Glucocorticoid-induced growth inhibition of human neoplastic salivary gland duct cell line (HSG)

The purpose of this study was to examine the effect of glucocorticoid on human neoplastic salivary duct epithelial cell line (HSG). Dexamethasone was found to inhibit cell growth and to increase cell size and the ratio of protein content to DNA content in a cell. The inhibition of cell growth was dose-dependent; in comparison to the control (33.8 +/- 3.1 h), the population doubling time was 1.57-fold longer in 10(-5) M dexamethasone (P less than 0.01, N-K test). [3H] thymidine incorporation was inhibited in 45.5% of the control at 10(-5) M. Plating efficiency was 20.5 +/- 3.0% in 10(-5) M and 47.0 +/- 4.4% in the absence of dexamethasone. Cell diameters increased 1.29 fold in 10(-5) M dexamethasone in comparison to the control size (16.0 +/- 2.1 micron). The ratio of total protein content of DNA content increased 1.46 fold in 10(-5) M dexamethasone-treated cells on the seventh day of cultivation. Scatchard plot analysis using [6, 7-3H]-triamcinolone revealed that the HSG cells had apparent cytosolic glucocorticoid receptors with an equilibrium dissociation constant (Kd value) of 6.48 nM, whose number of binding sites (NBS) was 57.8 fmol/mg protein.     

Effects of lipoxin A4 on chemotaxis and degranulation of human eosinophils stimulated by platelet-activating factor and N-formyl-L-methionyl-L-leucyl-L-phenylalanine

Lipoxins are trihydroxytetraene metabolites derived through a double lipoxygenation of arachidonic acid. Lipoxin A₄ (LXA₄) was prepared by total chemical synthesis, and its capacity to modulate eosinophil migration has been evaluated. LXA₄ is a weak and partial chemotactic agent; at 10⁻⁶ M, it achieved about 20% of the response of 10⁻⁶ M platelet-activating factor (PAF). Preincubation of eosinophils with increasing doses of LXA₄ (10⁻¹⁰−10⁻⁵ M) resulted in a concentration-dependent inhibition of cell migration induced by 10^-6 M formyl-methionyl-leucyl-phenylalanine (FMLP) and 10^-6 M PAF. The concentration of LXA₄ which produced 50% inhibition (IC₅₀) of eosinophil migration was approximately 10^-6 M. LXA₄ (10^-10-10^-6 M) did not elicit ECP release or modulate ECP release induced by 10^-6 M FMLP. LXA₄ may have antiallergic properties in preventing eosinophilic migration.     

Determination of in vitro postantibiotic effects in Staphylococcus aureus and Escherichia coli by [3H]thymidine incorporation

Postantibiotic effects (PAE) and control-related effective regrowth time (CERT) of dicloxacillin, vancomycin, rifampin and gentamicin in Staphylococcus aureus and imipenem, gentamicin, tobramycin, doxycycline and rifampin in Escherichia coli were measured by standard viability counting and [³H]thymidine incorporation. For PAE determination, the two methods correlated well; r ² = 0.821 for S. aureus and r ² = 0.939 for E. coli . For viable counts below the detection limits of 10⁵ to 10⁶ log₁₀ CFU/mL, the PAE was overestimated by the [³H]thymidine method. Quantitation of CERT by both methods showed a good correlation, r ² = 0.867 for S. aureus and r ² = 0.997 for E. coli . Measuring [³H]thymidine incorporation in bacteria is a novel alternative method for the determination of PAE and CERT.     

Methacholine induces wheal-and-flare reactions in human skin but does not release histamine in vivo as assessed by the skin microdialysis technique

A number of investigations have indicated that cholinergic agonists release histamine from isolated mast cells and suggested that cholinergic stimulation releases histamine in vivo. The purpose of this study was to investigate whether the cutaneous wheal-and-flare reaction induced by methacholine challenge in human skin involves histamine release as measured by the skin microdialysis technique. Five hollow dialysis fibers were inserted intradermally in forearm skin in eight healthy subjects. Each fiber was perfused with Kreb's-Ringer bicarbonate at a rate of 3 μl/min. Dialysates were collected in 2-min fractions before skin challenge and for 20 min after intradermal injection of methacholine 10–^-3 -10^-1 M, the vehicle, and a positive control, codeine phosphate 0.3 mg/ml. Histamine was assayed spectrofluorometrically. Methacholine caused a statistically significant dose-related wheal-and-flare reaction, the flare reaction to methacholine 10^-1 M being comparable with that seen with codeine 0.3 mg/ml. No significant histamine release was observed with methacholine, cumulative histamine release of 16 ± 8nM by methacholine 10^-1 M being similar to vehicle responses of 15 ± 9 nM. Histamine release by codeine was 2524 ± 435 nM. In conclusion, methacholine-induced wheal-and-flare reactions in human skin appeared not to involve histamine release from skin mast cells.     

Increased Number of IgG Fc Receptors on Monocyte-Enriched Peripheral Blood Leucocytes from Patients with Rheumatoid Arthritis

The number of free Fc receptors (FcR) per cell and the association constant (K_ass) for the binding of monomeric IgG were determined for monocyte-enriched peripheral blood mononuclear cells, isolated from 16 patients with active classical rheumatoid arthritis (RA) and from 15 normal healthy donors. The assay system was based on binding under equili brium conditions of ¹²⁵I-labelled monomeric rabbit IgG to monocytes purified from peripheral blood on a continuous gradient of Petcoll. Monocytes from 14 untreated RA patients (6 seropositive, 8 seronegative) expressed on the average 4.8±1.3 × 10⁴ FcR/cell. This number was significantly higher (P<0.01) than that found in the control group (3.46±0.7 × 10⁴ FcR/cell). There was also a significant difference between the mean K _ass of the RA group and the control group-2.1±0.7 × 10³1/mol and 2.6±1.0 × 10³ 1/mol, respectively (0.05 >P> 0.01). Two seropositive RA patients receiving systemic treatment with penicillamine expressed the same number of FcR/cell as the mean of the control group (3.6 ± 10⁴). Levels of circulating immune complexes (CIC) and of the complement-factor C3 split product C3d were also measured. No correlation was found between the number of FcR/cell and the concentration of C3d, but there was a weak correlation between the number of FcR/ccll and the level of CIC.     

Decreased peripheral blood γδ T cells in patients with bronchial asthma

Many cell populations are thought to be involved in the etiopathogenesis of bronchial asthma. We examined by flow cytometry the relative and absolute number of CD3*, CD4*, CD8*γδ TcR* T cells. CD19* B cells; and CD56* natural killer (NK) cells in the peripheral blood of 26 adult patients with difficult-to-control asthma (DCA) and 22 patients with minimally symptomatic asthma (MSA). Statistically higher relative and absolute numbers of NK cells (18.39±10.67% and 0.38±0.17×10⁹/l) in comparison with healthy controls (ll.77±8.06% and 0.25±0.19×10⁹/l) and significantly decreased relative and absolute numbers of γδ T cells (3.02±2.16% and 0.06±0.04×10⁹/l) in comparison with controls (5.65+2.90% and 0.13±0.08×10⁹/l) in the DCA patient group were found. After pooling of data from both MSA and DCA patients and dividing the patients according to the presence of allergy, the relative and absolute numbers of 78 T celts were found to be diminished in both the allergy (3.77±2.98 and O.O7±0.O5 ×10⁹/l) and nonallergy (3.06±1.78% and 0.06±0.03 ×10⁹/l) groups in comparison with healthy controls. The reason for the low number of 78 T cells in the peripheral blood of patients suffering from bronchial asthma is under investigation.     

Kinetic Analysis of Subset Growth and B-Cell Activation in Pokeweed Mitogen-Stimulated Cultures of Peripheral Blood Mononuclear Cells Depleted of or Enriched for OKT8+ Cells

Peripheral blood mononuclcar cells (PBMN) that were depleted of OKT8⁺ cells and stimulated with pokeweed mitogen (PWM) produced higher cell yields and higher numbers of plaque-forming cells than unfractionated PBMN. Conversely, OKT8-enriched PBMN, prepared by mixing unfractionated and OKT8⁺ cells in a ratio of 3:1, gave reduced cell growth and B-cell activation. In OKT8-depleted cultures, B cells, OKT4⁺ cells, OKT8⁺ cells, and OKM1⁺ cells increased in number between days 4 and 7 of culture by factors of 9.8, 5.9, 20.1, and 5.6 respectively, whereas growth rates for these subsets were 2.4, 1.0, 2.0, and 1.3 in unfractionated cultures and 0.9, 1.0, 1.2, and 0.6 in cultures enriched for OKT8⁺ cells. On day 7 of culture, 73±10% of B cells secreted immunoglobulin in unfractionated cultures, whereas only 21±10% of B cells were activated in OKT8-enriched cultures. Surprisingly, PWM stimulation of OKT8-depleted PBMN produced only 40±12% activated B cells.     

Hypoxic preconditioning enhances renal superoxide dismutase levels in rats

Renal ischaemia releases reactive oxygen species (ROS) in the kidneys. We hypothesized that the kidneys are more resistant to the insult of ROS in chronically hypoxic rats. We thus compared rats kept at sea level (SL) and those that had been adapted to hypoxia (hypoxia adapted, HA) by exposure to an altitude of 5500 m in an altitude chamber for 15 h day⁻¹ for 4 weeks. Xanthine (X, 0.75 mg kg⁻¹) and xanthine oxidase (XO, 24.8 mU kg⁻¹) were injected intrarenally. A lucigenin-enhanced chemiluminescence method was employed to detect the amount of free radicals in renal venous blood samples and on the kidney surface. In the renal venous blood samples, 26.05 (± 4.36) × 10⁴ and 10.98 (± 1.79) × 10⁴ counts were detected in the SL and HA rats, respectively, after X-XO treatment; these figures were significantly different. On the kidney surface of the SL rats, the free radical count amounted to 12.77 (± 1.64) × 10⁴, while that in the HA rats was 8.47 (± 0.42) × 10⁴; these figures were also significantly different. There was a significant increase in urine volume and urinary excretion of Na⁺, K⁺ and protein after X-XO administration in both groups of rats. However, the effect was greater for the SL rats than for the HA rats. The lipid peroxidation of the kidneys was not significantly different in the two groups of rats. Finally, we found that the activity of superoxide dismutase (SOD) and SOD mRNA were higher in the renal tissue of HA rats. We conclude that the renal response to free radicals is attenuated after chronic hypoxia in rats, and that SOD might play an important role in protecting HA rats from oxidative stress.     

High throughput protein expression screening in the nervous system – needs and limitations

The cellular complexity of the brain (some estimate that there are up to 10³ different cell types) is exceeded by the synaptic complexity, with each of the ∼10¹¹ neurons in the brain having around 10³–10⁴ synapses. Proteomic studies of the synapse have revealed that the postsynaptic density is the most complex multiprotein structure yet identified, with ∼10³ different proteins. Such studies, however, use brain tissue with many different regions and therefore different cell types, and there is clear potential for heterogeneity of protein content at different synapses within and between brain regions. Although large-scale mRNA-based assays are in progress to map this sort of complexity at the cellular level, and indeed all brain-expressed genes, analysis of protein distribution (at synapses and other structures) is still in the very early stages. We review existing large-scale protein expression studies and the specific technical obstacles that need to be overcome before applying the scaling used in nucleic acid based approaches.     

Binding Affinity of Human Autoantibodies: Studies of Cryoglobulin IgM Rheumatoid Factors and IgG Autoantibodies to Albumin

The binding affinity of cryoglobulin IgM rheumatoid factors (RF) for human IgG and of human IgG anti-albumin autoantibodies for HSA was measured by the molecular sieving technique. The binding affinities of the two autoantibodies were consistently low (10⁴-10⁵ I/M) as compared to the affinities of corresponding hyperimmune animal antibodies (10⁶-10⁸ I/M). The findings were discussed in relation to theories on human autoimmunity. The existence of strict autotolerance at the T cell level and of autoreactivity at the low affinity B cell level was considered to be best compatible with the findings of this study and with the major known facts of autoimmunity.     

Receptor for α1-Microglobulin on T Lymphocytes: Inhibition of Antigen-Induced Interleukin-2 Production

The human plasma protein α₁-microglobulin (α₁m) was found to inhibit the antigen-induced interleukin-2 (IL-2) production of two different mouse T-helper cell hybridomas. α₁m isolated from human plasma and recombinant α₁m isolated from baculovirus-infected insect cell cultures had similar inhibitory effects. Flow cytometric analysis showed a binding of plasma and recombinant α₁m to the T-cell hybridomas as well as to a human T-cell line. Radiolabelled plasma and recombinant α₁m bound to the T-cell hybridomas in a saturable manner and the binding could be eliminated by trypsination of the cells. The affinity constants for the cell binding were calculated to be 0.4–1 × 10⁵  M ⁻¹ using Scatchard plotting, and the number of binding sites per cell was estimated to be 5 × 10⁵–1 × 10⁶. The cell-surface proteins of one of the T-cell hybridomas were radiolabelled, the cells lysed and α₁m-binding proteins isolated by affinity chromatography. SDS–PAGE and autoradiography analysis of the eluate revealed major bands with M _r-values around 70, 35 and 15 kDa. The results thus suggest that α₁m binds to a specific receptor on T cells and that the binding leads to inhibition of antigen-stimulated IL-2 production by T-helper cells.     

Effect of dexamethasone on skeletal muscle Na+,K+ pump subunit specific expression and K+ homeostasis during exercise in humans

The effect of dexamethasone on Na⁺,K⁺ pump subunit expression and muscle exchange of K⁺ during exercise in humans was investigated. Nine healthy male subjects completed a randomized double blind placebo controlled protocol, with ingestion of dexamethasone (Dex: 2 × 2 mg per day) or placebo (Pla) for 5 days. Na⁺,K⁺ pump catalytic α1 and α2 subunit expression was ∼17% higher ( P < 0.05) and the structural β1 and β2 subunit expression was ∼6–8% higher ( P < 0.05) after Dex compared with Pla. During one-legged knee-extension for 10 min at low intensity (LI; 18.6 ± 1.0 W), two moderate intensity (51.7 ± 2.4 W) exercise bouts (MI₁: 5 min; 2 min recovery; MI₂: exhaustive) and two high-intensity (71.7 ± 2.5 W) exercise bouts (HI₁: 1 min 40 s; 2 min recovery; HI₂: exhaustive), femoral venous K⁺ was lower ( P < 0.05) in Dex compared with Pla. Thigh K⁺ release was lower ( P < 0.05) in Dex compared with Pla in LI and MI, but not in HI. Time to exhaustion in MI₂ tended to improve (393 ± 50 s versus 294 ± 41 s; P = 0.07) in Dex compared with Pla, whereas no difference was detected in HI₂ (106 ± 10 s versus 108 ± 9 s). The results indicate that an increased Na⁺,K⁺ pump expression per se is of importance for thigh K⁺ reuptake at the onset of low and moderate intensity exercise, but less important during high intensity exercise.     

The Role of the Different CD34 Epitopes in Detection and Positive Selection of CD34+ Bone Marrow and Peripheral Blood Stem Cells

Positive selection of CD34⁺ cells is an attractive approach to reduce tumour cell contamination in bone marrow (BM) and peripheral blood progenitor cell (PBPC) autografts in malignancies not expressing CD34. All current selection methods use monoclonal antibodies (MoAbs) specific for the class I or class II CD34 epitopes, while for detection most investigators use class III MoAbs. Since the distribution of the different CD34 epitopes on haematopoietic progenitors differs, we studied their significance in CD34⁺ selection procedures. Testing MoAbs against class I, II and III CD34 epitopes on normal BM we observed that ± 23% of class III positive cells was class I negative. A higher expression of the class III epitope compared with classes I or II was observed on the KG1 cell line, whereas no differences in binding capability were found. The class III epitope anti-CD34, 561, was compared with the class I epitope anti-CD34, BI-3C5, both coupled to M450 Dynabeads. The yield of CD34⁺ cells obtained with the 561 beads was 1.7% of the mononuclear cells versus 0.95% using the class I epitope, a 1.95-fold increase (1.3–2.7), whereas the purity was similar (96% in both cases). The absolute number of CD34⁺ cells was therefore twofold higher after 561 selection, including cells with a more mature phenotype. In single cell assay comparable numbers of highly proliferative progenitors but higher numbers of differentiated colonies per phenotypic subfraction were measured. In conclusion, M450 beads coated with the 561 anti-class III CD34 epitope are more efficient in isolating CD34⁺ cells from bone marrow, probably due to a broader distribution of the class III epitope.     

Mitogenic Activation of Human Lymphocytes: a Protein A Plaque Assay Evaluation of Polyclonal B-Cell Activators

Using the protein A plaque assay, the capacity of various polyclonal B cell activators to induce differentiation in human B lymphocytes was investigated. Dextran sulphate and native Dextran were both virtually devoid of mitogenic properties, Lipopolysaccharide, however, was round to be a potent mitogen in human cells that, although giving rise to low DNA synthetic response, induced high numbers of immunoglobulin-synthesizing cells. Mean plaque-forming cell (PFC) numbers in healthy blood donors assayed on the optimal day (days 5–7) were 23, 493 IgM/10⁴ cells, 11, 288 IgG/10⁶ cells, and 2643 IgA/10⁶ cells. Values obtained in spleen cells, peaking at days 4–6, were slightly higher. Purified protein derivative (PPD) was equally or oven more-effective than lipopolysaccharide (LPS) in generating PFC of different subclasses in peripheral blood with mean of 29, 241 IgM/10⁶, 21, 269 IgG/10⁶, and 3681 IgA/10⁶. PPD furthermore induced a marked DNA synthetic response in human lymphocytes. These data suggest that LPS and PPD may both be used as functional markers in human cells when analysing patients with a suspected immunodeficiency state. It is suggested that cultures should be assayed using the protein A plaque assay, thereby being able not only to investigate the individual immunoglobulin classes but also to avoid the possible hazards involved in measuring antigen-specific responses in patients whose prior immunization to the antigen tested can never be totally excluded     

Effects of gastrin on the histamine-secretory and proliferative activity of cultured carcinoid cells derived from the stomach of the rodent Mastomys natalensis

The effects of gastrin on the synthesis and release of hista-mine and on cellular prollferatlon were Investigated in a homotransplantable carcinold tumor implanted in the rodent Mastomys natalensis and in cultured cells derived from the tumor. The homotransplanted tumor was immunopositive for histamine, synaptophysin and protein gene product 9.5, and its cells contained numerous secretory granules that were vlsualized by electron microscopy. When carcinold cells were cultured in a medlum with a high concentration of gastrin-1 (10⁴ pg/mL) for 7 days, large electron-dense secretory granules were characteristically observed in the cytoplasm. By contrast, only a few such granules and numerous seaondary lysosomes were seen in cells that had been cultured in the same medium without gastrin-1. A high concentration of gastrin-1 (10⁴ pg/mL) slgniflcantly Increased the release of histamine Into the culture medium from the carcinoid cells compared wlth the control (P<0.05). Cellular proIiferation, as determlned by monitoring the incorporatlon of [methyl-³H]-thymidine into the carcinold cells Increased sig nfficantly at lower concentrations of gastrin-1 (10² and 10³ pg/ mL), (P<0.05). At higher concentratlons (10⁴ pg/mL or more), gastrin-1 had no effect on proliferatlon. These findings Indicate that gastrin stimulates the synthesis and release of histamlne by carclnoid cells, as well as their proliferation.     

Kinetics of the Reaction between a Monoclonal IgM Anti-I and Rabbit Red Cells

Rabbit red cells were found to bind a maximum of 1.8 × 10⁵ IgM anti-I-molecules. A K-value of 5.0 ± 0.8 × 10⁸ 1/M was determined for the reaction between the cells and intact anti-I at 5°C; the K-value was little affected by changes in temperature. Hybrid 17S and 8S molecules composed of varying amounts of cold agglutinin and inactive IgM were prepared by reduction with 2-mercaptoethanol and reassociation. The results obtained with the reassociated products indicate random reassociation at the half subunit level. It is concluded that a 17S fraction with four or more active half subunits shows binding similar to intact IgM, while 8S fractions with two active half subunits show binding similar to the cysteine-reduced 8S IgM.     

Complement (C3) Conversion by Rat Intestinal Glycoprotein and its Degradation Products

Several fragments obtained from alkaline borohydride degradation of a rat intestinal glycoprotein fraction have been tested for anti-complementary activity. Oligosaccharide alditols with a molecular weight of les than about 1 ± 10³ daltons showed no activity, whereas reduced oligosaccharides in the molecular weight range of about 1 ± 10³ to 3 ± 10³ daltons exerted a minor conversion of C3 by the alternative pathway. The low molecular weight fragments tested did not influence C3 conversion induced by the intact intestinal glycoprotein fraction. Of the fragments a peptide fraction, with an 'avenge' molecular weight of 2 ± 10³ daltons, and peptide-containing glycoconjugates exerted activation of C3 by both th classical and alternative pathways. Classical pathway activation by the intestinal glycoproteins depended on antibody, whereas alternative pathway activation did not. Alternative pathway activation appeared to require Factor B in that the intestinal glycoprotein induced no C3 conversion in serum heated to 50°C for 20 min. The rat intestinal glycoproteins had no protease activity on casein and no stimulating effect on human lymphocytes in vitro. Branching of oligosaccharide chains was not indicated by the methylation analyses carried out.     

Evidence of porcine and human endothelium activation by cancer-associated carbohydrates expressed on glycoproteins and tumour cells

It is well established that after metastatic cancer cells escape the primary tumour and enter the circulation, their interactions with microvascular endothelium of a target organ constitute an essential rate-limiting step in haematogenous cancer metastasis. However, the physiological and biochemical processes supporting neoplastic cell arrest and retention in the microcirculation are still poorly understood. In this study, we present experimental evidence that microvascular endothelium of metastasis-prone tissues undergoes activation in response to desialylated cancer-associated carbohydrate structures such as Thomsen–Friedenreich (TF) antigen (Galβ1–3GalNAc) expressed on circulating glycoproteins and neoplastic cells. The metastasis-associated endothelium activation, manifested by marked increase in endothelial cell surface galectin-3 expression, causes gradual decrease in cancer cell velocities (from 72 × 10²± 33 × 10²μm s⁻¹ to 7.6 × 10²± 1.9 × 10²μm s⁻¹, mean ± s.d. ) accompanied by a corresponding increase in the percentage of rolling cells (from 3.3%± 1.2% to 24.3%± 3.6%, mean ± s.d. ), and results in human breast and prostate carcinoma cell arrest and retention in the microvasculature. This process, which could be of high importance in haematogenous cancer metastasis, was inhibited efficiently by an anti-TF antigen function-blocking antibody. Carbohydrate-mediated endothelial activation could be a process of physiological significance as it probably occurs in the interactions between a variety of circulating constituents and the vessel wall.     

Specific Interferon-Gamma Producing CD4+ and CD8+ T Cells After Autologous EBV-B Stimulation: The Necessity of Restimulation

The response of T cells to produce interferon-γ, to proliferate and to become cytotoxic after specific stimulation with low dose (2%) autologous EBV-B cells was investigated in 15 EBV seropositive and five seronegative patients. A significantly higher number of interferon-γ producing cells (56 ± 24 per 10⁵ T cells) were found in a spot ELISA in EBV positive than in EBV negative patients (7 ± 2 spots, P<0.01) and it was only found with restimulation after 5–12 days of primary culture. No correlation was found between the extent of interferon-γ production, cytotoxicity or profileration. Specificity of EBV-induced interferon-γ production was demonstrated by comparison of the response to allogeneic EBV-B cells or IL-2 in the reslimulation phase. The response was stronger in CDS⁺ T cells than in CD4⁺ T cells and could be blocked in the restimulation phase with HLA class I and class II antiserum, respectively.     

γδ intraepithelial lymphocytes drive tumor necrosis factor-α responsiveness to intestinal iron challenge: relevance to hemochromatosis

Summary: The dependence of intestinal epithelial cell (IEC) growth and differentiation on intraepithelial lymphocytes (IELs) expressing the gamma/delta (γδ) T-cell receptor (TCR), suggested a potential role for γδ⁺ IELs in the regulation of iron absorption. We therefore examined the levels of hepatic iron and the IEL cytokine responses in C57BL/6J control and class I and TCR knockout lines (placed on a C57BL/6J genetic background) following the administration of supplemental dietary iron. The highest level of liver iron was found in the β2-microglobulin knockout (β2m^-/-) mice followed by the TCR-δ knockout (TCRδ^-/-) animals. TCR-α knockout (TCRα^-/-) and control animals did not differ in their iron levels. Liver iron loading correlated inversely with rhe ability of the mice to generate an IEL tumor necrosis factor (TNE)-α response. These observations suggest a model in which IEC iron loading is communicated to IELs via the HFE class I protein. The result of this communication is the initiation of TNE-α release by γδ⁺ IELs (sustained by macrophages and dendritic cells) contributing to the upregulation of ferritin expression and possibly to the normal maintenance of the IEC apoptotic pathway.