A national policy on asthma management for schools. The Asthma Special Interest Group, Thoracic Society of Australia and New Zealand

Since asthma is the most common chronic illness in childhood, many of the problems associated with this condition will impact on the child's education. Because of widespread concerns regarding the management of asthma in schools, a subcommittee of the Thoracic Society of Australia and New Zealand, Asthma Special Interest Group, was convened to draw up national guidelines for school staff in order to provide optimal management of asthma in the school setting. We used current medial literature and the clinical experience of the authors who have dealt with children and adolescents suffering from asthma in the hospital, community and school environment. A number of issues had been identified, including: the availability of an asthma first aid kit; correct use of bronchodilator aerosols by puffer and spacer devices; and clear instructions as to when to notify parents and when to call an ambulance to the school.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparative study of four glass ionomer luting cements during post pull-out tests

OBJECTIVES

The aim of this study was to compare the maximum loads and modes of failure of four glass ionomer luting cements during post pull-out tests.

METHODS

The cements studied included two based on conventional glass ionomer cement chemistry, i.e., a hand-mixed cement and an encapsulated cement, and two based on the newer light-cured chemistry, i.e., a restorative cement used at a low powder:liquid ratio and an experimental luting cement. One hundred and forty bovine incisors were cut 13 mm from the apex and prepared with post channels, 1.75 mm in diameter and 9 mm long. Ni-Cr-Mb bonding alloy posts were cast and sandblasted prior to cementation into the roots with each of the cements. Twenty-four hours later, pull-out tests were carried out at a strain rate of 0.5 mm/min. The maximum loads and modes of failure were noted. The data obtained were analyzed using a Kruskal-Wallis test followed by comparison of groups using Mann-Whitney tests.

RESULTS

Comparison of the maximum loads revealed a significant difference between the conventional encapsulated cement and all other cements. Weibull analysis of the results gave values for the Weibull moduli and probabilities of survival for a post under a given load for each cement and indicated that the newer cements performed better than the conventional cements.

SIGNIFICANCE

Further research into the in vitro and in vivo behavior of the resin-modified glass ionomer cements in clinical situations where light-curing is not possible is justified.

Identification and characterization of the phosphatidylinositol-(4, 5)-bisphosphate 5-phosphatase in human platelets

Phosphatidylinositol (4,5)-bisphosphate (PtdIns(4,5)-P2) is the precursor of several second messenger molecules. In unstimulated cells PtdIns(4,5)P2 is hydrolyzed by a PtdIns(4,5)P2 5-phosphatase to form phosphatidylinositol 4-phosphate (PtdIns(4)P) which is subsequently recycled to phosphatidylinositol. PtdIns(4,5)P2 5-phosphatase activity was detected in platelet cytosolic and particulate fractions. The platelet PtdIns(4,5)P2 5-phosphatase activity was magnesium but not calcium dependent. The elution profile of platelet cytosolic PtdIns(4,5)P2 5-phosphatase from anion exchange resins, exactly matched that of the 75-kDa inositol-polyphosphate 5-phosphatase (Ins(1,4,5)P3 5-phosphatase). The latter is a signal terminating enzyme responsible for the hydrolysis of inositol (1,4,5)-trisphosphate (Ins(1,4,5)P3) to inositol (1,4)-bisphosphate (Mitchell, C.A., Connolly, T.M., and Majerus, P.W. (1989) J. Biol. Chem. 264, 8873-8877). Polyclonal antibodies raised against recombinant 75-kDa Ins(1,4,5)P3 5-phosphatase specifically immunoprecipitated all PtdIns-(4,5)P2 5-phosphatase activity from both the platelet membrane and cytosolic fractions. Purified 75-kDa Ins(1,4,5)P3 5-phosphatase hydrolyzed PtdIns(4,5)P2 forming PtdIns(4)P (Km = 250 microM). By contrast, purified membrane-associated 43-kDa Ins(1,4,5)P3 5-phosphatase did not hydrolyze PtdIns(4,5)P2. In the unstimulated platelet, recycling of PtdIns-(4,5)P2 to PtdIns(4)P is mediated by the 75-kDa Ins-(1,4,5)P3 5-phosphatase.

Stabilization of pH in solid-matrix hydroponic systems

2-[N-morpholino]ethanesulfonic acid (MES) buffer or Amberlite DP-1 (cation-exchange resin beads) were used to stabilize substrate pH of passive-wicking, solid-matrix hydroponic systems in which small canopies of Brassica napus L. (CrGC 5-2, genome : ACaacc) were grown to maturity. Two concentrations of MES (5 or 10 mM) were included in Hoagland 1 nutrient solution. Alternatively, resin beads were incorporated into the 2 vermiculite : 1 perlite (v/v) growth medium at 6% or 12% of total substrate volume. Both strategies stabilized pH without toxic side effects on plants. Average seed yield rates for all four pH stabilization treatments (13.3 to 16.9 g m-2 day-1) were about double that of the control (8.2 g m-2 day-1), for which there was no attempt to buffer substrate pH. Both the highest canopy seed yield rate (16.9 g m-2 day-1) and the highest shoot harvest index (19.5%) occurred with the 6% resin bead treatment, even though the 10 mM MES and 12% bead treatments maintained pH within the narrowest limits. The pH stabilization methods tested did not significantly affect seed oil and protein contents.

Lower respiratory tract symptoms in Queensland schoolchildren: risk factors for wheeze, cough and diminished ventilatory function

BACKGROUND

The occurrence of respiratory symptoms and abnormal lung function in children is known to be influenced by genetic and many environmental factors. The association between specific respiratory symptoms in children of school age and their parents has been examined.

METHODS

Respiratory symptoms and ventilatory function were recorded for 4549 schoolchildren in Queensland, Australia.

RESULTS

The cumulative prevalence of wheezing was 23.1% of 8 year olds and 20.8% of 12 year olds, and the prevalence of wheezing within the previous 12 months was 13.9% and 10.5% respectively. A parental history of asthma or wheeze and hayfever was associated with wheeze in the child, but did not affect either the age of onset or frequency of episodes. A history of frequent cough in children who had never wheezed was associated with a parental history of frequent bronchitis, but less strongly with parental wheeze. These familial aggregations were not mediated by common exposure to cigarette smoke. Both a history of parental wheeze and maternal cigarette use were associated with a decrease in FEF25-75 in the child and these effects were additive.

CONCLUSIONS

The association of specific symptoms (wheeze and cough without wheeze) in parent and offspring is interpreted as evidence for different mechanisms of familial transmission, which may be genetic.

Purification and characterisation of a snake venom phospholipase A2: a potent inhibitor of platelet aggregation

An inhibitor of human platelet aggregation was identified from the venom of an Australian Copperhead snake, Austrelaps superba, as a novel phospholipase A2. The inhibitor was purified to homogeneity by chromatography on Q-Sepharose, S-Sepharose and C8 reverse phase HPLC. The purified phospholipase A2 has a molecular weight of 15 kDa as assessed by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). N-terminal sequence analysis of the platelet inhibitor revealed 70-80% sequence identity to other previously described secretory phospholipase A2. Phospholipase activity of the purified protein was confirmed by the ability of the enzyme to hydrolyse lecithin. Pretreatment of the purified protein with the specific phospholipase A2 inhibitor p-bromophenacyl bromide, resulted in abrogation of both its enzyme and platelet inhibitory activity. The phospholipase A2 inhibited platelet aggregation and serotonin release, induced by a variety of platelet agonists, in a time and dose dependent manner.

Trace elements and organochlorines in the shoalgrass community of the lower Laguna Madre, Texas

Our objectives were to measure concentrations of seven trace elements and 14 organochlorine compounds in sediment and biota of the shoalgrass (Halodule wrightii) community of the lower Laguna Madre of south Texas and to determine whether chemicals associated with agriculture (e.g. mercury, arsenic, selenium, organochlorine pesticides) were highest near agricultural drainages. Arsenic, mercury, selenium, lead, cadmium, and organochlorines were generally at background concentrations throughout the lower Laguna Madre. Nickel and chromium concentrations were exceptionally high in shrimp and pinfish (Lagodon rhomboides), which is difficult to explain because of no known anthropogenic sources for these trace elements. For sediment and blue crabs (Callinectes sapidus), mercury was highest near agricultural drainages. Also, DDE was more frequently detected in blue crabs near agricultural drainages than farther away. In contrast, selenium concentrations did not differ among collecting sites and arsenic concentrations were lowest in shoalgrass, blue crabs, and brown shrimp (Penaeus aztecus) near agricultural drainages.

The role of bioregenerative life-support systems in a manned future in space

Thus far in the manned space program, human life support has depended on storage of air, water, food, and energy. There are no refrigerators on Shuttle, and fresh foods are limited to what can be stowed in lockers for the first 3 days of a mission, when spoilage becomes a factor. Oxygen is stored, CO2 is scrubbed, and water is stored and treated. As we approach the Space Station era, life support will be a combination of storage and resupply. Duty cycles will be 90 days, and physico-chemical (P/C) systems will be important for recycling oxygen and water. Nutritionists seek a capability for refrigerated storage of fresh food on Station. However, most food still will be thermostabilized, rehydratables that can be stored at room temperature. Present Shuttle food is not much more sophisticated than repackaged camp food, and tends to be high in salt content. Hopefully, menus will be healthier on Station, where dietary countermeasures against biomedical responses to chronic microgravity might be implemented, and certainly need to be studied.

Purification and characterization of a 43-kDa membrane-associated inositol polyphosphate 5-phosphatase from human placenta

We have identified, isolated, and characterized a membrane-associated inositol polyphosphate 5-phosphatase (5-phosphatase) from the particulate fraction of human placenta. The enzyme was purified 3700-fold from a detergent extract of human placental membranes to apparent homogeneity, by chromatography on DEAE-Sepharose, S-Sepharose, hydroxylapatite, and Biosil SEC 250 HPLC gel filtration. The purified 5-phosphatase has a molecular mass of 43 kDa as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration chromatography. The enzyme hydrolyzes inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) to inositol 1,4 bisphosphate (Ins(1,4)P2) with an apparent Km of 5 microM. The 43-kDa 5-phosphatase also hydrolyzes inositol 1,3,4,5-tetrakisphosphate (Ins(1,3,4,5)P4) with an apparent Km of 1.2 microM. The enzyme requires Mg2+ ions for activity and is inhibited by Ca2+ concentrations greater than 100 microM. Polyclonal antibodies developed against the membrane-associated enzyme immunoprecipitate the purified membrane-associated placental 5-phosphatase and the platelet Type I cytosolic enzyme, but not the 75-kDa platelet Type II 5-phosphatase. These results demonstrate that the purified membrane 5-phosphatase bears physical and immunological similarity with the Type I cytosolic platelet enzyme.

Studies on the evolution and function of different forms of the mouse myogenic gene Myo-D1 and upstream flanking region

The product of the murine Myo-D1 gene is able to initiate the complete sequence of genetic events required for formation of skeletal muscle. Because efficiency of regeneration of skeletal muscle is more pronounced in SJL/J mice, as compared to other strains, differences in the structure of Myo-D1 and the upstream regulatory region were sought to determine whether efficiency of tissue repair was influenced by the structure of the gene itself. Analysis of the restriction-fragment length polymorphism (RFLP) of genomic DNA from SJL/J and different sub-strains of mouse indicated that there are at least three different structural forms of Myo-D1, one of which is unique to SJL/J mice and may have been derived from a double recombinational event involving founder forms of Myo-D1. The unique form of Myo-D1 in SJL/J mice also exhibits a PvuII RFLP upstream from the gene, which may reflect some form of rearrangement or variation in methylation of a potential Myo-D1-binding region. Reference to the size of fragments hybridising with the Myo-D1 probe, following digestion of genomic DNA with TaqI, suggests that in most tissues, adenine residues within Myo-D1 may be extensively methylated. Segregation of Myo-D1 allotypes with response to mechanical injury to skeletal muscle in F2 offspring derived from SJL/J and BALB/c parental strains reveals that increased efficiency of tissue repair is associated with the SJL/J type of Myo-D1 gene. These observations provide new approaches to investigation of genetic control of tissue regeneration and cellular differentiation and proliferation in general.

Synthesis and structure-activity relationships of some 6 beta-acrylamido penicillins

Syntheses are described for penicillins (4b approximately 4i, 5a and 5b) which possess a 6 beta-(2-heteroaryl-3-substituted)-propenamido side-chain of fixed geometry. In vitro results for these compounds against a range of Gram-positive and Gram-negative bacteria showed in most cases good stability against both penicillinase and TEM-1 beta-lactamase; analogues (4b approximately 4i) bearing a 2-(2-aminothiazol-4-yl) unit showed the best intrinsic activity, the cyclohexyl compound (4b) being the most promising. The 1-acetoxyethyl ester (6) of 4b was also prepared; in experimental animal studies the in vivo properties of this compound compared favourably with cefuroxime axetil and are reported together with selected in vivo data for the other compounds.

A model for clinical teaching and learning

A set of criteria to observe clinical teaching was developed and used to describe and evaluate the teaching behaviour of 24 tutors of medical students in their initial clinical skill term. The tutors had no previous instruction in teaching techniques, nor had their teaching been previously evaluated. The criteria used focus on six basic dimensions: the teaching/learning environment; the degree of intellectual challenge; the degree of interaction; the logical structure of teaching sessions; the quality of teaching skills; and the modelling of professional skills and attitudes. A continuum of teaching behaviour was observed in each dimension, with most tutors demonstrating adequate levels of performance in each. The tutors all strongly supported the evaluation and the feedback they received. Their subsequent teaching behaviour will be reviewed to assess the impact of this feedback.

A semi-empirical model for prediction of how post-retained crowns will fail under compressive loading

The aim of this in vitro study was to determine the relative contributions to retention of the different components of the post-retained crown and the mode of failure when the crown was loaded at 50 degrees to the vertical (i.e., in an apical direction). Failure was initiated in all the specimens as a rotation of the crown about a point on the labial surface of the root at the crown-root interface with pull-out of the post. A semi-empirical model was developed to explain this mode of failure. From experimental results, it was noted that the retention provided by the post was the most significant factor in the equation. However, large variation in the maximum forces recorded from pull-out tests on 40 posts suggested that the glass-ionomer cement was acting in the manner of a brittle composite material whose failure may be attributed to defects in the structure causing stress concentrations. The probability of survival at each ultimate strength recorded experimentally was plotted for comparison with the curve generated by the derived Weibull function. Close agreement was noted. Thus, for any given force applied compressively at 50 degrees to the vertical to a post-retained crown of known dimensions, it is possible, by use of the described equation, to calculate the force, P, applied to the post. This value of P may then be inserted into the Weibull equation to give the probability of the crown failing under that applied force.

Corticosteroids in acute severe asthma: effectiveness of low doses

BACKGROUND

Although the need for corticosteroids in acute severe asthma is well established the appropriate dose is not known.

METHODS

The response to intravenous hydrocortisone 50 mg (low dose), 100 mg (medium dose), and 500 mg (high dose), administered every six hours for 48 hours and followed by oral prednisone, was compared in patients with acute asthma in a double blind randomised study. After initial emergency treatment with bronchodilators subjects received oral theophylline or intravenous aminophylline and nebulised salbutamol four hourly. Patients were given low, medium, or high doses of intravenous hydrocortisone and then 20, 40, or 60 mg/day respectively of oral prednisone with a reducing regimen over the following 12 days. Beclomethasone dipropionate, 400 micrograms twice daily by metered dose inhaler, was also started. Peak expiratory flow (PEF), forced expiratory volume in one second (FEV1), and visual analogue dyspnoea scores (VAS) were recorded daily in hospital and PEF and VAS twice daily after discharge for a total of 12 days.

RESULTS

The 66 subjects (40 female) who completed the study had a mean (SD) age of 31(14) years. On presentation mean (SD) FEV1% predicted in the low (n = 22), medium (n = 20), and high dose (n = 24) groups was 17(13), 19(12), and 19(11) and after emergency bronchodilator treatment 32(20), 30(12), and 36(13). After 24 hours of treatment the respective post-bronchodilator FEV1% predicted values were 62(22), 62(23), and 65(28) compared with 71(24), 69(22), and 71(24) after 48 hours. No significant difference between the groups was detected. PEF and VAS improved with treatment over the 12 days but was not influenced by steroid dose.

CONCLUSIONS

Hydrocortisone 50 mg intravenously four times a day for two days followed by low dose oral prednisone is as effective in resolving acute severe asthma as 200 or 500 mg of hydrocortisone followed by higher doses of prednisone.

Cellular differences in the regeneration of murine skeletal muscle: a quantitative histological study in SJL/J and BALB/c mice

Skeletal muscle regeneration in SJL/J and BALB/c mice subjected to identical crush injuries is markedly different: in SJL/J mice myotubes almost completely replace damaged myofibres, whereas BALB/c mice develop fibrotic scar tissue and few myotubes. To determine the cellular changes which contribute to these differential responses to injury, samples of crushed tibialis anterior muscles taken from SJL/J and BALB/c mice between 1 and 10 days after injury were analysed by light and electron microscopy, and by autoradiography. Longitudinal muscle sections revealed about a 2-fold greater total mononuclear cell density in SJL/J than BALB/c mice at 2 to 3 days after injury. Electron micrographs identified a similar proportion of cell types at 3 days after injury. Autoradiographic studies showed that the proportions of replicating mononuclear cells in both strains were similar: therefore greater absolute numbers of cells (including muscle precursors and macrophages) were proliferating in SJL/J muscle. Removal of necrotic muscle debris in SJL/J mice was rapid and extensive, and by 6 to 8 days multinucleated myotubes occupied a large part of the lesion. By contrast, phagocytosis was less effective in BALB/c mice, myotube formation was minimal, and fibrotic tissue conspicuous. These data indicate that the increased mononuclear cell density, more efficient removal of necrotic muscle, together with a greater capacity for myotube formation in SJL/J mice, contribute to the more successful muscle regeneration seen after injury.

Geriatric trauma: a case study

Major advances in health care have made it possible for a greater number of people to live to advanced age and thereby be exposed to the same risk of injury as the younger segment of the population. Elderly trauma victims, however, possess unique needs that must be addressed. Comorbidity, the aging process, and its relationship to the response to injury, as well as ethical and moral dilemmas such as "do not resuscitate" decisions and cost of care, need to be investigated. Although advanced age clearly predisposes one to an increase in mortality, mortality has also been correlated with complications that develop during the hospital stay. Trauma, especially involving the elderly, is a rich area for nursing research, and a refined knowledge base contributes to improving the quality of trauma care.

bFGF enhances the development of the collateral circulation after acute arterial occlusion

An adequate collateral circulation is crucial to tissue survival subsequent to proximal major arterial occlusion. The precise mechanism of collateral blood vessel development and the biochemical mediators involved in this process are unknown. To evaluate the influence of a number of agents on the development of the collateral circulation, we developed a rat model of severe hind limb ischaemia. The recovery of blood flow after acute arterial occlusion was increased by exogenous basic fibroblast growth factor and heparin, and decreased by protamine. Erucamide (cis-13-docosenamide), an angiogenic lipid, had no effect on collateral blood flow. These results indicate that basic fibroblast growth factor and heparin are potential therapeutic agents in the treatment of peripheral vascular disease.

Asthma morbidity in Australia: an epidemiological study

OBJECTIVE

To examine the prevalence and management of asthma in adults and children in a population sample in eastern Australia.

SETTING

A random sample of children from 33 primary schools in Sydney, Melbourne, Brisbane, and the Upper Hunter Valley (New South Wales), and their parents.

DESIGN

A cross-sectional analytic survey of 8753 primary school children aged between 5 and 12 years, and their parents (n = 13,945 adults). Asthma prevalence and management practices were determined by parental responses to a questionnaire, and spirometry was performed in children with "probable asthma".

RESULTS

Of 8753 children whose parents responded, the prevalence of current wheeze was 19.5% and diagnosed asthma was 17.1%. Of the children with "probable asthma", 30% had their lung function measured in the previous year, and 6% possessed both a peak flow meter and an action plan for their asthma. Undertreatment was likely, as preventive asthma medications (inhaled corticosteroids or sodium cromoglycate) were used regularly by only 25.5% of these children and by 44.3% of children who had asthma symptoms more than twice per week. Children with the diagnosis of asthma reported higher rates of preventive medication use and ventilatory function measurement than children with frequent symptoms without the diagnosis. In the 13,945 adults, the reported prevalence of asthma was 7%, of whom 39% were using preventive medications, 34% had their ventilatory function assessed in the previous year, and 7% had both a peak flow meter and an asthma action plan.

CONCLUSIONS

The study illustrated the gap between the current level of asthma management in the community and the standards set by the Thoracic Society of Australia and New Zealand. Undertreatment and suboptimal management of asthma remain important problems in Australia.