Airway smooth muscle thickness in asthma is related to severity but not duration of asthma.

Asthma is characterised by an increased airway smooth muscle (ASM) area (ASM(area)) within the airway wall. The present study examined the relationship of factors including severity and duration of asthma to ASM(area). The perimeter of the basement membrane (PBM) and ASM(area) were measured on transverse sections of large and small airways from post mortem cases of fatal (n = 107) and nonfatal asthma (n = 37) and from control subjects (n = 69). The thickness of ASM (ASM(area)/PBM) was compared between asthma groups using multivariate linear regression. When all airways were considered together, ASM(area)/PBM (in millimetres) was increased in nonfatal (median 0.04; interquartile range 0.013-0.051; p = 0.034) and fatal cases of asthma (0.048; 0.025-0.078; p<0.001) compared with controls (0.036; 0.024-0.042). Compared with cases of nonfatal asthma, ASM(area)/PBM was greater in cases of fatal asthma in large (p<0.001) and medium (p<0.001), but not small, airways. ASM(area)/PBM was not related to duration of asthma, age of onset of asthma, sex or smoking. No effect due to study centre, other than that due to sampling strategy, was found. The thickness of the ASM layer is increased in asthma and is related to the severity of asthma but not its duration.

Informed consent for the study of retained tissues from postmortem examination following sudden infant death.

OBJECTIVE: To develop an approach for seeking informed consent to examine tissues retained from a previous study of sudden infant death syndrome (SIDS) as part of a study on asthma, and to document responses and participation rate. DESIGN: Pilot open-ended approach to 10 volunteer SIDS parents, followed by staged approach (newsletter, mail and telephone call) to seek consent from the target SIDS families for the asthma study. PARTICIPANTS: Parents (n = 10) of SIDS infants known to SIDS and Kids Victoria and parents of SIDS infants (n = 107) from the 1991-2 SIDS in Victoria case-control study. MAIN OUTCOMES: Qualitative responses of the piloted parents and study parents, and participation rates. RESULTS: The pilot group responses were used to refine the written material to be provided. Of the 72 families for which contact details were available, 45 gave verbal consent for contact by the Victorian Institute of Forensic Medicine regarding the asthma study, three refused and 24 did not respond to two letters. Thirty-three completed consent forms, all positive for participation in the asthma study, giving a positive response rate of 73% (33/45). CONCLUSIONS: The use of postmortem tissue for research is acceptable to the next of kin when an approach is sensitive to their concerns and needs and is made by experienced counsellors from a familiar organisation. Despite the painful memories evoked by the approach of the research group, the acceptance rate among those who could be contacted was high.

Time to death, airway wall inflammation and remodelling in fatal asthma.

Fatal asthma is characterised pathologically by airway wall remodelling, eosinophil and neutrophil infiltration, accumulation of mucus in the airway lumen and smooth muscle shortening. The durations of fatal attacks of asthma show a clear bimodal distribution. Airway smooth muscle contraction and the accumulation of luminal mucus may contribute to death from asthma and relate to time to death. The current authors have examined these two components in uninflated lung tissue in cases of fatal asthma from the second Victorian asthma mortality study. Based on time from onset of symptoms to death, cases fell into two distinct groups: short course <3 (1.5+/-0.6 mean+/-sd) h; and long course >8 (12.3+/-5.9) h. Short course cases had more muscle shortening, higher levels of salbutamol and higher ratios of neutrophils to eosinophils than long course cases, who tended to have more mucus in the lumen. In conclusion, this study confirms the dichotomy of both time to death and the eosinophil/neutrophil ratio in cases of fatal asthma. It suggests that in short course cases acute airway narrowing is due, predominantly, to bronchoconstriction despite higher blood levels of salbutamol. Mucus accumulation may be more important in long course cases.

Technique for preparing high-quality microphotographs by fluorescence microscopy.

Simple techniques resulting in high-quality microphotographs by fluorescence microscopy are described for the preparation of Salmonella cultures and slides.

Isolation of salmonellae from pork carcasses.

Four hundred and twenty pork carcasses from four abattoirs were examined for the presence of salmonellae by use of swabbing-enrichment techniques and contact plate methods. Carcasses from only one abattoir were found to be contaminated by swabbing-enrichment (23.3%) and contact plate (17.9%) methods. The area of the skin side of the ham, near the anal opening, was determined to be the area to examine for isolating salmonellae from pork carcasses with the greatest frequency. The most frequently isolated species of salmonellae in this study were Salmonella derby, S. anatum, S. typhimurium, and S. indiana.