Pepsin measured in induced sputum - a test for pulmonary aspiration in children?

Purpose The purpose of this study was to investigate if pepsin measured in sputum is a useful marker of pulmonary aspiration secondary to gastroesophageal reflux (GER) in children. It is possible that the induced sputum procedure could cause GER and invalidate the results. The hypothesis stated that healthy children (those without history of respiratory or gastroesophageal symptoms) would not have pepsin detected in induced sputum. Methods Children attending surgical outpatients in the Royal Belfast Hospital for Sick Children (Belfast, Northern Ireland) were recruited. After spirometry, sputum was obtained by induction with hypertonic 3% saline. Spirometry was repeated, and complications were noted. An “in-house” enzyme-linked immunosorbent assay was used to measure pepsin concentration in sputum. The lower limit of detection of pepsin was 1.19 ng/mL. Results Children (n = 21) aged 4 to 16 years were recruited. Twenty children completed the study. No adverse effects were reported. Pepsin was detected in 17 (85%) of 20 sputum samples. Conclusions The act of sputum induction appears to induce physiologic GER in a healthy childhood population. The analysis of pepsin in sputum obtained by sputum induction is therefore not useful in the investigation of reflux-related respiratory disease.

From Aspiration to Action: A Learning Intentions Model to Promote Critical Engagement with Science in the Print-Based Media

Science programmes which prepare students to read critically and respond thoughtfully to science-based reports in the media could play an important role in promoting informed participation in the public debate about issues relating to science, technology and society. Evidence based guidance about the practice and pattern of use of science-based media in the classroom is limited. This study sought to identify learning intentions that teachers believe ought to underpin the development of programmes of study designed to achieve this end-result. Teachers views of knowledge, skills and attitudes required to engage critically with science-based news served as a basis for this study. Teachers developed a pedagogical model by selecting appropriate statements of learning intentions, grouping these into coherent and manageable themes and coding them according to perceived level of difficulty. The model is largely compatible with current curricular provision in the UK, highlights opportunities for interdisciplinary collaboration and illustrates the developmental nature of the topic.

EXPERT-SYSTEM SUPPORT USING BAYESIAN BELIEF NETWORKS IN THE DIAGNOSIS OF FINE-NEEDLE ASPIRATION BIOPSY SPECIMENS OF THE BREAST

Aim-To develop an expert system model for the diagnosis of fine needle aspiration cytology (FNAC) of the breast.

Methods-Knowledge and uncertainty were represented in the form of a Bayesian belief network which permitted the combination of diagnostic evidence in a cumulative manner and provided a final probability for the possible diagnostic outcomes. The network comprised 10 cytological features (evidence nodes), each independently linked to the diagnosis (decision node) by a conditional probability matrix. The system was designed to be interactive in that the cytopathologist entered evidence into the network in the form of likelihood ratios for the outcomes at each evidence node.

Results-The efficiency of the network was tested on a series of 40 breast FNAC specimens. The highest diagnostic probability provided by the network agreed with the cytopathologists' diagnosis in 100% of cases for the assessment of discrete, benign, and malignant aspirates. A typical probably benign cases were given probabilities in favour of a benign diagnosis. Suspicious cases tended to have similar probabilities for both diagnostic outcomes and so, correctly, could not be assigned as benign or malignant. A closer examination of cumulative belief graphs for the diagnostic sequence of each case provided insight into the diagnostic process, and quantitative data which improved the identification of suspicious cases.

Conclusion-The further development of such a system will have three important roles in breast cytodiagnosis: (1) to aid the cytologist in making a more consistent and objective diagnosis; (2) to provide a teaching tool on breast cytological diagnosis for the non-expert; and (3) it is the first stage in the development of a system capable of automated diagnosis through the use of expert system machine vision.

Pepsin in bronchoalveolar lavage fluid:a specific and sensitive method of diagnosing gastro-oesophageal reflux-related pulmonary aspiration

Gastro-oesophageal reflux (GOR)-related aspiration is associated with respiratory disease, but the current "gold standard" investigation, the lipid-laden macrophage index (LLMI), is flawed. A specific marker of GOR-related aspiration should originate in the stomach, but not the lung. An assay to detect gastric pepsin in the bronchoalveolar lavage (BAL) of children was developed and validated.

Ectopic bone formation in rapidly fabricated acellular injectable dense collagen-Bioglass hybrid scaffolds via gel aspiration-ejection

Gel aspiration-ejection (GAE) has recently been introduced as an effective technique for the rapid production of injectable dense collagen (IDC) gel scaffolds with tunable collagen fibrillar densities (CFDs) and microstructures. Herein, a GAE system was applied for the advanced production and delivery of IDC and IDC-Bioglass® (IDC-BG) hybrid gel scaffolds for potential bone tissue engineering applications. The efficacy of GAE in generating mineralizable IDC-BG gels (from an initial 75-25 collagen-BG ratio) produced through needle gauge numbers 8G (3.4 mm diameter and 6 wt% CFD) and 14G (1.6 mm diameter and 14 wt% CFD) was investigated. Second harmonic generation (SHG) imaging of as-made gels revealed an increase in collagen fibril alignment with needle gauge number. In vitro mineralization of IDC-BG gels was confirmed where carbonated hydroxyapatite was detected as early as day 1 in simulated body fluid, which progressively increased up to day 14. In vivo mineralization of, and host response to, acellular IDC and IDC-BG gel scaffolds were further investigated following subcutaneous injection in adult rats. Mineralization, neovascularization and cell infiltration into the scaffolds was enhanced by the addition of BG and at day 21 post injection, there was evidence of remodelling of granulation tissue into woven bone-like tissue in IDC-BG. SHG imaging of explanted scaffolds indicated collagen fibril remodelling through cell infiltration and mineralization over time. In sum, the results suggest that IDC-BG hybrid gels have osteoinductive properties and potentially offer a novel therapeutic approach for procedures requiring the injectable delivery of a malleable and dynamic bone graft that mineralizes under physiological conditions