was no relationship between the degree of lymphocytic infiltration and either tumour stage or grade but there appeared to be an inverse correlation with the levels of oestrogen receptor (ER) in the tumour (P less than 0.01). Both populations of T cells had significantly higher numbers of cells carrying HLA DR (class II major histocompatibility antigen) than the equivalent populations in peripheral blood from the same patient group (P less than 0.001). The transferrin receptor was found on similar numbers of CD8+ T cells in peripheral blood and among the tumour infiltrating lymphocytes while more of the CD4+ T cells infiltrating the tumour were found to carry this receptor (P = 0.034). The Tac (CD 25) antigen was also on similar numbers of CD8+ T cells from both peripheral blood and the tumour but was on fewer of the CD4+ T cells in the tumour with respect to peripheral blood (P = 0.029). In both TILs and blood lymphocytes, the Tac antigen was consistently present on greater numbers of CD4+ T lymphocytes than on the CD8+ T lymphocytes (P less than 0.001) and as this is a component of the interleukin 2 (IL-2) receptor this may be of relevance to the use of IL-2 in TIL cancer therapy.

Analysis of lymphocytic infiltration in uveal melanoma

Among 27 uveal melanomas, five were found to contain tumor infiltrating lymphocytes (TILs). Four had high levels of lymphocytes, and the fifth had comparatively low levels but adequate numbers for comprehensive analysis. The TILs were analyzed by flow cytometry to determine the relative proportions of lymphocyte subsets and markers of lymphocyte activation. The results show the predominance of T-suppressor/cytotoxic lymphocytes and insignificant levels of B-cells present in the infiltrate. The T-suppressor/cytotoxic cells were generally activated to a higher degree than the T-helper cells when assayed for levels of the histocompatibility antigen, HLA-DR. T-helper cells expressed more interleukin (IL-2) receptor (Tac) than T-suppressor/cytotoxic cells.

Flow cytometric analysis of cell surface carbohydrates in metastatic human breast cancer

Helix pomatia agglutinin (HPA)- and Concanavalin A (Con A)-binding carbohydrate expression were studied on 32 tumour samples from primary adenocarcinoma of the breast and 12 samples from lymph node metastases. Live cells were spilled from each of the fresh samples and the extent of fluorescent-labelled HPA and Con A-binding was assessed by flow cytometry. The extent of brightness was expressed in a defined quantitative fashion and the percentage of positive cells was accurately determined from a sample of 10,000 cells per tumour. Correlation of binding with clinicopathological features showed that HPA but not Con A related to lymph node involvement (P = 0.001) in tumours of higher grade (II and III). Spilled tumour cells (non-lymphocytes) were selected from the lymph nodes and the presence of HPA binding cells in the involved lymph nodes was found to relate to positive HPA binding in autologous primary tumours (P = 0.002). Dual-label analysis of HPA and Con A binding showed characteristic features for each tumour. The study demonstrates the use of flow cytometry as a simple and effective technique in detecting differences in lectin binding in live spilled cells from fresh breast cancer tissues. This method may prove to be particularly useful if performed preoperatively on cells in fine-needle aspirates.

Evaluation of analytical techniques for measurement of denture-base acrylic resin glass-transition temperature

The glass-transition temperature of a range of acrylic resin materials used in prosthetic dentistry was determined. The techniques used to make the measurement included: thermal mechanical analysis, dynamic mechanical thermal analysis, and differential scanning calorimetry. It was found that the measuring techniques used yielded very similar results, and as a consequence it was concluded that: familiarity and easy availability of thermal mechanical analysis lead to the recommendation that this technique should be employed as the standard glass-transition evaluation technique for denture-base acrylic resins.

Enhancement of leukotriene C4 release from primate airway macrophages by cellular interactions

1. Cells were obtained from the lungs of Macaque monkeys by bronchoalveolar lavage in order to study the role of cellular interactions in the release of leukotriene C4 (LTC4). 2. In normal monkeys, macrophages were the most abundant cell type recovered, whereas in monkeys sensitized with Ascaris suum there was an increase in the numbers of eosinophils and mast cells recovered. 3. Challenge of cells from both groups of animals with an optimal concentration of opsonized zymosan (OPZ) resulted in the time-dependent release of LTC4 from macrophages. However, release was significantly greater in cells obtained from sensitized donors compared to normal donors. 4. Density-gradient centrifugation of cells lavaged from sensitized donors was used to prepare fractions containing both eosinophils and mast cells. Addition of these cells to macrophage populations obtained from non-sensitized donors caused a significant enhancement of OPZ-induced LTC4 release. In the absence of macrophages no significant release of LTC4 was detected from eosinophil/mast cell-containing fractions stimulated with OPZ, despite the fact that the zymosan had been phagocytosed by the eosinophils. 5. There was a significant correlation between the percentage enhancement of LTC4 release and the number of eosinophils added. However, there was not a significant correlation with the number of mast cells added. 6. These results suggest that a cellular interaction between macrophages and eosinophils may be important in the regulation of mediator synthesis and release. The precise mechanism of this effect remains to be elucidated.

Identification of a Ca2+-ATPase in cerebellar Purkinje cells

The expression of a sarcoplasmic reticulum (SR)-like Ca2+-ATPase was studied in the adult chicken cerebellum. A monoclonal antibody. CaS/C1-IgG, specific for the cardiac/slow-twitch skeletal muscle SR Ca2+-ATPase, was used as a probe of protein expression. An immunoblot analysis showed that CaS/C1-IgG recognized similar size polypeptides in adult chicken heart and cerebellum. CaS/C1-IgG recognized fragments of similar size after limited tryptic digestion of cardiac and cerebellar membranes. A two-dimensional alpha-chymotryptic peptide map analysis demonstrated that the cardiac and cerebellar Ca2+-ATPases were structurally very similar. Immunofluorescence microscopy localized the cerebellar Ca2+-ATPase to Purkinje cell bodies and dendritic trees. These results suggest that the well-known Ca2+ uptake system of skeletal and cardiac muscle SR has a remarkably similar counterpart in some neurons.