Prenatal diagnosis and planned peripartum care improve perinatal outcome of fetuses with transposition of the great arteries and intact ventricular septum in low-resource settings

OBJECTIVE

To report on the feasibility of establishing a regional prenatal referral network for critical congenital heart defects (CHDs) and its impact on perinatal outcome of fetuses with transposition of the great arteries and intact ventricular septum (TGA-IVS) in low-resource settings.

METHODS

This was a retrospective study of consecutive fetuses with a diagnosis of TGA-IVS between January 2011 and December 2019 in Kochi, Kerala, India. A regional network for prenatal diagnosis and referral of patients with critical CHDs was initiated in 2011. Pregnancy and early neonatal outcomes were reported. The impact of the timing of diagnosis (prenatal or after birth) on age at surgery, perinatal mortality and postoperative recovery was evaluated.

RESULTS

A total of 82 fetuses with TGA-IVS were included. Diagnosis typically occurred later on in gestation, at a median of 25 (interquartile range (IQR), 21-32) weeks. The majority (78.0%) of affected pregnancies resulted in live birth, most (84.4%) of which occurred in a specialist pediatric cardiac centers. Delivery in a specialist center, compared with delivery in a local maternity center, was associated with a significantly higher rate of surgical correction (98.1% vs 70.0%; P = 0.01) and overall lower neonatal mortality (3.7% vs 50%; P = 0.001). The proportion of cases undergoing arterial switch operation after prenatal diagnosis of TGA-IVS increased significantly, along with the prenatal detection rate, over the study period (2011-2015, 11.1% vs 2016-2019, 29.4%; P = 0.001). Median age at surgery was significantly lower in the prenatally diagnosed group than that in the postnatally diagnosed group (4 days (IQR, 1-23 days) vs 10 days (IQR, 1-91 days); P < 0.001). There was no significant difference in postoperative mortality (2.0% vs 3.6%; P = 0.49) between the two groups.

CONCLUSIONS

This study demonstrates the feasibility of creating a network for prenatal diagnosis and referral of patients with critical CHDs, such as TGA, in low-resource settings, that enables planned peripartum care in specialist pediatric cardiac centers and improved neonatal survival. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Interleukin-10 does not contribute to the anti-contractile nature of PVAT in health

Perivascular adipose tissue (PVAT) is protective and reduces contraction of blood vessels in health. PVAT is composed of adipocytes, multiple types of immune cells and stromal cells. Interleukin (IL)-10, an anti-inflammatory cytokine usually produced by T cells, B cells and macrophages, was identified as one of the highly expressed (mRNA) cytokines in the mesenteric PVAT of healthy rats. One report suggested that exogenous IL-10 causes relaxation of mouse mesenteric arteries, also suggesting that IL-10 maybe a potential anti-contractile factor. Hence, we hypothesized that PVAT-derived IL-10 causes vasorelaxation and/or reduces vasoconstriction, thus contributing to the anti-contractile nature of PVAT in health. Mesenteric arteries from rats and mice expressed the receptor for IL-10 (in tunica intima and media) as determined by immunohistochemistry. Mesenteric resistance arteries for rats and superior mesenteric artery for mice were used for isometric contractility studies. Increasing concentrations [0.4-100 ng/mL] of recombinant rat/mouse (rr/mr) IL-10 or vehicle was directly added to half-maximally constricted (phenylephrine, PE) vessels (without PVAT, with endothelium). IL-10 did not cause a direct vasorelaxation. Further, the ability of rrIL-10 to cause a rightward or downward shift of a vasoconstriction-response curve was tested in the rat. The vessels were incubated with rrIL-10 [100 ng/mL or 10 ng/mL] or vehicle for 1.5 h in the tissue bath followed by a cumulative PE [10-8-10-4 M] or U46619 [10-10-10-5 M] response curve. The maximal contractions and EC50 values were similar in IL-10 incubated vessels vs vehicle. Thus, acute exposure of exogenous IL-10 did not reduce local vasoconstriction. To further test if endogenous IL-10 from PVAT was anti-contractile, superior mesenteric arteries from IL-10 WT and KO mice, with and without PVAT, were subjected to increasing concentrations of PE. The anti-contractile nature of PVAT was preserved with both short-term and prolonged depletion (using younger and older mice, respectively) of endogenous IL-10 in males and females. Contrary to our hypothesis, PVAT-derived IL-10 neither caused vasorelaxation nor reduced local vasoconstriction directly/indirectly. Therefore, IL-10 does not contribute to the anti-contractile nature of PVAT in healthy rodents.

An instrumented glove for monitoring hand function

The measurement of hand kinematics is important for the assessment and rehabilitation of the paralysed hand. The traditional method of hand function assessment uses a mechanical or electronic goniometer placed across the joint of interest to measure the range of joint movement. Mechanical goniometers are imprecise and lack the ability to provide a dynamic measurement; electronic goniometers are expensive and cumbersome to use during therapy. An alternative to the goniometric based assessment is to use inertial motion sensors to monitor the hand movement-these can be incorporated in a glove. In this paper, we present the design of an instrumented glove equipped with Magnetic, Angular Rate and Gravity (MARG) sensors for the objective evaluation of hand function. The instrumented glove presented in this paper is designed to assess the range of movement of the hand and also monitor the hand function during the course of hand rehabilitation. Static and dynamic calibrations were performed for the Euler angles calculated from the MARG sensors. The results are also presented for physiological flexion/extension of the wrist (relative roll), flexion/extension of elbow (relative pitch), and internal rotation/external rotation (relative yaw). The static calibration results gave mean absolute errors of 4.1° for roll, 4.0° for pitch, and 4.6° for yaw. From the dynamic calibration, the speed of response to a step change gave a convergence time of 0.4 s; sinusoidally oscillating movement gave good tracking at 0.2 Hz but exhibits overshoot errors at higher frequencies which were tested to be 1 Hz. We present the results of the calibration of the instrumented glove (one sensor pair measuring one joint angle) measuring anatomical joint angles-mean absolute errors during static calibration: 6.3° for a relative roll (wrist flexion/extension), 5.0° for relative pitch (elbow flexion/extension), and 4.5° for relative yaw (shoulder internal rotation/external rotation). The experimental results from the instrumented glove are promising, and it can be used as an alternative to the traditional goniometer based hand function assessments.

An instrumented object for hand exercise and assessment using a pneumatic pressure sensor

Measurement of grip force is important for both exercise training and assessment of the hand during physical rehabilitation. The standard method uses a grip dynamometer which measures the force between the fingers and opposing thumb. The primary limitation of the grip dynamometer is the restriction of measurement to cylindrical grasps. Any deformation of the hand due to muscular or skeletal disease makes the grip dynamometer difficult or impossible to use. An alternative to the grip dynamometer is a sealed pneumatic object that can be gripped by the hand. Measurement of the internal pressure in the object can be related to the grip force. In this paper, we analyze such a pneumatic pressure sensing object for hand grip assessment and also describe an easy fabrication of the grip sensor. The instrumented object presented in this paper is designed to assess both the maximal voluntary grip forces and continuous grip force to monitor control of hand function during exercise under instruction from a therapist. Potential uses of such a pneumatic pressure sensing object for hand grip are in physical rehabilitation of patients following paralysing illnesses like stroke and spinal cord injury.

Renal angiomyoadenomatous tumour

Renal angiomyoadenomatous tumour is a newly described rare neoplasm. This tumour is characterised microscopically by admixture of three components- epithelial cells arranged in tubules and nests, angiomyomatous stroma and capillary sized interconnecting vascular channels in close association with the epithelial cell clusters. Microscopically it has wide range of differential diagnoses which include mixed epithelial and stromal tumour of kidney, angiomyolipoma and clear cell renal cell carcinoma with angiomyolipomatous/angiomyoadenomatous areas. Renal angiomyoadenomatous tumour should be differentiated from these tumours. Till now, only 10 cases have been reported in English medical literature. Here, we are reporting a case of renal angiomyoadenomatous tumour in a 29 year- old female patient who presented with hematuria and low backache and describing its main features so as to differentiate this entity from other renal tumours. To the best of our knowledge, this is the first case to be reported from India.

Ambient particulate matter induces an exacerbation of airway inflammation in experimental asthma: role of interleukin-33

High levels of ambient environmental particulate matter (PM10 i.e. < 10 μm median aerodynamic diameter) have been linked to acute exacerbations of asthma. We examined the effects of delivering a single dose of Sydney PM10 by intranasal instillation to BALB/c mice that had been sensitized to ovalbumin and challenged repeatedly with a low (≈3 mg/m(3)) mass concentration of aerosolized ovalbumin for 4 weeks. Responses were compared to animals administered carbon black as a negative control, or a moderate (≈30 mg/m(3)) concentration of ovalbumin to simulate an allergen-induced acute exacerbation of airway inflammation. Delivery of PM10 to mice, in which experimental mild chronic asthma had previously been established, elicited characteristic features of enhanced allergic inflammation of the airways, including eosinophil and neutrophil recruitment, similar to that in the allergen-induced exacerbation. In parallel, there was increased expression of mRNA for interleukin (IL)-33 in airway tissues and an increased concentration of IL-33 in bronchoalveolar lavage fluid. Administration of a monoclonal neutralizing anti-mouse IL-33 antibody prior to delivery of particulates significantly suppressed the inflammatory response induced by Sydney PM10, as well as the levels of associated proinflammatory cytokines in lavage fluid. We conclude that IL-33 plays a key role in driving airway inflammation in this novel experimental model of an acute exacerbation of chronic allergic asthma induced by exposure to PM10.

Blocking induction of T helper type 2 responses prevents development of disease in a model of childhood asthma

Early-life respiratory viral infections are linked to subsequent development of allergic asthma in children. We assessed the underlying immunological mechanisms in a novel model of the induction phase of childhood asthma. BALB/c mice were infected neonatally with pneumonia virus of mice, then sensitized intranasally with ovalbumin following recovery. Animals were challenged with low levels of aerosolized ovalbumin for 4 weeks to induce changes of chronic asthma, then received a single moderate-level challenge to elicit mild acute allergic inflammation. To inhibit the initial induction of a T helper type 2 (Th2) response, we administered neutralizing antibodies against interleukin (IL)-4 or IL-25, then assessed development of airway inflammation and remodelling. Anti-IL-4 administered during chronic challenge prevented development of chronic and acute allergic inflammation, as well as goblet cell hyperplasia/metaplasia, but features of remodelling such as subepithelial fibrosis and epithelial hypertrophy were unaffected. In contrast, anti-IL-25 had limited effects on the airway inflammatory response but prevented key changes of remodelling, although it had no effect on goblet cells. Both antibodies suppressed development of a Th2 response, while anti-IL-25 also promoted a Th17 response. In further experiments, anti-IL-25 was administered in early life alone, and again had limited effects on airway inflammation, but prevented development of airway wall remodelling. We conclude that in this murine model of childhood asthma, administration of anti-IL-4 or anti-IL-25 prevents development of some key features of asthma, suggesting that suppression of development of a Th2 response during the neonatal period or later in childhood could be effective for primary prevention.

Interferon-gamma and pulmonary macrophages contribute to the mechanisms underlying prolonged airway hyperresponsiveness

BACKGROUND

Airway hyperresponsiveness (AHR) in asthmatics includes a variable component that persists following an allergen challenge. This may be dissociated from inflammatory cell recruitment, implying a role for resident pulmonary cells in regulating the response.

OBJECTIVE

Using improved methods of assessing AHR in a mouse model of allergic airway disease, to investigate the basis of the development of prolonged AHR.

METHOD

BALB/c mice were systemically sensitized and then challenged with aerosolized ovalbumin (OVA). Airway and tissue responsiveness were measured at baseline and at 1 day, and 1, 2 and 3 weeks after the last OVA challenge. Inflammatory cell numbers in BALF and levels of mRNA for eotaxin-1 and -2, IFN-gamma, IL-5 and -13 in the lung were measured at each time-point. In further experiments, the roles of IFN-gamma and of CCR3(+) and CD4(+) cells in the development of prolonged AHR were assessed by blockade or depletion with monoclonal antibodies. The role of pulmonary macrophages was assessed by selective chemical depletion of these cells.

RESULTS

Airway responsiveness was increased above baseline at 1 day after the last OVA challenge, and this was sustained for 1 week. In contrast, tissue-specific responsiveness was only significantly increased above baseline at 1 day. Development of prolonged AHR was inhibited by neutralization of IFN-gamma or by depletion of pulmonary macrophages, but not by depletion of either CD4(+) T cells or CCR3(+) eosinophils.

CONCLUSION

An interaction between IFN-gamma and pulmonary macrophages contributed to the prolongation of airway hyperresponsiveness. In contrast, T cells and eosinophils did not contribute to prolongation of AHR. These findings emphasize the importance of the innate host response in the development of manifestations of asthma, as well as its potential relevance as a target for therapeutic intervention.

Paediatric heart care in India

There have been few systematic efforts to define the burden of paediatric heart disease in India. Estimates based on published studies on congenital heart disease (CHD) at birth suggest a massive CHD burden. Absolute numbers of children with other heart diseases are also likely to be substantial. Given the enormity of the problem the number of paediatric heart programmes and specially trained paediatric cardiologists and paediatric cardiac surgeons are woefully inadequate. They are largely clustered in those parts of India that are experiencing improving economy and human development. For the average family the cost of care of a child with heart disease is prohibitive because care of children with heart disease often requires considerable human and material resources, together with sophisticated technology. While paediatric cardiology is only now being recognised in India as a major specialty, there is a need to intensify efforts to develop the specialty especially in those parts of India where there are very few centres. The present challenges are many and they include obtaining representative data on disease burden, establishing quality institutions with comprehensive paediatric cardiac programme training a cadre of professionals for paediatric heart care, developing cost-effective management strategies and improving awareness on diagnosis and management of paediatric heart diseases.

Suppression of cytokine expression by roflumilast and dexamethasone in a model of chronic asthma

BACKGROUND

In a mouse model of mild chronic asthma, both inflammation and remodelling can be suppressed by dexamethasone (a glucocorticoid) and roflumilast (a selective phosphodiesterase-4 inhibitor).

OBJECTIVE

To better understand the underlying molecular mechanisms, we investigated the effects of treatment on airway expression of inflammation-related cytokines, as well as on epithelial expression of growth factors.

METHODS

BALB/c mice systemically sensitized to ovalbumin were challenged with aerosolized antigen for 6 weeks and treated with roflumilast or dexamethasone during the final 2 weeks. Expression of mRNA, for a variety of cytokines and growth factors, was assessed in selectively dissected proximal airways or in airway epithelium obtained by laser capture microdissection.

RESULTS

In the airway wall of vehicle-treated challenged animals, there was significantly elevated expression of mRNA for a variety of pro-inflammatory and T helper type 2 cytokines, as well as for IFN-gamma. All these cytokines were suppressed by dexamethasone. Treatment with roflumilast reduced expression of IL-17A, TNF-alpha, granulocyte-macrophage colony-stimulating factor and IL-6, but did not inhibit other cytokines. Both drugs suppressed the enhanced expression of mRNA for growth factors such as TGF-beta1 and FGF-2 in airway epithelium.

CONCLUSIONS

Whereas dexamethasone non-specifically inhibits numerous mediators involved in inflammation and the immune response, roflumilast selectively inhibits a subset of pro-inflammatory cytokines and growth factors. These mediators and/or the cells that produce them may have critical roles in the pathogenesis of the lesions of chronic asthma.

Coil occlusion of the large patent ductus arteriosus

While coil occlusion is well accepted for the small patent ductus arteriosus (PDA), occlusive devices are preferred for the larger (> 3 mm) ducts by most institutions. Because of costs concerns, occlusive devices are not always realistic in many countries. The technique of simultaneous delivery of multiple coils with bioptome assistance works well for relatively larger ducts. This technique requires careful case selection through echocardiography. The duct anatomy plays a crucial part in determining the suitability for coil occlusion. Coil occlusion has a specific advantage for relatively larger ducts in selected small children and in preterm infants because it is possible to accomplish delivery of multiple coils through relatively small introducer sheaths. In addition, aortic narrowing is less likely because coils compact in the ampulla. This review describes case selection strategies and techniques of coil occlusion of the large PDA. Relevant illustrative images are shown.

Reversibility of airway inflammation and remodelling following cessation of antigenic challenge in a model of chronic asthma

BACKGROUND

Asthma is associated with recruitment of eosinophils, accumulation of chronic inflammatory cells in the airway walls, subepithelial fibrosis and other structural changes of airway wall remodelling. The role of ongoing exposure to allergens in their pathogenesis remains unclear.

OBJECTIVE

To examine whether changes of inflammation and remodelling were reversible following cessation of antigenic challenge in a mouse model of chronic asthma.

METHODS

BALB/c mice sensitized to ovalbumin (OVA) were chronically challenged by inhalation of a low mass concentration of antigen for 8 weeks, leading to development of acute-on-chronic airway inflammation, subepithelial fibrosis and other changes of airway wall remodelling. Epithelial injury was assessed by immunohistochemistry, while inflammation and remodelling were quantified by appropriate histomorphometric techniques. Regression of lesions was assessed in animals examined at 1, 2 and 4 weeks after exposure to OVA ceased.

RESULTS

We did not find evidence of airway epithelial injury in this model of low-level chronic inhalational exposure to antigen. Persistence of the recruitment of eosinophils and chronic inflammatory cells in the airway walls was dependent on continuing antigenic challenge, as was persistence of mucous cell hyperplasia/metaplasia. Subepithelial fibrosis and epithelial hypertrophy exhibited delayed reversibility following cessation of exposure to antigen, possibly related to matrix-associated accumulation of transforming growth factor-beta(1).

CONCLUSION

In chronic asthma, low-level antigenic challenge may be required to maintain the inflammatory response in the airway wall, but airway remodelling may persist in its absence.

Desmoplastic reaction in pancreatic cancer: role of pancreatic stellate cells

OBJECTIVES

Pancreatic cancer has a very poor prognosis, largely due to its propensity for early local and distant spread. Histopathologically, most pancreatic cancers are characterized by a prominent stromal/fibrous reaction in and around tumor tissue. The aims of this study were to determine whether (1) the cells responsible for the formation of the stromal reaction in human pancreatic cancers are activated pancreatic stellate cells (PSCs) and (2) an interaction exists between pancreatic cancer cells and PSCs that may facilitate local and distant invasion of tumor.

METHODS

Serial sections of human pancreatic cancer tissue were stained for desmin and glial fibrillary acidic protein (stellate cell selective markers) and alpha-smooth muscle actin (alphaSMA), a marker of activated PSC activation, by immunohistochemistry, and for collagen using Sirius Red. Correlation between the extent of positive staining for collagen and alphaSMA was assessed by morphometry. The cellular source of collagen in stromal areas was identified using dual staining methodology, ie, immunostaining for alphaSMA and in situ hybridization for procollagen alpha1I mRNA. The possible interaction between pancreatic cancer cells and PSCs was assessed in vitro by exposing cultured rat PSCs to control medium or conditioned medium from 2 pancreatic cancer cell lines (PANC-1 and MiaPaCa-2) for 24 hours. PSC activation was assessed by cell proliferation and alphaSMA expression.

RESULTS

Stromal areas of human pancreatic cancer stained strongly positive for the stellate cell selective markers desmin and GFAP (indicating the presence of PSCs), for alphaSMA (suggesting that the PSCs were in their activated state) and for collagen. Morphometric analysis demonstrated a close correlation (r = 0.77; P < 0.04; 8 paired sections) between the extent of PSC activation and collagen deposition. Procollagen mRNA expression was localized to alphaSMA-positive cells in stromal areas indicating that activated PSCs were the predominant source of collagen in stromal areas. Exposure of PSCs to pancreatic cancer cell secretions in vitro resulted in PSC activation as indicated by significantly increased cell proliferation and alphaSMA expression.

CONCLUSIONS

Activated PSCs are present in the stromal reaction in pancreatic cancers and are responsible for the production of stromal collagen. PSC function is influenced by pancreatic cancer cells. Interactions between tumor cells and stromal cells (PSCs) may play an important role in the pathobiology of pancreatic cancer.

Successful management of isolated ventricular inversion in an adult

We report a case of isolated ventricular inversion in a 42-year-old woman. This rare congenital cardiac anomaly was corrected by an intraatrial baffle procedure. She also underwent left-sided double-chamber endocardial pacemaker implantation for postoperative tachycardia bradycardia syndrome.

Expression of growth factors by airway epithelial cells in a model of chronic asthma: regulation and relationship to subepithelial fibrosis

BACKGROUND

Growth factors produced by airway epithelial cells may be important in the pathogenesis of subepithelial fibrosis, a distinctive lesion of chronic human asthma.

OBJECTIVE

To examine the relationship between the development of subepithelial fibrosis and the expression of transforming growth factor-beta 1 (TGF-beta 1) and ligands for the epidermal growth factor receptor.

METHODS

BALB/c mice sensitized to ovalbumin were chronically challenged by inhalation of low levels of antigen, leading to development of subepithelial fibrosis and other changes of airway wall remodelling. Growth factor expression was assessed by immunohistochemistry and enzyme immunoassay.

RESULTS

Allergic sensitization directly correlated with airway epithelial expression of both the cleaved, potentially biologically active form of TGF-beta 1 and of amphiregulin in response to allergen challenge. Accumulation of TGF-beta 1 was related to remodelling of the airway wall in chronic asthma, whereas expression of amphiregulin did not exhibit a similar relationship. Production of epithelial cell-derived TGF-beta 1 appeared to be regulated by IL-13, while both IL-13 and CD4(+) T cells regulated accumulation of TGF-beta 1. In contrast to results reported in high-level exposure models of airway fibrosis, eosinophils did not appear to be a significant source of TGF-beta 1.

CONCLUSION

Airway epithelial cell-derived TGF-beta 1 has a potentially crucial role in the development of airway wall remodelling in asthma. Immunological mechanisms may regulate the release and accumulation of TGF-beta 1.

Cell migration: a novel aspect of pancreatic stellate cell biology

BACKGROUND

Pancreatic stellate cells (PSCs), implicated as key mediators of pancreatic fibrogenesis, are found in increased numbers in areas of pancreatic injury. This increase in PSC number may be due to increased local proliferation and/or migration of these cells from adjacent areas. The ability of PSCs to proliferate has been well established but their potential for migration has not been examined.

AIMS

Therefore, the aims of this study were to determine whether cultured rat PSCs have the capacity to migrate and, if so, to characterise this migratory capacity with respect to the influence of basement membrane components and the effect of platelet derived growth factor (PDGF, a known stimulant for migration of other cell types).

METHODS

Migration of freshly isolated (quiescent) and culture activated (passaged) rat PSCs was assessed across uncoated or Matrigel (a basement membrane-like substance) coated porous membranes (pore size 8 micro m) in the presence or absence of PDGF (10 and 20 ng/ml) in the culture medium. A checkerboard assay was performed to assess whether the effect of PDGF on PSC migration was chemotactic or chemokinetic.

RESULTS

Cell migration was observed with both freshly isolated and passaged PSCs. However, compared with passaged (culture activated) cells, migration of freshly isolated cells was delayed, occurring only at or after 48 hours of incubation when the cells displayed an activated phenotype. PSC migration through Matrigel coated membranes was delayed but not prevented by basement membrane components. PSC migration was increased by PDGF and this effect was predominantly chemotactic (that is, in the direction of a positive concentration gradient).

CONCLUSIONS

(i) PSCs have the capacity to migrate. (ii) Activation of PSCs appears to be a prerequisite for migration. (iii) PDGF stimulates PSC migration and this effect is predominantly chemotactic.

IMPLICATION

Chemotactic factors released during pancreatic injury may stimulate the migration of PSCs through surrounding basement membrane towards affected areas of the gland.

Dissociation of T helper type 2 cytokine-dependent airway lesions from signal transducer and activator of transcription 6 signalling in experimental chronic asthma

BACKGROUND

Type 2 T helper lymphocytes (Th2 cells) and their cytokine products are important in the pathogenesis of asthma.

OBJECTIVE

To examine the contribution of the signal transducer and activator of transcription (STAT) 6 pathway, involved in Th2 cytokine signalling, to the development of lesions of chronic asthma.

METHODS

BALB/c mice sensitized to ovalbumin were chronically challenged by inhalational of low mass concentrations of antigen for 6 weeks. Airway lesions in wild-type mice were compared with those in STAT6-deficient mice and in IL-4/13 double-deficient mice by histomorphometry and immunohistochemistry. Airway responses to methacholine were evaluated by whole-body plethysmography. Cytokine production by peribronchial lymph node cells was quantified by enzyme immunoassay.

RESULTS

STAT6-/- mice developed a variety of airway lesions that were at least equivalent to those in wild-type mice, including accumulation of intraepithelial eosinophils and of chronic inflammatory cells in the lamina propria, subepithelial fibrosis and epithelial thickening. In addition, STAT6-/- mice exhibited exaggerated airway hyper-reactivity (AHR) compared to wild-type animals. This was despite a shift from a Th2 to a Th1 pattern of immunoglobulin production by plasma cells in the inflammatory infiltrate and diminished mucous cell hyperplasia/metaplasia, together with increased production of IFN-gamma by peribronchial lymph node cells, consistent with absence of signalling via the STAT6 pathway. In contrast, gene-targeted IL-4/13-/- mice exhibited markedly diminished eosinophil recruitment and airway remodelling, as well as absence of AHR.

CONCLUSIONS

In this model, the effects of STAT6 deficiency were in marked contrast to the suppression of inflammation and AHR described in models of allergic bronchopulmonary inflammation. These results, which provide evidence of STAT6-independent AHR in an inhalational challenge model of chronic asthma, emphasize the critical effector roles of IL-4 and IL-13, as well as the need to use appropriate models to understand cytokine signalling pathways that may be potential therapeutic targets in asthma.

Macrophages at the skeletal tissue-device interface of loosened prosthetic devices express bone-related genes and their products

Aseptic loosening of prosthetic arthroplasty is the most common reason for implant failure in adult orthopaedic reconstruction. At the interface of aseptic loosened prostheses, there is an abundance of particle-activated macrophages and other inflammatory cells. The role of these particle-laden macrophages in the osteogenic arm of the remodeling skeleton in this pathological condition is poorly understood. Molecular signaling by mesenchymal cells and mononuclear inflammatory cells residing in the interfacial tissues between bone and cement or prosthetic material of aseptically loosened joint prostheses was studied using in situ hybridization and immunohistochemical techniques. We found that a range of collagenous and noncollagenous matrix proteins, including osteopontin, osteocalcin, bone sialoprotein, and type I collagen, were produced in the periprosthetic tissue by foamy macrophages, as well as nearby osteogenic cells. The former accumulated in profusion in the three zones of interfacial tissues: pseudomembranous, fibrous, and osseous. Spindle mesenchymal cells in the fibrous zone failed to express any of the osteogenic mRNAs or proteins sought. The expression of bone-related genes and proteins by foamy macrophages at the interface of an aseptic loosened prosthesis may contribute to the disturbance of bone remodeling at this site.

Expression and distribution of matrix metalloproteinases and their inhibitors in the human iris and ciliary body

AIM

To determine the expression and distribution of matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) in the normal human iris and ciliary body.

METHODS

Seven postmortem human eyes were fixed with formalin. The iris and ciliary body were dissected out and embedded in paraffin. The expression of MMPs -1, 2, 3, and 9, and TIMPs 1-4 in the iris and ciliary body was determined by a novel immunofluorescence technique and the results graded by masked observers.

RESULTS

Positive staining for MMPs and TIMPs was observed in all regions of the anterior uvea, and was more intense in the ciliary body than in the iris. Most MMPs and TIMPs showed similar patterns in their distribution. In the ciliary body, staining was strongest in the epithelium, and was localised to the epithelial cell cytoplasm, except for TIMP-3 which was strongly expressed in the basement membranes. In the iris, staining was most noticeable in the anterior border and anterior epithelial layer. Blood vessels in the stroma of the iris and ciliary body also stained moderately for MMPs and TIMPs.

CONCLUSION

Both MMPs and TIMPs are widely expressed in the anterior uvea, with a positive correlation between their expressions. Their differential localisation in the ciliary body suggests they may have a role in maintaining homeostasis in the uveal tract.

Role of interleukin-13 in eosinophil accumulation and airway remodelling in a mouse model of chronic asthma

BACKGROUND

Interleukin-13 is believed to be important in asthmatic inflammation and airway hyper-reactivity.

OBJECTIVE

To investigate the role of IL-13 in chronic asthma, using an improved experimental model of asthma that reproduces most of the morphological features of the human disease.

METHODS

BALB/c mice or gene-targeted mice deficient in their ability to produce IL-13 or the IL-4 receptor alpha-chain (IL-4Ralpha) were sensitized to ovalbumin and exposed to aerosolized antigen for 30 min/day on 3 days/week for 6 weeks. Intraepithelial eosinophils, accumulation of chronic inflammatory cells in the airway wall, subepithelial fibrosis, epithelial hypertrophy and numbers of mucous cells were quantified histomorphometrically. Airway hyper-reactivity (AHR) to a cholinergic agonist was assessed by barometric plethysmography.

RESULTS

Compared with wild-type animals, IL-13 -/- mice exhibited diminished accumulation of eosinophils and chronic inflammatory cells, as well as reduced subepithelial fibrosis, epithelial hypertrophy and mucous cell hyperplasia (P < 0.01 for all comparisons). In contrast, AHR was still demonstrable in IL -13 -/- mice. In IL-4Ralpha -/- mice the inflammatory response, subepithelial fibrosis and AHR were similar to wild-type mice, although the receptor-deficient mice had significantly less epithelial hypertrophy and mucous cell hyperplasia.

CONCLUSION

These results imply a critical role for IL-13 in accumulation of intraepithelial eosinophils in chronic asthma, as well as in epithelial and subepithelial remodelling. In addition, they suggest that in chronic asthma, IL-13 may be capable of signalling via a pathway that does not involve IL-4Ralpha.

Neuropeptides and nerve growth in inflammatory bowel diseases: a quantitative immunohistochemical study

Many studies have indicated changes in neuropeptides in inflammatory bowel disease (IBD), but with contradictory results. Nerve growth factor also has a potential role in the maintenance of enteric nerves and may be associated with IBD. A quantitative immunohistochemical method was used to measure area density of immunoreactive nerves in the colonic mucosa of surgical specimens. No significant differences in immunoreactivity for substance P, vasoactive intestinal polypeptide, growth associated protein 43, and the neurotrophin receptor p75 were seen in the control, Crohn's, and ulcerative colitis groups. Compared to age-matched normal colon (N = 18), there was an increase in neutrophil number in Crohn's (P < 0.05) and ulcerative colitis (P < 0.01) (both N = 9). There were positive correlations (P < 0.05) between neutrophil number and growth associated protein, between p75 and substance P immunoreactive nerves in ulcerative colitis, and between p75 and vasoactive intestinal polypeptide in Crohn's specimens. These data indicate a link between the immunologic and nervous systems in IBD.

The pathology of human and murine pulmonary infection with Cryptococcus neoformans var. gattii

Human infection by Cryptococcus neoformans var. neoformans is well characterised and usually occurs in immunocompromised patients. Less is known about infection by Cryptococcus neoformans var. gattii, which usually produces disease in previously normal individuals. In two cases of human pulmonary infection by Cryptococcus neoformans var. gattii, we observed a mixed inflammatory pattern, including granulomas associated with numerous T lymphocytes and a lymphocytic interstitial pneumonitis with B lymphocytes and formation of follicles. We also established a murine model of pulmonary infection by Cryptococcus neoformans var. gattii, which reproduced most of these features. This model is likely to prove useful in studies of the pathogenesis of this infection.

Emergency transcatheter balloon recanalization of acutely thrombosed modified Blalock-Taussig shunts

BACKGROUND

Modified Blalock-Taussig shunts are used to palliate a variety of cyanotic heart diseases associated with reduced pulmonary blood flow. Acute shunt thrombosis in patients with shunt-dependent pulmonary blood flow can result in life-threatening hypoxia. We describe our experience of emergency transcatheter recanalization in 5 severely hypoxic children with acute shunt occlusion.

METHODS AND RESULTS

Five patients with ages ranging between 5 and 24 months (median 11 months) and weight ranging from 4 to 8 kg (median 5 kg) presented with severe hypoxia, acidosis and hypotension following acute occlusion of modified Blalock-Taussig shunts placed 11 days to 12 months ago. As severe hypoxia (saturation range 3 5%-5 0%), acidosis and a state of shock in all the patients increased the risk for a redo surgical procedure, they were taken up for emergency transcatheter recanalization within 2-6 hours of hospitalization. This was done by positioning a Judkin's right coronary catheter at the mouth of the thrombosed shunt, crossing the shunt with a guidewire and serial dilatations with coronary and/or peripheral angioplasty balloons to the size of the graft. This technique was immediately successful in 4 of the 5 patients, thereby avoiding a repeat palliative operation. In 2 patients with residual stenosis, stents were used to restore luminal patency. One patient with acute stent thrombosis was managed successfully with local delivery of thrombolysis for 36 hours, which resulted in good luminal patency. At follow-up after 6 and 12 months, the shunts in both the stented patients are patent, with an oxygen saturation of 78% and 80%, respectively. In 2 other patients who had undergone plain balloon angioplasty, the shunts remained patent for 11 days (died of bronchopneumonia and septicemia) and 3 months, respectively. The procedure was unsuccessful in one very sick patient in whom the shunt had a tortuous course.

CONCLUSIONS

Transcatheter recanalization of an acutely thrombosed Blalock-Taussig shunt is feasible. It can offer satisfactory short-term palliation in selected patients. Stents may play a role in patients with residual narrowing after dilatation. The procedure can be expeditiously accomplished in an emergency situation in a severely hypoxic child and may be a realistic alternative to surgery or thrombolysis.

Bioptome-assisted simultaneous delivery of multiple coils for occlusion of the large patent ductus arteriosus

We describe a novel method that allows bioptome-assisted delivery of multiple Gianturco coils simultaneously for occlusion of the large patent ductus arteriosus (PDA). Two or more coils were intertwined at one end and held by a bioptome (5.2 Fr) and pulled into a short introducer. The coils were then deployed in the PDA via a long sheath (7-11 Fr) previously placed across the duct via the femoral vein. Twelve patients (6 months to 64 years; median, 10.5 years) with large PDAs (4.7 +/- 1.3 mm; range, 3.1-8.4 mm; PA mean pressure, 40 +/- 17 mm Hg; pulse pressure 63 +/- 18 mm Hg) underwent bioptome-assisted occlusion with multiple coils at our institutions. The procedure was uneventful in nine patients (fluoroscopy time, 6-23 min) and prolonged in three patients (fluoroscopy time, 26, 72, and 120 min) because of dislodgment of the coil mass and embolization of an additional coil. Successful coil deployment was feasible in all patients. Three patients required repeat coil deployment for flow elimination (hemolysis occurred in two). Flow elimination was demonstrated on the last follow-up evaluation in all except two patients. One infant has developed significant left pulmonary artery stenosis. Bioptome-assisted PDA occlusion using multiple coils delivered simultaneously may be a promising alternative to devices for transcatheter closure of large PDAs. Cathet Cardiovasc Intervent 2001;54:95-100.

Understanding airway wall remodeling in asthma: a basis for improvements in therapy?

Current strategies for the management of asthma focus on suppressing airway inflammation. Other characteristic features of human asthma, such as airway hyperreactivity and the structural changes collectively referred to as airway remodeling, are largely ignored in existing guidelines for monitoring the effectiveness of treatment. Evidence is accumulating that pharmacologic therapy targeting airway wall remodeling may be valuable in treating asthma. However, development of appropriate therapeutic agents will require a better understanding of the pathogenesis of remodeling, which appears to be regulated by a variety of cytokines and growth factors produced by inflammatory, epithelial, and stromal cells. Furthermore, testing the effectiveness of novel agents that specifically target the process of remodeling will require appropriate experimental models, but most currently available animal models of asthma have major limitations. A recently described murine model of chronic human asthma offers considerable potential for dissection of the mechanisms of airway wall remodeling, as well as for investigation of the therapeutic potential of drugs that can modulate chronic inflammation and remodeling.

Dimeric S100A8 in human neutrophils is diminished after phagocytosis

S100A8 is a major cytoplasmic protein of neutrophils and monocytes/macrophages and has been associated with myeloid cell differentiation and activation. Little is known about its functions or mechanisms of release from neutrophils. We have developed a monoclonal antibody to murine S100A8, which cross-reacts with human S100A8. This antibody, which recognizes the homodimeric form of the protein, detects its expression specifically in human neutrophils and is reactive in formalin-fixed, paraffin-embedded tissues. Using this antibody as well as a commercially available antibody to human S100A8, we show that phagocytic activation of neutrophils, in vivo in acute appendicitis and in vitro following phagocytosis of opsonized zymosan, is characterized by loss of cytoplasmic immunoreactivity for S100A8. In vitro, phagocytosis is associated with rapid diminution of immunostaining without loss of viability. Loss of immunoreactivity for S100A8 may serve as a marker of localized neutrophil activation in tissues.

RNA-catalyzed amino acid activation

We have selected RNAs that perform a new reaction that chemically activates amino acids, paralleling mixed phosphate anhydride synthesis by protein aminoacyl-transfer RNA synthetases. Care with recovery of the unstable reaction product was apparently essential to this selection. The best characterized RNA, KK13, requires only Ca2+ for reaction and is optimally active at low pH with KM = 50 mM and kcat = 1.1 min(-1) for activation of leucine. In conjunction with previous RNA-catalyzed aminoacyl-RNA synthesis, peptide bond formation, and RNA-based coding, these amino acid-activating RNAs complete an experimental demonstration that the four fundamental reactions of protein biosynthesis can be RNA-mediated. The appearance of translation in an RNA world is therefore supported.

Urinary tract infections in children. Tips for a family physician

BACKGROUND

Urinary tract infections in children are the second most common bacterial infection requiring medical attention. Despite this, precise definition and management of urinary tract infection in children can be quite evasive for the unwary family physician.

OBJECTIVE

This article provides a few tips for the busy family practitioner to help manage this problem.

DISCUSSION

Much debate still abounds in relation to this issue. However, untreated urinary tract infections in childhood can result in unacceptable morbidity in adulthood. Hence aggressive management of urinary tract infections in children and identifying children 'at risk' remains our top priority.

Murine model of chronic human asthma

Human asthma is associated with acute and chronic inflammation of the airway mucosa, accompanied by airway wall remodelling. Experimental models of acute allergic bronchopulmonary inflammation in mice are useful for investigation of immunological mechanisms and of cellular recruitment, but have significant limitations because they fail to reproduce a number of characteristic lesions of human asthma, while usually being associated with marked alveolitis. We have developed an improved murine model of asthma that exhibits almost all of the morphological and functional changes that typify the human disease, without any confounding alveolitis. This model has considerable potential for the investigation of pathogenetic mechanisms and potential treatments of chronic human asthma.

Molecular structures of carbonyl-linked bis(dioxolene) complexes: can a carbonyl group act as an effective ferromagnetic coupler?

Molecular structures of two bis(ZnIIdioxolene) complexes are described: (TpCum,MeZn)(2)1-H2 (C106H123.50B2N12O10Zn2), tetragonal, P4/ncc, a = 25.1810(2) A, b = 25.1810(2) A, c = 34.7744(2) A, alpha = 90 degrees, beta = 90 degrees, gamma = 90 degrees, Z = 8; (TpCum,MeZn)(2)1-H (C101H120B2N12O6Zn2), triclinic, P1, a = 13.6624(2) A, b = 13.80920(10) A, c = 26.62340(10) A, alpha = 96.6910(10) degrees, beta = 91.8560(10) degrees, gamma = 109.0190(10) degrees, Z = 2. One of the complexes, (TpCum,MeZn)(2)1-H2, has two protonated catecholate ligands, while the other complex, (TpCum,MeZn)(2)1-H, has one protonated catecholate and one semiquinone ligand. When reacted with PbO2, a labile S = 1, bis(ZnIIsemiquinone) complex is formed in which the two semiquinones are attached to a common carbonyl group.

Operative outcome and intermediate term follow-up of neonatal Blalock-Taussig shunts

BACKGROUND

The neonatal age group is considered to be one of the important risk factors for perioperative morbidity and mortality as well as poor long-term patency following Blalock-Taussig shunts.

METHODS AND RESULTS

Out of a total of 190 patients who underwent Blalock-Taussig shunts in our institute between July 1998 and July 2000, 20 patients were aged less than 30 days and this neonatal cohort was studied retrospectively. The mean age was 18+/-11 days (range: 3-30 days). The mean weight of the babies was 3.1+/-0.7 kg, the smallest weighed 2.1 kg. The cardiac anatomy was tetralogy of Fallot with pulmonary atresia in 6, pulmonary atresia with intact ventricular septum in 3, tricuspid atresia in 5 and complex single ventricle physiology in the rest. All patients were deeply cyanotic and preoperative prostaglandin E1 was needed in 10 patients to ensure ductal patency and maintain oxygen saturations prior to the shunt operation. The mean hilar right and left pulmonary artery sizes were 3.99+/-0.44 mm and 3.69+/-0.79 mm, respectively. Three patients (15%) had significant stenosis at the site of duct insertion. The shunts were accomplished with 3.5 mm polytetrafluoroethylene grafts in 7 patients (35%) and 4 mm in the rest. The mean duration of mechanical ventilation was 2.0+/-2.83 days, one patient who developed bronchopneumonia needed prolonged ventilation for 14 days. The mean intensive care unit stay was 4.79+/-2.66 days. The mean hospital stay was 11.7+/-6.4 days. Five patients who developed sepsis stayed beyond 14 days. There were 3 deaths (immediate post-operative shock and possibly shunt malfunction in 1, bronchopneumonia in 1 and late shunt thrombosis at 3 months in 1). Two patients had late shunt block, one of those mentioned above and the other at 3 months secondary to infective endarteritis of the right pulmonary artery. All these infants received 4 mm grafts. All the 3.5 mm grafts were patent at follow-up. Seventeen patients were alive and well at follow-up (mean: 9 months, range: 3-21 months) with a mean resting systemic oxygen saturation of 77% (66%-95%).

CONCLUSIONS

The overall shunt patency rate after neonatal Blalock-Taussig shunt is about 80% on intermediate term follow-up. A smaller graft size (3.5 mm) does not appear to be an incremental risk factor for shunt blockade and operative mortality.

Expression of the alphaEbeta7 integrin by mast cells in rheumatoid synovium

OBJECTIVE

Rheumatoid synovitis is characterized by a mast cell response in which tryptase containing mast cells (MCT) associate with T lymphocyte infiltration, and tryptase and chymase containing mast cells (MCTC) correlate more closely with tissue damage or repair events. We investigated expression of the alphaEbeta7 integrin and its ligand E-cadherin in rheumatoid and normal synovium and compared this expression to synovial mast cell responses.

METHODS

Immunohistochemical analysis was used to determine the expression of alphaEbeta7 and E-cadherin in rheumatoid (n = 17) and normal (n = 6) synovium. The density of MCT and MCTC mast cell subsets was compared to the density of alphaEbeta7 positive mast cells.

RESULTS

The mean density of alphaEbeta7 positive cells in rheumatoid synovia was 25.2 cells/mm2 (range 0.3-102.9), of which 26.7% (range 0-68.6%) were mast cells. A mean of 11.9% (range 0-30.4%) of rheumatoid synovial mast cells expressed alphaEbeta7 compared to 0% in normal synovium (p < 0.0001). There was a strong correlation between the density of alphaEbeta7 positive cells and the total mast cell density in rheumatoid synovium (r2= 0.74). alphaEbeta7 positive mast cell density correlated significantly with the MCT subset density (r2 = 0.5, p = 0.014), but not with the MCTC subset density. E-cadherin expression was increased in rheumatoid compared with normal synovium, but did not colocalize or correlate with alphaEbeta7 expression.

CONCLUSION

These results indicate a role for alphaEbeta7 in the mast cell response that occurs in rheumatoid synovitis, in particular the MCT mast cell subset expansion associated with inflammatory events and interactions with infiltrating lymphocytes.

Meningococcal infections and meningitis: what is new?

Meningococcal infection is one of the very few severe bacterial infections, in this era, that still can kill a relatively healthy child within minutes. Fortunately, it is a relatively rare disease. Rural practitioners may see one affected child once every 2-3 years, but once seen they will never forget it. The present article gives some examples of case scenarios along with a brief overview of the problem, with emphasis on early diagnosis, prevention and possible future developments.

Vascular remodelling in chronic inflammatory periodontal disease

Periodontitis is a chronic inflammatory disease of the highly vascularised supporting tissues of the teeth. Little is known about the vascular changes in untreated advanced periodontitis. Using confocal immunofluorescence microscopy and morphometry, we defined and quantified vascular remodelling in this lesion. In the connective tissue subjacent to the altered epithelium lining of the periodontal pocket, there was a significant increase in the numerical density of vascular profiles, primarily accounted for by vessels > or = 25 microm in diameter. In addition, vascular basement membranes were thickened and there was accumulation of non-vascular basement membrane remnants. We investigated the distribution of major angiogenic growth factors in periodontitis using immunohistochemistry. Basic fibroblast growth factor, although consistently associated with blood vessels, showed no regional variation in its distribution. In contrast, there was a marked regional variation in the intensity of immunostaining for vascular endothelial growth factor, with significantly reduced staining of the pocket epithelium. The changes in the vascularity of the periodontal connective tissues in untreated advanced periodontitis may be, in part, a consequence of altered expression of angiogenic activity by the epithelium. In turn, this may reflect the epithelial response to microbial flora in the microenvironment of the periodontal pocket.

Airway inflammation in a murine model of chronic asthma: evidence for a local humoral immune response

BACKGROUND

Asthma is an acute-on-chronic inflammatory disease of the airways characterized by recruitment of eosinophils into the epithelial layer, chronic inflammation in the lamina propria, as well as variable accumulation of mast cells in the airway wall. The role of local production of allergen-specific immunoglobulins in triggering mast cell-mediated asthmatic inflammation is unknown.

METHODS

We used a chronic inhalational exposure model of asthma in ovalbumin-sensitized BALB/c mice to examine the phenotype of immunoglobulin-secreting cells and mast cells in the airway wall. In parallel, we assayed ovalbumin-specific IgG and total IgE in the plasma of these animals.

RESULTS

In sensitized mice exposed to aerosolized ovalbumin for 6 weeks, aggregates of chronic inflammatory cells consisted of a majority of plasmacytoid cells, including numerous IgG-synthesizing cells, which were significantly increased in sensitized animals compared to controls. IgA-synthesizing cells were also present, but were not increased in the sensitized exposed mice. Immunoglobulins in the cytoplasm of the plasma cells were demonstrated to be antigen-specific. No IgM-or IgE-synthesizing cells were observed, although levels of total IgE in the plasma were significantly increased. There was no recruitment of mast cells of either the mucosal or the connective tissue phenotype into the lamina propria or the epithelium.

CONCLUSION

In this experimental model of chronic asthma, the pattern of inflammation in the airway wall is consistent with development of a local IgG-mediated humoral immune response. However, there is no evidence of local production of IgE or recruitment of mast cells.

Expression patterns of E-cadherin, involucrin, and connexin gap junction proteins in the lining epithelia of inflamed gingiva

The structural integrity and functional differentiation of the lining epithelium were studied in relation to inflammatory changes associated with destructive periodontitis. In the different regions of lining epithelia from clinically healthy gingiva and periodontitis, comparisons were made of the expression patterns of E-cadherin, which is critical in intercellular adhesion; of proteins associated with gap junction communication channels; and of involucrin, which is a key marker of differentiation in stratified epithelia. Filamentous actin (F-actin), which is important in cell structural integrity, attachment, and migration, was also examined. Semiquantitative immunohistochemical analysis revealed that in both clinically healthy gingiva and lesions of advanced periodontitis, expression patterns of E-cadherin, involucrin, and connexins 26 and 43 were similar, with a statistically significant reduction in staining intensity from the external oral epithelium, through the gingival sulcus, to the junctional epithelium or pocket epithelium, respectively. Furthermore, there was a striking reduction in staining for E-cadherin, involucrin, and both connexins in the pathological lining epithelium of the periodontal pocket. These changes were associated with marked alterations of filamentous actin expression, collectively indicating profound perturbation of the epithelial structure. The data reported support the concept that the ability of the pathological lining epithelium to function as an effective barrier against the ingress of microbial products into the tissues is severely compromised.

Dissociation of inflammatory and epithelial responses in a murine model of chronic asthma

To study pathogenetic mechanisms in chronic asthma, we employed a novel experimental model that replicates characteristic features of the human disease. Chronic inflammation and epithelial changes, specifically localized to the airways, were induced by repeated exposure of systemically sensitized BALB/c mice to low mass concentrations of aerosolized ovalbumin for 6 weeks. The contribution of Th2 cytokine-driven inflammation to the development of airway lesions and hyperreactivity was assessed in cytokine-deficient mice. In interleukin-5-deficient animals, intraepithelial eosinophils and chronic inflammatory cells in the lamina propria of the airways were markedly decreased; however, these animals developed epithelial hypertrophy and subepithelial fibrosis comparable with that observed in sensitized wild type mice. Airway hyperreactivity to inhaled methacholine did not develop in interleukin-5-deficient mice. In contrast, interleukin-4-deficient mice exhibited no decrease in airway inflammation, but had significantly greater epithelial hypertrophy and subepithelial fibrosis, as well as exaggerated hyperreactivity to methacholine. We conclude that interleukin-5, but not interleukin-4, plays a central role in the development of chronic inflammation of the airways and the induction of airway hyperreactivity. Furthermore, chronic epithelial and fibrotic changes occur independently of interleukin-5 and are not required for the development of airway hyperreactivity. The dissociation between airway wall remodeling and airway hyperreactivity has important implications for therapeutic approaches to chronic asthma.

Bronchial asthma: recent advances

Asthma is one of the oldest diseases about which there are lots of myths in most parts of the world. The exact cause of this global disease still eludes scientists. The recent knowledge about the pathogenesis of the disease, led to rationalise the medications into different groups. Parallel to the increasing incidence of this disease, is the knowledge about the trigger factors and steps to reduce their exposure. Childhood asthma is a lot different from asthma in adults, as many children won't be able to use the inhalers like adults and most children will not be able to do lung function tests until they are about 6 years of age. Unlike for any other diseases, research has helped year after year in developing new strategies for management of asthma. Starting from definition of the disease to inventing newer medications, management of asthma has revolutionised in the last few years and has also accounted for the decreasing mortality in many countries. This article tries to give an overview of bronchial asthma in children including recent advances and possible future developments.

Substrate preference profiles of proteases released by allergenic pollens

BACKGROUND

Pollens are important triggers for allergic asthma and seasonal rhinitis. We have recently reported that proteases released by major allergenic pollens can injure airway epithelial cells in vitro. Disruption of epithelial integrity by proteases released following deposition of pollens on mucosal surfaces could promote sensitization and induce inflammation.

OBJECTIVE

To compare protease activities released by allergenic pollens of various genera.

METHODS

We used a rapid microassay which quantifies cleavage of dipeptide ester substrates to characterize the substrate preference profiles of serine proteases in diffusates of the pollens of perennial ryegrass (Lolium perenne), Kentucky blue grass (Poa pratensis), Bermuda grass (Cynodon dactylon), Western ragweed (Ambrosia spp.), white birch (Betula spp.) and Sydney golden wattle (Acacia longifolia).

RESULTS

Comparison of the profiles revealed notable differences as well as similarities between serine protease activities released by these pollens. Diffusates of Kentucky blue grass pollen exhibited very high substrate preference for arginine and lysine. For other pollens, cleavage of the cysteine substrate was usually the most rapid and was associated with marked preference for leucine and methionine. There was considerable variation between these pollens in the rates of cleavage of the histidine substrate. In addition, we observed high rates of cleavage of arginine and lysine substrates by Acacia pollen diffusate.

CONCLUSION

At least two dominant patterns of substrate preference are identifiable in the mixtures of proteases released by hydrated pollens. Purification of the proteases responsible for these patterns of activity will facilitate investigation of their role in airway epithelial injury and allergic disease.

Culture and characterisation of epithelial cells from human pterygia

BACKGROUND/AIMS

Pterygia are a common disorder of the ocular surface. The disease represents a chronic fibrovascular and degenerative process thought to originate at the conjunctival-corneal junction, where altered limbal stem cells are proposed to be the cell of origin. Extensive epidemiological evidence exists to implicate ultraviolet B irradiation in the pathogenesis of pterygia. To date no animal or in vitro culture model has been developed to test such an hypothesis. The aim of this study was to establish and characterise a pure population of epithelial cells derived from pterygium tissue.

METHODS

Tissue specimens were obtained from patients undergoing pterygium excision. Explants were cultured in either serum free or serum supplemented medium. Primary and passaged cells were processed for light microscopy, analysed by flow cytometry, and characterised immunohistochemically using specific antibodies.

RESULTS

In serum free culture, cuboidal cells with typical morphology of epithelial cells migrated from the pterygium explants from 3 days onwards and eventually formed a cohesive monolayer. Passaged cells consisted of 98.4% cytokeratin positive cells and demonstrated immunoreactivity for multiple cytokeratins, including AE1, AE3, AE5, but were negative for AE8. These cells also expressed an epithelial specific antigen, together with vimentin and mucin, as did epithelial cells in sections of pterygia.

CONCLUSIONS

A relatively simple method of isolating pterygium epithelial cells has been established. Cultured pterygium epithelial cells are phenotypically and functionally similar to their in vivo counterparts with respect to keratin, vimentin, and mucin expression. In vitro assays using these cells may aid in elucidating the pathogenesis of pterygia.

Improved double immunofluorescence for confocal laser scanning microscopy

Reliable double immunofluorescence labeling for confocal laser scanning microscopy requires good separation of the signals generated by the fluorochromes. We have successfully overcome the limitation of a single argon ion laser in achieving effective excitation of dyes with well-separated emission spectra by employing the novel sulfonated rhodamine fluorochromes designated Alexa 488 and Alexa 568. The more abundant antigen was visualized using the red-emitting Alexa 568, with amplification of the signal by a biotinylated bridging antibody and labeled streptavidin. This was combined with the green-emitting Alexa 488, which yielded brighter images than fluorescein but exhibited comparable photodegradation. With appropriate controls to ensure the absence of crosstalk between fluorescence channels, these dyes permitted unequivocal demonstration of co-localization. This combination of fluorochromes may also offer advantages for users of instruments equipped with alternative laser systems.