Intraoperative validation of mitral inflow determination by transesophageal echocardiography: comparison of single-plane, biplane and thermodilution techniques

OBJECTIVES

This study investigated the accuracy of mitral inflow quantification using biplane transesophageal echocardiography.

BACKGROUND

Mitral stroke volume can be reliably quantified by transthoracic Doppler echocardiography, but previous studies involving monoplane transesophageal echocardiography have yielded mixed results.

METHODS

Thirty patients without mitral regurgitation were prospectively examined immediately before cardiovascular surgery. Mitral annulus diameter was measured in the transverse (d1) and longitudinal views (d2) by biplane transesophageal echocardiography. Assuming an elliptic shape, the annular area was calculated as pi d1d2/4; area was also calculated from single-plane data assuming a circular annular shape as pi d2/4. The time-velocity integral of mitral annular Doppler velocity was then multiplied by annular area to yield stroke volume. These data were compared with simultaneous thermodilution measurements by linear regression.

RESULTS

Good correlations were observed between thermodilution (x) and Doppler (y) measurements of stroke volume (SV) (r = 0.86, p < 0.01, delta SV [y-x] = 2.64 +/- 9.86 ml for single four-chamber view; r = 0.77, p < 0.01, delta SV = 1.82 +/- 12.59 ml for two-chamber view; r = 0.94, p < 0.001, delta SV = 1.78 +/- 5.90 ml for biplane measurements) with similar data for cardiac output (r = 0.82, r = 0.74 and r = 0.92, respectively). The biplane measurements were most accurate and had less variability in individual patients (p < 0.05). This finding was supported by a numerical model that demonstrated (for an ellipse of eccentricity 1.5:1) that even maximal misalignment of biplane diameters yielded only 8% area overestimation, whereas single-plane calculations assuming a circular shape produced a variation in area of 225%.

CONCLUSIONS

This study validates the accuracy of measurements of mitral inflow using biplane transesophageal echocardiography with potential application for quantification of valvular regurgitation in the operating room. The results are further generalizable, indicating that orthogonal biplane measurements are both necessary and sufficient to ensure accuracy in area calculation for any elliptic structure.

Selection of patients for transesophageal echocardiography after stroke and systemic embolic events. Role of transthoracic echocardiography

BACKGROUND AND PURPOSE

This study examined whether patients suffering from stroke and other systemic embolic events may be selected for transesophageal echocardiography on the basis of clinical and transthoracic echocardiographic findings.

METHODS

We performed transthoracic and transesophageal echocardiography on 824 patients after stroke and other suspected embolic events. Patients were classified into group A if they were in sinus rhythm and had a normal transthoracic echocardiogram. Group B consisted of all other patients. Transesophageal echocardiographic findings of left atrial spontaneous contrast, left atrial thrombus, complex aortic atheroma, and interatrial septal anomalies were correlated with clinical and transthoracic echocardiographic results.

RESULTS

Transesophageal echocardiography detected at least one potential source of embolism in 399 patients (49%): spontaneous contrast in 214 patients (26%), left atrial thrombus in 54 (7%), complex atheroma in 111 (13%), and interatrial septal anomalies in 126 (15%). In group A (n = 236), only 3 (1%) had spontaneous contrast, 11 (4.6%) had complex atheroma, and none had left atrial thrombus. In group B (n = 588), 211 patients (36%, P < .001) had spontaneous contrast, 54 (9.2%, P < .001) had atrial thrombus, and 100 (17%, P < .001) had complex atheroma. Interatrial septal anomalies were detected in similar proportions of patients (18% in group A versus 14% in group B). Left atrial spontaneous echo contrast, thrombus, and complex atheroma were significantly more prevalent in older patients, but interatrial septal anomalies were more prevalent in younger patients irrespective of transthoracic echocardiographic findings. Multivariate analysis identified both an abnormal transthoracic echocardiogram and patient age to be independent predictors of transesophageal echocardiographic findings of left atrial spontaneous echo contrast, left atrial thrombus, or complex atheroma.

CONCLUSIONS

Transesophageal echocardiography has a low yield for left atrial spontaneous contrast, left atrial thrombus, or complex aortic atheroma in patients with normal transthoracic echocardiogram and sinus rhythm and in younger patients. Interatrial septal anomalies are more prevalent in younger patients. Transthoracic echocardiogram should be performed in patients after stroke or systemic embolic events as a noninvasive screening tool. We recommend transesophageal echocardiogram for patients with abnormal transthoracic echocardiogram and in younger patients when the finding of a patent foramen ovale may contribute to patient management.

Evidence for distinct cytokine expression in allergic versus nonallergic chronic sinusitis

BACKGROUND

The purpose of this study was to characterize the relationship between tissue cytokine expression and the cellular infiltrate present in chronic hyperplastic sinusitis with nasal polyposis (CHS/NP) and to compare the immunopathology and cytokine profile of patients with allergy versus patients without allergy.

METHODS

Nasal polyp tissue samples from 12 patients with CHS/NP and nasal turbinate biopsy specimens from 10 normal control patients were examined for the expression of interleukin (IL)-4, IL-2, and interferon (IFN)-gamma cytokine messenger RNA (mRNA) species by in situ hybridization. These data were analyzed in conjunction with data previously reported for the cytokine mRNA species granulocyte-macrophage colony-stimulating factor (GM-CSF), IL-3, and IL-5 and the immunocytochemical profile of the inflammatory cell infiltrate. Patients with allergy were distinguished from those without allergy on the basis of allergy skin tests.

RESULTS

Tissue eosinophilia was a prominent feature of both allergic and nonallergic CHS/NP and correlated in both subgroups with the density of GM-CSF and IL-3 mRNA+ cells. In comparison with normal controls, patients with allergic CHS/NP had significantly higher CHS/NP had significantly higher tissue densities of GM-CSF, IL-3, IL-4, and IL-5 (p < or = 0.025). In contrast, patients with nonallergic CHS/NP had significantly higher tissue densities of GM-CSF, IL-3, and IFN-gamma (p < or = 0.001). The allergic and nonallergic subgroups showed distinct cytokine profiles with the most distinguishing cytokines of the allergic subgroup being IL-4 (p = 0.001) and IL-5 (p = 0.017) and of the nonallergic subgroup being IFN-gamma (p = 0.004). Furthermore, patients with allergic CHS/NP showed an increased density of CD3+ T lymphocytes compared with either controls or patients with nonallergic CHS/NP (p = 0.03). The density of CD3+ T lymphocytes was the only significant difference between patients with allergic and nonallergic CHS/NP. A clinical history of aspirin sensitivity was strongly correlated with nonallergic CHS/NP, as well as the nonallergic CHS/NP profile of cytokines, including IFN-gamma.

CONCLUSION

We conclude that distinct mechanisms of eosinophilia exist in patients with allergic versus nonallergic CHS/NP. The allergic mechanism involves production of TH2-type cytokines, including GM-CSF, IL-3, IL-4, and IL-5, by infiltrating T lymphocytes. The nonallergic mechanism remains unknown but does involve production of GM-CSF, IL-3, and IFN-gamma. However, nonallergic eosinophilia is independent of IL-4 and IL-5, cytokines that contribute to tissue eosinophilia in allergic inflammation. Aspirin sensitivity is strongly correlated with nonallergic CHS/NP and production of the nonallergic CHS/NP profile of cytokines, including IFN-gamma.

Kawasaki syndrome

Although a general consensus on the etiology of Kawasaki syndrome has not been reached, increasing evidence suggests that this illness represents a response to a superantigen. This conclusion is based on the observations of the immunologic changes that characterize the acute stages of illness as well as on the demonstrated association with toxin-producing bacteria in the pharynx and gastrointestinal tract. Therapy with intravenous gamma globulin and high-dose aspirin remains the standard of care for acute disease. Long-term follow-up of increasing numbers of children has confirmed that few properly treated children are at risk for the development of coronary artery abnormalities due to this illness.

Atopic dermatitis: the skin as a window into the pathogenesis of chronic allergic diseases

This review has attempted to highlight several important advances in our understanding of the immunopathogenesis of AD. These include the observation that IgE has a multifunctional role in the pathogenesis of allergic inflammation. Aside from its involvement in IgE-mediated degranulation of mast cells and basophils, it is also involved in the activation of macrophage/monocytes and the stimulation of TH2 cells. Recent data also suggest that the pattern of cytokine expression in AD depends on the acuity or duration of the skin lesion. The acute onset of skin inflammation in AD is associated with a predominance of T lymphocytes and IL-4 gene expression. In chronic AD, macrophage and eosinophil activation dominate. These effector cells overexpress IL-5, IL-10, GM-CSF, and PGE2, all of which may contribute to the persistence of this disease. Although AD is not simply "asthma of the skin," similar principles may be operative in these associated atopic diseases. Both involve local infiltration of IL-4--and IL-5--secreting TH2-like cells, and both show pathologic evidence of epithelial damage, which likely serves to amplify tissue inflammation. In the case of AD, keratinocyte damage caused by scratching or microbial agents (e.g., S. aureus) is accompanied by the release of proinflammatory cytokines. In the case of asthma, bronchial epithelial damage (e.g., damage caused by viruses or eosinophil cationic proteins) and cytokine release from airway epithelium are believed to play an important role in the pathogenesis of airway inflammation. The observation that chronic AD is associated with lichenification and dermal fibrosis, which are only slowly responsive to topical corticosteroids, is somewhat analogous to the recent concerns over airway remodeling (e.g., subepithelial airway fibrosis) is asthma and the finding that early intervention with inhaled corticosteroids is needed for optimal responses. Differences in the clinical manifestations of disease in these important target organs are likely to lie in their distinct resident cells, environment exposures that occur in the skin but not the lung, and the immune response to allergen sensitization of specialized lymphoid systems. Although the major focus of research in allergy to date has been on understanding of generic mechanisms underlying IgE regulation and action, it is well known that although IgE responses are necessary, they are not sufficient to account for the chronicity or tissue specificity of different allergic diseases.(ABSTRACT TRUNCATED AT 400 WORDS)

Modulation of contact sensitivity responses by bacterial superantigen

Superantigens are potent modulators of the immune system, especially T cells. Therefore, we determined the influence of superantigens on the T-cell-mediated immune response, contact sensitivity. We chose the combination of staphylococcal enterotoxin B (SEB) as superantigen and 2,4-dinitrofluorbenzene (DNFB) as the contact sensitizer, because in BALB/c mice SEB reacts almost exclusively with V beta 8+ T cells, and these cells are capable of transferring contact sensitivity to DNFB from sensitized donors to naive syngeneic recipients. Pretreatment with a single intradermal injection of 50 ng SEB 24 h before DNFB exposure at the same site on the lower abdomen enhanced the induction of contact sensitivity: its intradermal injection permitted sensitization with non-sensitizing concentrations of DNFB as assessed by ear swelling responses after challenge with DNFB. In contrast, pretreatment with repeated intradermal injections of 50 ng SEB every other day over at least 1 week inhibited the induction of contact sensitivity following sensitization. The enhancing effect of SEB may be explained by the creation of a proinflammatory milieu in the skin after a single intradermal injection of the bacterial toxin, whereas the inhibitory effect may be due to tolerization of V beta 8+ T cells. The data indicate that products of skin-colonizing bacteria that can serve as superantigens are able to augment or inhibit the development of contact sensitivity.

The role of superantigens in skin disease

Staphylococcus aureus and streptococci secrete a large family of exotoxins involved in the pathogenesis of toxic-shock-like syndromes and have been implicated in several autoimmune disorders. These toxins act as prototypic superantigens capable of binding to major histocompatibility complex proteins on antigen-presenting cells outside the antigen peptide-binding groove and can thereby stimulate cytokine release from macrophages. The superantigen-major histocompatibility complex unit is recognized primarily by the variable region of the T-cell receptor beta chain, and by engaging this region, can activate a large portion of the T-cell repertoire. It is thought that the capacity of these toxins to cause the massive stimulation of T cells and accessory cells such as macrophages, Langerhans cells, and activated keratinocytes accounts for most of their pathologic effects. The current review examines the evidence that implicates a role for these superantigens in the pathogenesis of certain skin diseases.

Reduced glucocorticoid binding affinity in asthma is related to ongoing allergic inflammation

Recent studies indicate that chronic asthma is associated with a spectrum of glucocorticoid receptor (GCR) binding abnormalities that are cytokine-inducible. These GCR abnormalities may contribute to poor asthma control and failure to respond to glucocorticoid (GC) therapy. The purpose of this study was to determine whether GCR defects are associated with poorly controlled asthma, and whether diminished GCR binding is reversible following a course of GC therapy. We enrolled 12 patients with poorly controlled asthma characterized by nocturnal awakening with cough or wheezing, AM FEV1 < 70%, or FEV1 variability of > 25% requiring a short course of high dose GC therapy. GCR binding affinity was measured in peripheral blood mononuclear cells using a radioligand binding assay before and after the GC course. Spirometry, serum cortisol, eosinophil cationic protein (ECP), and soluble IL-2 receptor (sIL-2R) levels were also performed before and after the GC course. At baseline, all subjects had airflow obstruction that significantly improved (median FEV1 increased from 65.0% to 89.5% of predicted, median FEV1/FVC ratio increased from 0.60 to 0.72) with therapy. A diminished GCR binding affinity at baseline was noted with an elevated median dissociation constant (Kd) of 29.0 nM (interquartile range at the 25th and 75th percentile [IQ] of 22.3 and 44.5 nM) compared with normal controls (Kd 8.0 nM [IQ 7.0, 9.2]). Following the GC course, a significant decrease in the Kd was seen. Serum ECP and sIL-2R levels at baseline were elevated, with serum ECP demonstrating a significant reduction following the GC course.(ABSTRACT TRUNCATED AT 250 WORDS)

Down-regulating effects of IL-4 and IL-10 on the IFN-gamma response in atopic dermatitis

Atopic dermatitis (AD) is a chronic allergic disease associated with toxin (superantigen)-producing Staphylococcus aureus skin infections, impaired delayed hypersensitivity responses, and the expansion of IL-4-secreting Th2 cells, as well as diminished IFN-gamma synthesis. IL-12 is known to induce IFN-gamma synthesis and to augment Th1 responses. In this study, therefore, we examined the potential role of IL-12 in the immunopathogenesis of AD. We show that, after stimulation with staphylococcal toxic shock syndrome toxin-1 (TSST-1) or IL-12, PBMC from patients with AD are deficient in their ability to produce IFN-gamma. PBMC from AD patients, however, produced normal quantities of IL-12 and expressed normal levels of IL-12R. Induction of IFN-gamma by TSST-1 was decreased by neutralizing anti-IL-12 Ab in normal donors, but not in AD patients. The latter observation is consistent with a defective response to IL-12 in AD PBMC. Because AD is associated with increased production of IL-4 and IL-10, we examined the effect of IL-4 on IL-12- or TSST-1-induced IFN-gamma production in normal donors. IL-4 inhibited IL-12-induced IFN-gamma production. Furthermore, Ab neutralization of IL-4 caused increased production of IFN-gamma in AD PBMC. However, neutralization of IL-10 activity caused an even greater augmentation of IFN-gamma production. Our data suggest that despite normal levels of IL-12 production and IL-12R expression, PBMC from AD patients are unable to generate normal IL-12-induced IFN-gamma responses. This defective response may be due to the excess production of IL-4 and IL-10 in this common allergic condition.

Down-regulating effects of IL-4 and IL-10 on the IFN-gamma response in atopic dermatitis

Atopic dermatitis (AD) is a chronic allergic disease associated with toxin (superantigen)-producing Staphylococcus aureus skin infections, impaired delayed hypersensitivity responses, and the expansion of IL-4-secreting Th2 cells, as well as diminished IFN-gamma synthesis. IL-12 is known to induce IFN-gamma synthesis and to augment Th1 responses. In this study, therefore, we examined the potential role of IL-12 in the immunopathogenesis of AD. We show that, after stimulation with staphylococcal toxic shock syndrome toxin-1 (TSST-1) or IL-12, PBMC from patients with AD are deficient in their ability to produce IFN-gamma. PBMC from AD patients, however, produced normal quantities of IL-12 and expressed normal levels of IL-12R. Induction of IFN-gamma by TSST-1 was decreased by neutralizing anti-IL-12 Ab in normal donors, but not in AD patients. The latter observation is consistent with a defective response to IL-12 in AD PBMC. Because AD is associated with increased production of IL-4 and IL-10, we examined the effect of IL-4 on IL-12- or TSST-1-induced IFN-gamma production in normal donors. IL-4 inhibited IL-12-induced IFN-gamma production. Furthermore, Ab neutralization of IL-4 caused increased production of IFN-gamma in AD PBMC. However, neutralization of IL-10 activity caused an even greater augmentation of IFN-gamma production. Our data suggest that despite normal levels of IL-12 production and IL-12R expression, PBMC from AD patients are unable to generate normal IL-12-induced IFN-gamma responses. This defective response may be due to the excess production of IL-4 and IL-10 in this common allergic condition.

Selective expansion of T cells expressing V beta 2 in peanut allergy

Peanuts are the most common cause of fatal and near-fatal food-induced anaphylaxis. The immune basis for susceptibility to peanut allergy is poorly understood. The current study examined the possibility that patients with peanut allergy, as compared to normals, use different T cell receptor variable beta regions (V beta) in the recognition of peanuts. The results demonstrate that stimulation of T cells from patients with peanut allergy results in the selective expansion of V beta 2+ T cells.

Milk-induced eczema is associated with the expansion of T cells expressing cutaneous lymphocyte antigen

The extravasation of T cells at sites of inflammation is critically dependent on the activity of homing receptors (HR) involved in endothelial cell recognition and binding. Two such HR (the cutaneous lymphocyte antigen [CLA] and L-selectin) have been shown to be selectively involved in T cell migration to skin and peripheral lymph nodes, respectively. This study was designed to assess the relationship between the organ specificity of an allergic reaction to food and the expression of HR on T cells activated in vitro by the relevant food allergen. Peripheral blood mononuclear cells were isolated from seven milk allergic children with a history of eczema when exposed to milk. All patients had a positive prick skin test and double-blind placebo-controlled food challenge to milk. 10 children with either allergic eosinophilic gastroenteritis or milk-induced enterocolitis and 8 nonatopic adults served as controls. Five-parameter flow cytometry using monoclonal antibodies was used for detection of the specific HR on freshly isolated T cells versus T cell blasts induced by a 6-d incubation with casein, as compared with Candida albicans. After in vitro stimulation with casein, but not C. albicans, patients with milk allergy and atopic dermatitis had a significantly greater percentage of CLA+ T cells (P < 0.01) than controls with milk-induced enterocolitis, allergic eosinophilic gastroenteritis, or nonatopic healthy controls. In contrast, the percentage of L-selectin-expressing T cells did not differ significantly between these groups. These data suggest that after casein stimulation allergic patients with milk-induced skin disease have an expanded population of CLA+ T cells, as compared with nonatopics or allergic patients without skin involvement. We postulate that heterogeneity in the regulation of HR expression on antigen-specific T cells may play a role in determining sites of involvement in tissue-directed allergic responses.

Bacterial superantigens induce T cell expression of the skin-selective homing receptor, the cutaneous lymphocyte-associated antigen, via stimulation of interleukin 12 production

T lymphocyte infiltration is a prominent feature of the skin inflammation associated with infections by toxin (superantigen)-secreting Staphylococcus aureus or Streptococcus bacteria. The cutaneous lymphocyte-associated antigen (CLA) has been hypothesized to be a homing receptor (HR) involved in selective migration of memory/effector T cells to the skin. Since the expression of this putative skin-selective HR is known to be under strict microenvironmental control, we sought to determine the effect of staphylococcal and streptococcal toxins on T cell expression of CLA. After in vitro stimulation of peripheral blood mononuclear cells with staphylococcal enterotoxin B, toxic shock syndrome toxin-1, and streptococcal pyrogenic exotoxins A and C, there was a significant increase in the numbers of CLA+ T cell blasts (p < 0.01), but not blasts bearing the mucosa-associated adhesion molecule alpha e beta 7-integrin, compared with T cells stimulated with phytohemaglutinin (PHA) or anti-CD3. Bacterial toxins were also found to specifically induce interleukin (IL) 12 production. More importantly, induction of toxin-induced CLA expression was blocked by anti-IL-12, and the addition of IL-12 to PHA-stimulated T cells induced CLA, but not alpha e beta 7-integrin, expression. These data suggest that bacterial toxins induce the expansion of skin-homing CLA+ T cells in an IL-12-dependent manner, and thus may contribute to the development of skin rashes in superantigen-mediated diseases.

Resolution of left atrial spontaneous echocardiographic contrast after percutaneous mitral valvuloplasty: implications for thromboembolic risk

Left atrial spontaneous echocardiographic contrast (SEC) is an important marker of increased thromboembolic risk in patients with mitral stenosis. To evaluate the effect of percutaneous transseptal mitral valvuloplasty (PTMV) on SEC, we performed transesophageal echocardiography 1 day before and 3 months after PTMV on 88 consecutive patients. SEC was present in 65 (74%) patients before PTMV and was associated with absence of moderate or severe mitral regurgitation (p = 0.01), a smaller valve area (p = 0.02), an older age (p = 0.04), and atrial fibrillation (p = 0.05). At 3 months, PTMV resulted in a mean absolute and relative increase in valve area of 0.54 +/- 0.36 cm2 and 53% +/- 43%, respectively. SEC resolved in 37 patients but persisted in 28 (32%) patients at the 3-month study. The absolute and relative increase of valve area and worsened mitral regurgitation after PTMV were predictors of resolution of SEC, with the relative increase in valve area being the only significant predictor on multivariate analysis. PTMV frequently results in resolution of SEC, which may have important implications in reducing the thromboembolic risk in these patients.

Granulocyte macrophage colony-stimulating factor contributes to enhanced monocyte survival in chronic atopic dermatitis

Evidence suggesting that prolonged effector cell survival may contribute to perpetuation of inflammation prompted us to ask whether monocyte macrophages, the predominate inflammatory cell in the lesion of chronic atopic dermatitis (AD), exhibit enhanced survival in AD. Cultures of peripheral blood monocytes from patients with chronic AD, psoriasis, and from normal (NL) donors were examined for morphologic features and DNA fragmentation characteristic of cells undergoing the process of apoptosis (programmed cell death). Cultures of AD monocytes exhibited a significantly lower incidence of apoptosis than did cultures of NL monocytes (45 vs 68%, P < 0.01), or psoriatic monocytes (45 vs 80%, P < 0.01). Furthermore, AD monocytes were unresponsive to both IL-1, an inhibitor of apoptosis, and IL-4, an enhancer of apoptosis, in comparison to cultured NL monocytes. Of note, GM-CSF in a concentration-dependent fashion, decreased the incidence of apoptosis in NL monocyte cultures and rendered them unresponsive to these cytokines. These findings suggested that GM-CSF may enhance monocyte survival in AD. In support of this hypothesis, AD monocyte cultures produced fivefold more GM-CSF than did cultures of NL monocytes or psoriatic monocytes (P < 0.05). Additionally, there was a significantly greater number of GM-CSF mRNA expressing cells detected by in situ hybridization in biopsies of lesions of chronic AD than in acute AD or NL skin (P < 0.05). Finally, NL monocytes incubated with supernatants obtained from monocytes of AD patients exhibited significant inhibition of apoptosis, an effect that could be ablated by a neutralizing antibody to GM-CSF. Taken together, these data strongly suggest that increased production of GM-CSF by cells from patients with AD inhibits monocyte apoptosis and may contribute to the chronicity of this inflammatory disease.

Dysregulation of interleukin 4, interleukin 5, and interferon gamma gene expression in steroid-resistant asthma

In steroid-resistant (SR) asthma, there is a lack of clinical responsiveness to oral prednisone. Previous studies indicate that this may be explained by the effect of the combination of interleukin 2 (IL-2) and IL-4 on glucocorticoid receptor binding affinity. By contrast, steroid-sensitive (SS) asthmatics respond well to glucocorticoids, and this is accompanied by a decrease in the numbers of bronchoalveolar lavage (BAL) messenger RNA+ (mRNA+) cells expressing IL-4 and IL-5, and an increase in interferon gamma (IFN-gamma) transcripts. In the present study, we hypothesized that SR asthma is associated with alterations in T helper types 1/2 (Th2/Th1)-type cytokine gene expression. BAL was performed in six SR asthmatics and six SS asthmatics, before and after a 1-wk course of 40 mg daily prednisone. mRNA+ cells for IL-2, IL-4, IL-5, and IFN-gamma was measured by in situ hybridization using 35S-labeled RNA probes. Before prednisone therapy, there were significantly greater numbers of BAL cells (per 1,000) expressing IL-2 mRNA (p < 0.01) and IL-4 mRNA (p < 0.05) in SR asthmatics as compared with SS asthmatics, but no differences between the two groups in the numbers of BAL cells expressing IFN-gamma or IL-5 mRNA expression were observed. After a 1-wk course of prednisone, IL-2 expression was not altered in either group. However, SS asthmatics had a significant decrease in the numbers of BAL cells expressing mRNA for IL-4 (p < 0.01) and IL-5 (p < 0.001), and a rise in the numbers of IFN-gamma mRNA+ cells (p < 0.01). In contrast, after prednisone treatment, SR asthmatics had no significant change in either the number of BAL cells expressing mRNA for IL-4 or IL-5. Of note, there was an unexpected decrease in the numbers of IFN-gamma mRNA+ cells (p = 0.05). Our current findings indicate that SR asthma is associated with a dysregulation of the expression of the genes encoding for Th2/Th1 cytokines in airway cells and is compatible with the concept that a combination of IL-2 and IL-4 induce glucocorticoid (GR) binding affinity and T cell responsiveness to glucocorticoids.

Inhibition of the development of immediate hypersensitivity by staphylococcal enterotoxin B

We investigated the ability of staphylococcal enterotoxin B (SEB) to modify the immediate hypersensitivity response induced in BALB/c mice following sensitization to ovalbumin (OVA), a response mediated by OVA-reactive V beta 8 T cells. Mice were sensitized by skin painting with OVA every second day over a period of 2 weeks. SEB, a potent activator of V beta 8+ T cells, was administered at the same site where OVA was applied (skin of the lower abdomen) following two different protocols. In protocol (A) SEB was injected intradermally 1 day before painting with OVA and on day 7; in protocol B, SEB was injected each time OVA was applied to the skin (eight times). SEB (but not SEA) altered the development of immediate hypersensitivity to OVA, as demonstrated by the reduction in allergen-specific IgE, decreased OVA-specific immediate skin test responsiveness, and prevented the development of increased airways responsiveness after bronchial challenge with OVA. Injections of SEB did not alter the proliferative responses of local draining lymph node cells or spleen mononuclear cells to OVA, indicating that administration of SEB did not inhibit the sensitization of OVA, but shifted the immune response away from an immediate type response (IgE/IgG1) to IgG2a, IgG2b and IgG3. Although both protocols of SEB treatment did not lead to a major deletion of the V beta 8 T cell population, they did reduce the proliferative response of V beta 8+ T cells to OVA. These data indicate that the bacterial toxin SEB is capable of modifying the immediate hypersensitivity response induced by OVA by altering the functional capacity of antigen-reactive V beta 8 T cells.

Legionella and Pneumocystis pneumonias in asthmatic children on high doses of systemic steroids

Asthma is increasingly treated as an inflammatory disease with inhaled and/or systemic corticosteroids. We report 3 cases of unusual pneumonias associated with high doses of oral steroids. Two patients contracted Legionella pneumonia and one patient contracted Pneumocystis carinii pneumonia. With increasing usage, it is important for physicians to be aware of the possible infectious complications of high dose steroids. This report highlights the risk of corticosteroid treatment in asthma in predisposing to opportunistic infections that have not heretofore been readily associated with asthma.

Prognostic implications of left atrial spontaneous echo contrast in nonvalvular atrial fibrillation

OBJECTIVES

This study examined the influence of left atrial spontaneous echo contrast on the subsequent stroke or embolic event rate and on survival in patients with nonvalvular atrial fibrillation.

BACKGROUND

Left atrial spontaneous echo contrast is associated with atrial fibrillation and a history of previous stroke or other embolic events. However, the prognostic implications of spontaneous contrast in patients with nonvalvular atrial fibrillation are unknown.

METHOD

The study group comprised 272 consecutive patients with nonvalvular atrial fibrillation undergoing transesophageal echocardiography. Clinical and echocardiographic data were collected at baseline, and patients were prospectively followed up, and all strokes, other embolic events and deaths were documented. The relation between spontaneous contrast at baseline and subsequent stroke, other embolic events and survival was analyzed.

RESULTS

Left atrial spontaneous echo contrast was detected at baseline in 161 patients (59%). The mean follow-up was 17.5 months. The stroke or other embolic event rate was 12%/year (15 strokes, 3 transient ischemic attacks, 2 peripheral embolisms) in patients with, compared with 3%/year (5 strokes) in patients without, baseline spontaneous contrast (p = 0.002). In 149 patients without previous thromboembolism, the event rate was 9.5%/year in patients with and 2.2%/year in patients without spontaneous contrast (p = 0.003). There were 25 deaths in patients with and 11 deaths in patients without spontaneous contrast. Patients with spontaneous contrast had significantly reduced survival (p = 0.025). On multivariate analysis, spontaneous contrast was the only positive predictor (odds ratio 3.5, p = 0.03) and warfarin therapy on follow-up the only negative predictor (odds ratio 0.23, p = 0.02) of subsequent stroke or other embolic events.

CONCLUSIONS

Transesophageal echocardiography can risk stratify patients with nonvalvular atrial fibrillation by identifying left atrial spontaneous echo contrast. These patients have both a significantly higher risk of developing stroke or other embolic events and a reduced survival, and they may represent a subgroup in whom the risk/benefit ratio of anticoagulation may be most favorable.

In vivo effects of glucocorticoids on IgE production

Recent in vitro investigations have demonstrated that corticosteroids in combination with interleukin-4 induce the synthesis of IgE. Corticosteroids are increasingly being used to treat the inflammatory component of asthma. This has raised concern over the potential in vivo effects of corticosteroids on IgE production and the correlation of IgE-enhancing effects with clinical effects on asthma. In this study 10 patients with asthma were given a 7-day course of 20 mg of prednisone, administered orally two times a day. All of the patients had a rise in serum IgE levels after the course of prednisone (p = 0.005). Detection of specific IgE to pollen and perennial allergens demonstrated that the rise in serum IgE was polyclonal. Peripheral blood mononuclear cells from patients treated with prednisone produced increased levels of IgE in vitro when exogenous IL-4 was added to their cultures. Peripheral blood mononuclear cells obtained from patients before and after administration of prednisone revealed a significant decrease in interferon-gamma synthesis (p = 0.005), but not in interleukin-4 (p = 0.6), after the course of prednisone. These findings were paralleled by a significant decrease in the frequency of interferon-gamma (p = 0.03), but not interleukin-4 (p = 1.0) expressing cells. Despite the increase in IgE synthesis, there was a significant increase in forced expiratory volume in 1 second after the course of prednisone (p = 0.01). These data suggest that the observed rise in IgE production associated with prednisone treatment is not clinically deleterious but reflects the immunomodulatory effects of corticosteroids on T lymphocytes.