Cardiopulmonary and cerebrovascular acclimatization in children and adults at 3800 m

Maturational differences exist in cardiopulmonary and cerebrovascular function at sea-level, but the impact of maturation on acclimatization responses to high altitude is unknown. Ten children (9.8 ± 2.5 years) and 10 adults (34.7 ± 7.1 years) were assessed at sea-level (BL), 3000 m and twice over 4 days at 3800 m (B1, B4). Measurements included minute ventilation ( V ̇ E ${\dot{V}}_{\rm{E}}$ ), end-tidal partial pressures of oxygen ( P ETO 2 ${P}_{{\rm{ETO}}_{\rm{2}}}$ ) and carbon dioxide, echocardiographic assessment of pulmonary artery systolic pressure (PASP) and stroke volume (SV) and ultrasound assessment of blood flow through the internal carotid and vertebral arteries was performed to calculate global cerebral blood flow (gCBF). At 3000 m, V ̇ E ${\dot{V}}_{\rm{E}}$ was increased from BL by 19.6 ± 19.1% (P = 0.031) in children, but not in adults (P = 0.835); SV was reduced in children (-11 ± 13%, P = 0.020) but not adults (P = 0.827), which was compensated for by a larger increase in heart rate in children (+26 beats min^-1 vs. +13 beats min^-1 , P = 0.019). Between B1 and B4, adults increased V ̇ E ${\dot{V}}_{\rm{E}}$ by 38.5 ± 34.7% (P = 0.006), while V ̇ E ${\dot{V}}_{\rm{E}}$ did not increase further in children. The rise in PASP was not different between groups; however, ∆PASP from BL was related to ∆ P ETO 2 ${P}_{{\rm{ETO}}_{\rm{2}}}$ in adults (R²  = 0.288, P = 0.022), but not children. At BL, gCBF was 43% higher in children than adults (P = 0.017), and this difference was maintained at high altitude, with a similar pattern and magnitude of change in gCBF between groups (P = 0.845). Despite V ̇ E ${\dot{V}}_{\rm{E}}$ increasing in children but not adults at a lower altitude, the pulmonary vascular and cerebrovascular responses to prolonged hypoxia are similar between children and adults. KEY POINTS: Children have different ventilatory and metabolic requirements from adults, which may present differently in the pulmonary and cerebral vasculature upon ascent to high altitude. Children (ages 7-14) and adults (ages 23-44) were brought from sea level to high altitude (3000 to 3800 m) and changes in ventilation, pulmonary artery systolic pressure (PASP) and cerebral blood flow (CBF) were assessed over 1 week. Significant increases in ventilation and decreases in left ventricle stroke volume were observed at a lower altitude in children than adults. PASP and CBF increased by a similar relative amount between children and adults at 3800 m. These results help us better understand age-related differences in compensatory responses to prolonged hypoxia in children, despite similar changes in pulmonary artery pressure and CBF between children and adults.

Exploring the Impact and Acceptance of Wearable Sensor Technology for Pre- and Postoperative Rehabilitation in Knee Replacement Patients: A U.K.-Based Pilot Study

Knee replacement operations are common, highly successful procedures that are increasing in frequency. The COVID-19 pandemic has emphasized the need for innovative care pathways that reduce face-to-face appointments. We report on the impact of introducing a wearable sensor for pre- and postoperative rehabilitation of 21 knee replacement patients at 2 hospitals in the U.K.

Pilot feasibility study to detect mesenchymal stem cell biomarkers of bronchopulmonary dysplasia in the tracheal aspirate fluid of preterm infants

OBJECTIVE

This study aimed to detect novel mesenchymal stem cell peptides/biomarkers of bronchopulmonary dysplasia (BPD) in the tracheal aspirate fluid (TAF) of preterm infants.

STUDY DESIGN

Participants included infants less than 32 weeks' gestational age or birth weight under 1500 grams who required endotracheal intubation and mechanical ventilation within first 24 hours of life. TAF sample collection was performed at the time of the first clinically indicated routine suctioning. Standardization curves for human levels of osteopontin (Opn), macrophage colony stimulating factor 1 (Csf1), transforming growth factor beta 1 (TGF-β1), and secretory immunoglobulin A (sIgA) were generated for 15 enrolled participants.

RESULTS

We demonstrated that stem cell biomarkers are secreted into the TAF of preterm infants and their concentrations can be easily measured during the first week of life.

CONCLUSIONS

Further studies are warranted to determine a causal relationship between these biomarkers and BPD development and severity.

Molybdenum distributions and variability in drinking water from England and Wales

An investigation has been carried out of molybdenum in drinking water from a selection of public supply sources and domestic taps across England and Wales. This was to assess concentrations in relation to the World Health Organization (WHO) health-based value for Mo in drinking water of 70 μg/l and the decision to remove the element from the list of formal guideline values. Samples of treated drinking water from 12 water supply works were monitored up to four times over an 18-month period, and 24 domestic taps were sampled from three of their supply areas. Significant (p < 0.05) differences were apparent in Mo concentration between sources. Highest concentrations were derived from groundwater from a sulphide-mineralised catchment, although concentrations were only 1.5 μg/l. Temporal variability within sites was small, and no seasonal effects (p > 0.05) were detected. Tap water samples collected from three towns (North Wales, the English Midlands, and South East England) supplied uniquely by upland reservoir water, river water, and Chalk groundwater, respectively, also showed a remarkable uniformity in Mo concentrations at each location. Within each, the variability was very small between houses (old and new), between pre-flush and post-flush samples, and between the tap water and respective source water samples. The results indicate that water distribution pipework has a negligible effect on supplied tap water Mo concentrations. The findings contrast with those for Cu, Zn, Ni, Pb, and Cd, which showed significant differences (p < 0.05) in concentrations between pre-flush and post-flush tap water samples. In two pre-flush samples, concentrations of Ni or Pb were above drinking water limits, although in all cases, post-flush waters were compliant. The high concentrations, most likely derived from metal pipework in the domestic distribution system, accumulated during overnight stagnation. The concentrations of Mo observed in British drinking water, in all cases less than 2 μg/l, were more than an order of magnitude below the WHO health-based value and suggest that Mo is unlikely to pose a significant health or water supply problem in England and Wales.

Application of a simple multiplicative spatio-temporal stream water quality model to the river Conwy, North Wales

We use a simple multiplicative spatio-temporal model to describe variability in a sequence of water quality monitoring data from headwater streams in the Conwy catchment, North Wales. The spatial component of the model treats concentrations as due to simple mixing of a small number of distinct source types, each associated with particular upstream catchment characteristics. The temporal component allows concentration variability due to seasonal or hydrological change. We apply the model using three candidate catchment characteristic classifications to generate mixing concentrations, and a seasonal component to describe temporal variability, and test a range of sub-models. We identify a cross-classification of soil and land cover as providing the best spatial indicator of water quality of the classifications considered. The spatial model based on a selected grouped cross-classification was shown to account for between 35% and 90% of the spatial variability and the seasonal model accounted for between 45% and 100% of the temporal variability in the data. Analysis of residuals showed an inverse relationship between DOC and sulphate and between hydrogen ion concentration and calcium and magnesium. We also found residual correlations between sites which are strongly related to landscape class. These are attributed to landscape class by time interactions which are not accounted for in the simple multiplicative model.

Predicting nitrogen and acidity effects on long-term dynamics of dissolved organic matter

Increases in dissolved organic carbon (DOC) fluxes may relate to changes in sulphur and nitrogen pollution. We integrated existing models of vegetation growth and soil organic matter turnover, acid-base dynamics, and organic matter mobility, to form the 'MADOC' model. After calibrating parameters governing interactions between pH and DOC dissolution using control treatments on two field experiments, MADOC reproduced responses of pH and DOC to additions of acidifying and alkalising solutions. Long-term trends in a range of acid waters were also reproduced. The model suggests that the sustained nature of observed DOC increases can best be explained by a continuously replenishing potentially-dissolved carbon pool, rather than dissolution of a large accumulated store. The simulations informed the development of hypotheses that: DOC increase is related to plant productivity increase as well as to pH change; DOC increases due to nitrogen pollution will become evident, and be sustained, after soil pH has stabilised.

Nitrogen concentrations in mosses indicate the spatial distribution of atmospheric nitrogen deposition in Europe

In 2005/6, nearly 3000 moss samples from (semi-)natural location across 16 European countries were collected for nitrogen analysis. The lowest total nitrogen concentrations in mosses (<0.8%) were observed in northern Finland and northern UK. The highest concentrations (≥ 1.6%) were found in parts of Belgium, France, Germany, Slovakia, Slovenia and Bulgaria. The asymptotic relationship between the nitrogen concentrations in mosses and EMEP modelled nitrogen deposition (averaged per 50 km × 50 km grid) across Europe showed less scatter when there were at least five moss sampling sites per grid. Factors potentially contributing to the scatter are discussed. In Switzerland, a strong (r(2) = 0.91) linear relationship was found between the total nitrogen concentration in mosses and measured site-specific bulk nitrogen deposition rates. The total nitrogen concentrations in mosses complement deposition measurements, helping to identify areas in Europe at risk from high nitrogen deposition at a high spatial resolution.

Skeletal muscle growth in young rats is inhibited by chronic exposure to IL-6 but preserved by concurrent voluntary endurance exercise

Childhood diseases are often accompanied by chronic inflammation, which is thought to negatively impact growth. Interleukin-6 (IL-6) is typically cited as an indicator of inflammation and is linked to impaired growth. This study was designed to isolate and identify potential effects of chronic IL-6 exposure on skeletal muscle growth during development. A second aim was to determine if endurance exercise, thought to antagonize chronic inflammation, would interact with any effects of IL-6. The muscles of one leg of rapidly growing rats were exposed to IL-6 or vehicle for 14 days. Subgroups of IL-6-infused rats were provided access to running wheels. Local IL-6 infusion resulted in approximately 13% muscle growth deficit (myofibrillar protein levels). Exercise (>4,000 m/day) prevented this deficit. IL-6 infusion increased mRNA for suppressor of cytokine signaling-3 (SOCS3) and tumor necrosis factor-alpha (TNF-alpha), and this was not prevented by exercise. IL-6 infusion increased the mRNAs for atrogin, insulin-like growth factor-I (IGF-I), and IGF binding protein-4 (IGFBP4), and these effects were mitigated by exercise. Exercise stimulated an increase in total RNA ( approximately 19%) only in the IL-6-infused muscle, suggesting that a compensatory increase in translational capacity was required to maintain muscle growth. This study indicates that IL-6 exposure during periods of rapid growth in young animals can retard growth possibly via interactions with key growth factors. Relatively high volumes of endurance-type exercise do not exacerbate the negative effects of IL-6 and in fact were found to be beneficial in protecting muscle growth.

Idiopathic polyneuritis in SPF chickens

Paralysis due to peripheral neuritis occurred sporadically in a flock of Rhode Island Red chickens over a period of 8 years and is named idiopathic neuritis (IP). The flock was housed in isolators and free from many common pathogens including all known neurotropic viruses of chickens. The pathology of the nerve lesions, including their ultrastructure, is described and comparisons made with the lesions of Marek's disease and experimental allergic neuritis in chickens. Demyelination with invasion of nerve fibres with lymphocytes and macrophages occurs in all three diseases but there are differences in lesion distribution and intensity of cellular infiltration. The closest similarity is between the lesions of IP and the B-type lesions of Marek's disease. Attempts to isolate a cytopathic virus and to transmit the disease by inoculation failed to demonstrate an infectious causal agent. An autoimmune response to normal nerve is suggested as the most likely aetiology amongst several alternatives. The heritability of IP is not established, but the disease has not been detected in a light Sussex flock maintained under similar conditions.

Aedes Dronc: a novel ecdysone-inducible caspase in the yellow fever mosquito, Aedes aegypti

Caspases are cysteinyl-aspartate-specific proteases known for their role in apoptosis. Here, we describe the characterization of Aedes Dronc, a novel caspase in the yellow fever mosquito, Aedes aegypti. Aedes Dronc is predicted to contain an N-terminal caspase recruitment domain and is a homologue of Drosophila Dronc and human caspase-9. An increase in transcripts and caspase activity coincides with developmental changes in the mosquito, suggesting that Aedes Dronc plays a role in developmental apoptosis. Exposure of third instar larvae to ecdysone resulted in a significant increase in both transcript levels and caspase activity. We present here a functional characterization of the first caspase recruitment domain-containing caspase in mosquitoes, and will initiate studies on the role of apoptosis in the innate immune response of vectors.

Exhaled methyl nitrate as a noninvasive marker of hyperglycemia in type 1 diabetes

Recent technical advances allow detection of several hundred volatile organic compounds (VOCs) in human exhaled air, many of which reflect unidentified endogenous pathways. Our group has previously estimated plasma glucose levels in healthy adults during a standard oral glucose tolerance test via exhaled VOC analysis. As a result of the metabolic characteristics of hyperglycemia in the diabetic (low insulin and increased free fatty acids and ketones), we hypothesized that different exhaled VOC profiles may be present in children with type 1 diabetes mellitus (T1DM) during spontaneous hyperglycemia. Exhaled methyl nitrate strongly correlated specifically with the acute, spontaneous hyperglycemia of T1DM children. Eighteen experiments were conducted among 10 T1DM children. Plasma glucose and exhaled gases were monitored during either constant euglycemia (n = 5) or initial hyperglycemia with gradual correction (n = 13); all subjects received i.v. insulin and glucose as needed. Gas analysis was performed on 1.9-liter breath samples via gas chromatography using electron capture, flame ionization, and mass selective detection. Among the approximately 100 measured exhaled gases, the kinetic profile of exhaled methyl nitrate, commonly present in room air in the range of 5-10 parts per trillion, was most strongly statistically correlated with that of plasma glucose (P = 0.003-0.001). Indeed, the kinetic profiles of the two variables paralleled each other in 16 of 18 experiments, including repeat subjects who at different times displayed either euglycemia or hyperglycemia.

Safety and effect of transforming growth factor-beta(2) for treatment of venous stasis ulcers

Transforming growth factor-beta(2) promotes healing in a variety of animal models and exhibits clinical effects thought to be mediated by connective tissue formation. Two clinical trials were conducted to evaluate the safety and effect of transforming growth factor-beta(2) purified from bovine bone and delivered topically to venous stasis ulcers three times per week for up to 6 weeks by means of a lyophilized collagen vehicle. The first was an open-label trial comparing transforming growth factor-beta(2) purified from bovine bone (0.5 microg/cm(2)) with a placebo consisting of lyophilized collagen vehicle-without active drug. After no safety issues arose in that trial, a prospectively randomized, closed-label, observer-blinded, three-armed trial was conducted to compare bovine transforming growth factor-beta(2) (2.5 microg/cm(2)) with the collagen matrix placebo vehicle and with a standard dressing. Standardized elastic compression was applied to all test extremities. The rate of reduction of ulcer area as measured by planimetry was the primary measure of effect. No serious safety-related events occurred in either trial. Clinical evaluation suggested that improvement in the quality and quantity of granulation tissue appeared to precede epithelialization of ulcers treated with bovine transforming growth factor-beta(2). In both studies, treatment with bovine transforming growth factor-beta(2) appeared to have a positive effect on the rate of ulcer closure, whereas ulcers in the control groups continued to exhibit impaired healing. In the open-label study, the mean rate of closure of ulcers treated with bovine transforming growth factor-beta(2) was significantly greater than that of ulcers treated with placebo. There was likewise enhanced reduction in ulcer area in the ulcers treated with bovine transforming growth factor-beta(2) in the second trial. However, because of a higher variability in patient response and a greater placebo effect, the difference was not significant. The placebo was not worse than the standard care arm, thereby showing that the vehicle is not injurious to healing. The combined results of the two trials suggest that, at doses of 0.5 to 2.5 microg/cm(2), bovine transforming growth factor-beta(2) is safe as a topically applied agent in a collagen matrix vehicle and can have a positive effect on closure of venous stasis ulcers. Large multicenter trials appear to be indicated to evaluate fully the potential utility of transforming growth factor-beta(2) in accelerating closure of chronic dermal ulcers.

Novel spacer device does not improve adherence in childhood asthma

The Funhaler (FH) is a novel spacer device (holding chamber) that has been designed to improve adherence and aerosol delivery in young asthmatic children using a metered dose inhaler. A pilot study reported a 38% increase in parent-reported adherence over 2 weeks compared with the child's normal spacer. The aim of this study was to investigate whether the FH would be associated with superior adherence in the medium term (3 months) using an objective assessment. Forty-seven children aged 18 months to 7 years were randomised to a FH or control small volume spacer. Participants were reviewed monthly for 3 months. Adherence was measured using an electronic monitoring device (Smartinhaler). Disease control was based on symptom scores and exacerbation rates. Twenty-six children were randomised to the FH and 21 to the control spacer. Three children withdrew (FH = 2). Median adherence each month for the 3 months was 74%, 54%, and 46% for the FH and 70%, 73%, and 54% for the control spacer. The difference in adherence was not statistically significant (P = 0.47, 0.37, and 0.23, respectively). There was also no significant difference in exacerbation rates or symptom scores. Seven of the FHs broke during the study. The FH was preferred by 21/24 parents randomised to the FH compared with their child's normal spacer. Despite the FH being popular with children and parents its use was not associated with improved adherence or disease control.

Detection of central respiratory events using pulse transit time in infants

The prevalence of sudden infant death syndrome (SIDS) has been well studied and central sleep apnea is deemed as one of the possible causes. Current gold standard for its diagnosis is nocturnal polysomnography (PSG). However, this procedure is complex and generally needs to be performed in a sleep laboratory. Pulse transit time (PTT) shows its potential to indicate abrupt blood pressure (BP) changes during the occurrences of upper airway obstruction. The main objective of this study was to assess the capability of PTT to differentiate central respiratory events from tidal breathing in infants. This study involved 5 infants (4 male) with mean age of 7.8 months. 50 valid central respiratory events were randomly selected. These events were free from motion artifacts and pre-scored in the corresponding PSG studies by two blinded observers. PTT measurements from these events were then evaluated against the PSG scorings. Using a two-tailed F-test for variance, it was observed that central events differed from tidal breathing in a significant manner (p<0.05). Furthermore, PTT has showed its sensitivity to monitor marginal BP fluctuations during tidal breathing. Hence, the results herein suggest that PTT can be a valuable non-invasive technique to monitor central apneic events in sleeping infants.

Use of regression equation of peripheral pulse timing characteristics to predict hypertension in children

Studies have shown that an increase in arterial stiffening can indicate the presence of cardiovascular diseases like hypertension. Current gold standard in clinical practice is by measuring the blood pressure of patients using a mercury sphygmomanometer. However, the nature of this technique is not suitable for prolonged monitoring. It has been established that pulse wave velocity is a direct measure of arterial stiffening. However, its usefulness is hampered by the absence of techniques to estimate it non-invasively. Pulse transit time (PTT) is a simple and non-intrusive method derived from pulse wave velocity. It has shown its capability in childhood respiratory sleep studies. Recently, regression equations that can predict PTT values for healthy Caucasian children were formulated. However, its usefulness to identify hypertensive children based on mean PTT values has not been investigated. This was a continual study where 3 more Caucasian male children with known clinical hypertension were recruited. Results indicated that the PTT predictive equations are able to identify hypertensive children from their normal counterparts in a significant manner (p<0.05). Hence, PTT can be a useful diagnostic tool in identifying hypertension in children and shows potential to be a non-invasive continual monitor for arterial stiffening.

Relations between Physiologic Parameters and Pulse Transit Time during Loaded Breathing

Pulse transit time (PTT) is a non-invasive measure, defined as time taken for the pulse pressure waves to travel from the R-wave of electrocardiogram to a selected peripheral site. Baseline PTT value is known to be influenced by physiologic variables like heart rate (HR), blood pressure (BP) and arterial compliance (AC). However, few quantitative data are available describing the factors which can influence PTT measurements in a child during breathing. The aim of this study was to investigate the effects of changes in breathing efforts on PTT baseline and fluctuations. Two different inspiratory resistive loading (IRL) devices were used to simulate loaded breathing in order to induce these effects. It is known that HR can influence the normative PTT value however the effect of HR variability (HRV) is not well-studied. Two groups of 3 healthy children (&#8804;12years) were recruited; one group with insignificant (p>0.05) HR changes during all test activities. Results showed that HRV is not the sole contributor to PTT variations and suggest that changes in other physiologic parameters are also equally important. Hence, monitoring PTT measurement can be indicative of these associated changes during tidal or increased breathing efforts in healthy children.

Body fat and circulating leukocytes in children

OBJECTIVE

To determine the effects of obesity on baseline levels of circulating granulocytes, monocytes, and lymphocyte subtypes in otherwise healthy children.

DESIGN

Two group comparison of leukocytes in normal weight control and overweight children.

SUBJECTS

In total, 38 boys and girls, ages 6-18 years, divided in two groups: normal weight, (NW, BMI<85th %tile, n=15) and overweight (OW, body mass index (BMI)>85th %tile, n=23).

MEASUREMENTS

BMI obtained from direct measures of height and body mass. Body fat was assessed by DEXA. Complete blood counts (CBC) were obtained by standard clinical hematology methods and surface antigen staining by flow cytometry.

RESULTS

The OW group compared to the NW group had increased total leukocytes counts (P=0.011), neutrophils (P=0.006), monocytes (P=0.008), total T (CD3) lymphocytes (P=0.022), and Helper T (CD4(+)) cells (P=0.003). Significant correlations were evident between leukocytes, and BMI percentile, BMI, or percent body fat. Neither lean body mass nor VO(2peak) per unit lean body mass were significantly related to any of the leukocytes. Percent body fat and BMI percentile were positively correlated (P<0.05) to total T cells (CD3) and/or helper T cells (CD4(+)).

CONCLUSION

A group of 23 overweight children displayed elevated counts in most types of circulating immune cells, suggesting the presence of low-grade systemic inflammation, a known pathogenetic mechanism underlying most long-term complications of obesity. Our data provide an additional rationale for the importance of avoiding or correcting pediatric obesity.

Do circulating leucocytes and lymphocyte subtypes increase in response to brief exercise in children with and without asthma?

BACKGROUND

Exercise can alter health in children in both beneficial (eg reduced long-term risk of atherosclerosis) and adverse (eg exercise-induced asthma) ways. The mechanisms linking exercise and health are not known, but may rest, partly, on the ability of exercise to increase circulating immune cells. Little is known about the effect of brief exercise, more reflective of naturally occurring patterns of physical activity in children, on immune cell responses.

OBJECTIVES

To determine whether (1) a 6-min bout of exercise can increase circulating inflammatory cells in healthy children and (2) the effect of brief exercise is greater in children with a history of asthma.

METHODS

Children with mild-moderate persistent asthma and age-matched controls (n = 14 in each group, mean age 13.6 years) performed a 6-min bout of cycle-ergometer exercise. Spirometry was performed at baseline and after exercise. Blood was drawn before and after exercise, leucocytes were quantified and key lymphocyte cell surface markers were assessed by flow cytometry.

RESULTS

Exercise decreased spirometry only in children with asthma, but increased (p<0.001) most types of leucocytes (eg lymphocytes (controls, mean (SD) 1210 (208) cells/microl; children with asthma, 1119 (147) cells/microl) and eosinophils (controls, 104 (22) cells/microl; children with asthma, 88 (20) cells/microl)) to the same degree in both groups. Similarly, exercise increased T helper cells (controls, 248 (60) cells/microl; children with asthma, 232 (53) cells/microl) and most other lymphocyte subtypes tested. By contrast, although basophils (16 (5) cells/microl) and CD4+ CD45RO+ RA+ lymphocytes (19 (4) cells/microl) increased in controls, no increase in these cell types was found in children with asthma.

CONCLUSIONS

Exercise increased many circulating inflammatory cells in both children with asthma and controls. Circulating inflammatory cells did increase in children with asthma, but not to a greater degree than in controls. In fact, basophils and T helper lymphocyte memory transition cells did not increase in children with asthma, whereas they did increase in controls. Even brief exercise in children and adolescents robustly mobilizes circulating immune cells.

Presence of diabetes risk factors in a large U.S. eighth-grade cohort

OBJECTIVE

The study was conducted in 12 middle schools to determine the prevalence of diabetes, pre-diabetes, and diabetes risk factors in eighth-grade students who were predominantly minority and evaluate the feasibility of collecting physical and laboratory data in schools.

RESEARCH DESIGN AND METHODS

Anthropometric measurements and fasting and 2-h post-glucose load blood draws were obtained from approximately 1,740 eighth-grade students.

RESULTS

Mean recruitment rate was 50% per school, 49% had BMI > or = 85th percentile, 40.5% had fasting glucose > or = 100 mg/dl, 0.4% had fasting glucose > or = 126 mg/dl, and 2.0% had 2-h glucose > or = 140 mg/dl and 0.1% > or = 200 mg/dl. Mean fasting insulin value was 30.1 microU/ml, 36.2% had fasting insulin > or = 30 microU/ml, and 2-h mean insulin was 102.1 microU/ml. Fasting and 2-h glucose and insulin values increased across BMI percentiles, and fasting glucose was highest in Hispanic and Native American students.

CONCLUSIONS

There was a high prevalence of risk factors for diabetes, including impaired fasting glucose (> or =100 mg/dl), hyperinsulinism suggestive of insulin resistance (fasting insulin > or = 30 microU/ml), and BMI > or = 85th percentile. These data suggest that middle schools are appropriate targets for population-based efforts to decrease overweight and diabetes risk.

Breath sulfides and pulmonary function in cystic fibrosis

We have determined the concentrations of carbonyl sulfide (OCS), dimethylsulfide, and carbon disulfide (CS(2)) in the breath of a group of cystic fibrosis (CF) patients and one of healthy controls. At the detection sensitivity in these experiments, room air always contained measurable quantities of these three gases. For each subject the inhaled room concentrations were subtracted from the time-coincident concentrations in exhaled breath air. The most significant differences between the CF and control cohorts in these breath-minus-room values were found for OCS. The control group demonstrated a net uptake of 250 +/- 20 parts-per-trillion-by-volume (pptv), whereas the CF cohort had a net uptake of 110 +/- 60 pptv (P = 0.00003). Three CF patients exhaled more OCS than they inhaled from the room. The OCS concentrations in the CF cohort were strongly correlated with pulmonary function. The dimethylsulfide concentrations in breath were greatly enhanced over ambient, but no significant difference was observed between the CF and healthy control groups. The net (breath minus room) CS(2) concentrations for individuals ranged between +180 and -100 pptv. They were slightly greater in the CF cohort (+26 +/- 38 pptv) vs. the control group (-17 +/- 15 pptv; P = 0.04). Lung disease in CF is accompanied by the subsistence of chronic bacterial infections. Sulfides are known to be produced by bacteria in various systems and were therefore the special target for this investigation. Our results suggest that breath sulfide content deserves attention as a noninvasive marker of respiratory colonization.

Trends in surface water chemistry of acidified UK freshwaters, 1988-2002

Analysis of water chemistry data from 15 years of monitoring at 22 acid-sensitive lakes and streams in the UK reveals coherent national chemical trends indicative of recovery from acidification. Excess sulphate and base cations exhibit significant decline, often accompanied by an increase in an alkalinity-based determination of acid neutralising capacity (AB-ANC) and, at fewer sites, a decline in hydrogen and labile aluminium. Acid neutralising capacity determined by "charge-balance" (CB-ANC) exhibits few trends, possibly due to compound errors associated with its determination. Trend slopes in excess sulphate correlate with those for base cations, hydrogen ion and AB-ANC, with between-site variability linked to catchment hydrology, sea-salt inputs and forestry. Nitrate concentrations have not changed significantly but show high sensitivity to varying climate. Trends in AB-ANC are influenced by significant increases in dissolved organic carbon, the cause of which it is vital to establish before trends in the former can definitively be attributed to decreasing acidic deposition.

Long-term increases in surface water dissolved organic carbon: observations, possible causes and environmental impacts

Dissolved organic carbon (DOC) concentrations in 22 UK upland waters have increased by an average of 91% during the last 15 years. Increases have also occurred elsewhere in the UK, northern Europe and North America. A range of potential drivers of these trends are considered, including temperature, rainfall, acid deposition, land-use, nitrogen and CO2 enrichment. From examination of recent environmental changes, spatial patterns in observed trends, and analysis of time series, it is suggested that DOC may be increasing in response to a combination of declining acid deposition and rising temperatures; however it is difficult to isolate mechanisms based on monitoring data alone. Long-term DOC increases may have wide-ranging impacts on freshwater biota, drinking water quality, coastal marine ecosystems and upland carbon balances. Full understanding of the significance of these increases requires further knowledge of the extent of natural long-term variability, and of the natural "reference" state of these systems.

Evidence of sulphur and nitrogen deposition signals at the United Kingdom Acid Waters Monitoring Network sites

Some recent studies of trends in sulphate in surface waters have alluded to possible lag effects imposed by catchment soils, resulting in discrepancies between trends in deposition and run-off. To assess the extent of these possible effects in the UK, sulphate concentration data from the United Kingdom Acid Waters Monitoring Network (AWMN) sites are compared with estimates of sulphur deposition at each site. From these data, input-output budgets are computed at an annual time scale. The estimated budgets suggest a close association between catchment sulphur inputs and outputs at an annual scale, with well-balanced annual budgets at most sites, indicative of only minor lag effects. A similar analysis of the AWMN site nitrogen budget shows little evidence of an association between nitrogen inputs and outputs at this time scale.

Motion artefact reduction of the photoplethysmographic signal in pulse transit time measurement

Motion artefact is a common occurrence that contaminates photoplethysmographic (PPG) measurements. To extract timing information from signals during artefact is challenging. PPG signal is very sensitive to artefacts and can be used in applications like, pulse transit time (PTT) as part of the polysomnographic studies. A correlation cancellation or signal processing approach is implemented with the adaptive cancelling filter concept and a triaxial accelerometry. PPG signals obtained from a Masimo (Reference) pulse oximeter is used as reference to compare with the reconstructed PPG signals. Different hands are used for each PPG source, one stationary while the other involves typical movements during sleep. A second Masimo pulse oximeter is used to register intensity of timing errors on commercial PPG signals. 108 PTT measurements are recorded in three different movements with PTT estimates from unprocessed PPG signals showing 35.51+/-27.42%, Masimo 50.02+/-29.40% and reconstructed 4.32+/-3.59% difference against those from the Reference PPG. The triaxial accelerometry can be used to detect the presence of artefact on PPG signals. This is useful in PTT measurements when signal contaminated with artefacts are required for further analysis, especially after and during arousals in sleep. The suggested filtering model can then reconstruct these corrupted PPG signals.

IL-6-induced skeletal muscle atrophy

Chronic, low-level elevation of circulating interleukin (IL)-6 is observed in disease states as well as in many outwardly healthy elderly individuals. Increased plasma IL-6 is also observed after intense, prolonged exercise. In the context of skeletal muscle, IL-6 has variously been reported to regulate carbohydrate and lipid metabolism, increase satellite cell proliferation, or cause muscle wasting. In the present study, we used a rodent local infusion model to deliver modest levels of IL-6, comparable to that present after exercise or with chronic low-level inflammation in the elderly, directly into a single target muscle in vivo. The aim of this study was to examine the direct effects of IL-6 on skeletal muscle in the absence of systemic changes in this cytokine. Data included cellular and molecular markers of cytokine and growth factor signaling (phosphorylation and mRNA content) as well as measurements to detect muscle atrophy. IL-6 infusion resulted in muscle atrophy characterized by a preferential loss of myofibrillar protein (-17%). IL-6 induced a decrease in the phosphorylation of ribosomal S6 kinase (-60%) and STAT5 (-33%), whereas that of STAT3 was increased approximately twofold. The changes seen in the IL-6-infused muscles suggest alterations in the balance of growth factor-related signaling in favor of a more catabolic profile. This suggests that downregulation of growth factor-mediated intracellular signaling may be a mechanism contributing to the development of muscle atrophy induced by elevated IL-6.

Effect of intense wrestling exercise on leucocytes and adhesion molecules in adolescent boys

BACKGROUND

In adults, exercise is a powerful and natural stimulator of immune cells and adhesion molecules. Far less is known about exercise responses during childhood and adolescence and whether or not exercise in "real life" activities of healthy adolescents influences immune responses.

OBJECTIVE

To determine if strenuous exercise leads to significant changes in leucocyte number and adhesion molecule expression in adolescent boys.

METHODS

Eleven healthy, high school boys, aged 14-18.5 years, performed a single, typical, 1.5 hour wrestling practice session. Blood was sampled before and after the session. Flow cytometry was used to evaluate changes in immune responses.

RESULTS

The exercise led to significant (p<0.05) and robust increases in granulocytes, monocytes, and all lymphocyte subpopulations. The most significant changes were observed for natural killer cells (p<0.0005). The number of T cytotoxic and T helper cells expressing CD62L increased significantly (p<0.002 and p<0.0005 respectively), as did the number of T cytotoxic and T helper cells not expressing CD62L (p<0.003 and p<0.009 respectively). The density of CD62L on lymphocytes decreased significantly with exercise (p<0.0005), whereas CD11a (p<0.01) and CD54 (p<0.01) increased.

CONCLUSIONS

The data show that an intense wrestling bout in adolescent boys leads to profound stimulation of the immune system. The role of these common changes in overall immune status and the development of the immune and haemopoietic systems has yet to be determined.

Phosphorus in soils and field drainage water in the Thame catchment, UK

Field drains were sampled at five farms in a catchment in south-central England. The farms were selected to include the main soil types present in the catchment, stagnogleys and pelosols. The phosphorus content of field drainage water was measured on several occasions from 1999 to 2000, under varying flow conditions. The components measured were soluble reactive phosphorus (SRP), total dissolved phosphorus (TDP) and total phosphorus (TP). SRP concentrations in drainage water were lower than in streams in the catchment which had no apparent point source. This indicated that many streams were receiving unidentified point sources of SRP. Measurements of P in field drainage water samples under high flow conditions showed concentrations of particulate phosphorus and SRP up to 1300 and 300 microg l(-1), respectively, these being associated with high suspended sediment concentrations. Comparison of field drain and soil phosphorus contents at the locations sampled did not provide evidence of an inter-relationship. The equilibrium phosphorus content (EPC0) of surface soil was generally higher than the SRP content of drainage water, at one farm by 1 order of magnitude. The variability in measurements suggested a larger-scale and more focussed survey would be required to characterise catchment-scale phosphorus losses from commercial farms by land use and soil type.

The phosphorus budget of the Thame catchment, Oxfordshire: 2. Modelling

The phosphorus budget of the River Thame was modelled at a daily time scale, using estimates of diffuse and point source contributions of discharge. The model simulated suspended sediment (SS), soluble unreactive phosphorus (SUP), soluble reactive phosphorus (SRP) and particulate phosphorus (PP) concentrations within the main river and major tributaries. Diffuse source estimates of phosphorus loads were based on characteristic losses from identified main landscape classes, with hydrology described by a simple conceptual storage model. In-stream flow was modelled using a kinematic wave equation. Transfer of suspended sediment and phosphorus components was approximated by advection. In-stream sources and sinks included uptake and release of soluble reactive phosphorus by bed sediment, instant equilibration between SRP and the PP concentration on suspended sediment, and flow-related entrainment and deposition of suspended sediment. Simulations at sites within the catchment were compared with measurements made in 1998-1999. Results showed the P budget is dominated by mixing of diffuse and point source water, but some within-river processes have been shown to be capable of significantly influencing SRP concentrations. The development of a sediment entrainment and deposition component of the model has proved particularly valuable in emulating the hysteretic relationship between discharge and suspended sediment concentration in the river. It also provides a measure of available bed sediment.

The phosphorus budget of the Thame catchment, Oxfordshire, UK: 1. Mass balance

The relative magnitudes of annual diffuse and point source loads of phosphorus (P) to the River Thame were estimated from daily and monthly measurements of discharge and concentration. Existing data from gauging and monitoring sites on the river network and at point sources were supplemented by survey data at a range of spatial scales. Results showed that during low flow periods most of the P could be attributed to point sources, while at high flows the figure was less than 10%. The introduction of P stripping at Aylesbury, a major sewage treatment works in the catchment, was estimated to have reduced the annual load of P from the sewage treatment works by approximately 45 t, with a similar reduction in loss from the catchment. This gave a reduction in low flow concentrations of soluble reactive phosphorus (SRP) from 2.5 to 1.7 mg l(-1). Concentrations of SRP in river water remain above eutrophication thresholds because of the influence of other STWs in the catchment and insufficient natural discharge to dilute this.

A uniform extracellular stimulus triggers distinct cAMP signals in different compartments of a simple cell

cAMP, the classical second messenger, regulates many diverse cellular functions. The primary effector of cAMP signals, protein kinase A, differentially phosphorylates hundreds of cellular targets. Little is known, however, about the spatial and temporal nature of cAMP signals and their information content. Thus, it is largely unclear how cAMP, in response to different stimuli, orchestrates such a wide variety of cellular responses. Previously, we presented evidence that cAMP is produced in subcellular compartments near the plasma membrane, and that diffusion of cAMP from these compartments to the bulk cytosol is hindered. Here we report that a uniform extracellular stimulus initiates distinct cAMP signals within different cellular compartments. By using cyclic nucleotide-gated ion channels engineered as cAMP biosensors, we found that prostaglandin E(1) stimulation of human embryonic kidney cells caused a transient increase in cAMP concentration near the membrane. Interestingly, in the same time frame, the total cellular cAMP rose to a steady level. The decline in cAMP levels near the membrane was prevented by pretreatment with phosphodiesterase inhibitors. These data demonstrate that spatially and temporally distinct cAMP signals can coexist within simple cells.

Beta(2)-adrenoceptor polymorphism and body mass index are associated with adult-onset asthma in sedentary but not active women

STUDY OBJECTIVE

Beta(2)-adrenoceptor Gly16 polymorphism has been associated with asthma severity and beta(2)-adrenoceptor receptor downregulation, but not with the diagnosis of asthma. Glu27 polymorphism may limit beta(2)-adrenoceptor downregulation and predict body mass index (BMI), particularly among sedentary persons. In addition, BMI predicts asthma. We hypothesized that these DNA sequence variants predict adult-onset asthma only in sedentary women.

DESIGN

Nested case-control study.

SETTING

Nurses' Health Study, a large, prospective cohort study with participants throughout the United States.

PARTICIPANTS

Among lifelong nonsmokers, 171 women with adult-onset, medication-requiring asthma and 137 age-matched control subjects.

MEASUREMENTS

Physical activity and BMI were self-reported by previously validated questionnaire items. Genomic DNA was obtained from buccal brushings collected via first-class mail.

RESULTS

Of 76 sedentary women, the adjusted odds ratios of Gly16 allele were 7.4 (p = 0.047) for asthma and 13.8 (p = 0.02) for steroid-requiring asthma. No similar associations were observed among 232 active women (p = 0.91). Sedentary individuals with both Gly16 and Glu27 alleles had a less elevated risk for asthma. BMI was associated with asthma and Glu27 allele among sedentary women.

CONCLUSION

This exploratory analysis suggests an important gene/environment interaction for asthma involving physical activity level. Further study in larger populations is warranted to confirm if sedentary lifestyle unmasks a genetic risk for asthma.

Flow-independent nitric oxide exchange parameters in healthy adults

Currently accepted techniques utilize the plateau concentration of nitric oxide (NO) at a constant exhalation flow rate to characterize NO exchange, which cannot sufficiently distinguish airway and alveolar sources. Using nonlinear least squares regression and a two-compartment model, we recently described a new technique (Tsoukias et al. J Appl Physiol 91: 477-487, 2001), which utilizes a preexpiratory breath hold followed by a decreasing flow rate maneuver, to estimate three flow-independent NO parameters: maximum flux of NO from the airways (J(NO,max), pl/s), diffusing capacity of NO in the airways (D(NO,air), pl x s(-1) x ppb(-1)), and steady-state alveolar concentration (C(alv,ss), ppb). In healthy adults (n = 10), the optimal breath-hold time was 20 s, and the mean (95% intramaneuver, intrasubject, and intrapopulation confidence interval) J(NO,max), D(NO,air), and C(alv,ss) are 640 (26, 20, and 15%) pl/s, 4.2 (168, 87, and 37%) pl x s(-1) x ppb(-1), and 2.5 (81, 59, and 21%) ppb, respectively. J(NO,max) can be estimated with the greatest certainty, and the variability of all the parameters within the population of healthy adults is significant. There is no correlation between the flow-independent NO parameters and forced vital capacity or the ratio of forced expiratory volume in 1 s to forced vital capacity. With the use of these parameters, the two-compartment model can accurately predict experimentally measured plateau NO concentrations at a constant flow rate. We conclude that this new technique is simple to perform and can simultaneously characterize airway and alveolar NO exchange in healthy adults with the use of a single breathing maneuver.

Effects of laboratory versus field exercise on leukocyte subsets and cell adhesion molecule expression in children

In adults, exercise is a powerful and natural stimulator of immune cells and adhesion molecules. Far less is known about these exercise responses during childhood and whether or not exercise in real-life activities of healthy children might influence immune responses. We compared laboratory exercise (10 x 2 min periods of heavy, constant intensity, cycle ergcometer exercise with 1 min rests between exercise in nine subjects, aged 9-15 years) with field exercise (90 min soccer practice in nine different subjects, aged 9-11 years). Blood was sampled before both protocols, 5 min after the 30 min laboratory protocol, and 10-15 min after the 90 min field protocol. Both field and laboratory exercise protocols led to significant (P<0.05) increases in granulocytes, monocytes, and all lymphocyte subpopulations. The mean (SEM) increases were similar for the two protocols except for the significantly greater increase in laboratory compared with field protocols for natural killer cells [142 (39)% vs 12 (16)%, P<0.001] and monocytes [64 (22)% vs 32 (19)%, P<0.001] Both protocols significantly influenced adhesion molecules (such as CD54) which have not been previously studied in children. However, the adhesion molecule CD8+ CD62L increased to a significantly (P < 0.001) greater extent in the laboratory [101 (25)%] versus field [34 (25)%] protocol. Finally, the density of CD632L on lymphocytes significantly decreased with laboratory exercise but showed no change in the field protocol [-20 (3)% vs -3 (3)%, P<0.001]. The rapid and substantial immune response in both laboratory and field protocols suggests that exercise stimulation of the immune system occurs commonly in the real lives of children and may play a role in their overall immune status.

Fitness, acute exercise, and anabolic and catabolic mediators in cystic fibrosis

Exercise can stimulate catabolic inflammatory cytokines even in healthy children. For patients with cystic fibrosis (CF), this may be problematic because CF is characterized by increased inflammation and suppressed growth. We examined fitness and the response to brief exercise of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), insulinlike growth factor-I (IGF-I), and IGF binding protein-1 (IGFBP-1) in 14 subjects with CF (10.5 +/- 0.8 yr of age), 9 of whom were treated with ibuprofen, and 14 healthy control subjects (11.6 +/- 0.5 yr of age, NS). Subjects performed brief intermittent, constant work rate protocol (scaled to each individual's exercise capacity) with blood and urine sampling. Peak V O(2) was correlated with IGF-I (r = 0.68, p < 0.01) in control subjects but not in subjects with CF. In subjects with CF, baseline IL-6 was 79% greater (p < 0.05) and IGF-I was 47% lower than in control subjects (p < 0.05). Post hoc analysis revealed a progressive increase in the IL-6 response to exercise, with the lowest increase observed in control subjects (11.8 +/- 4.6 pg/L/kJ), higher increases in patients with CF treated with ibuprofen (23.4 +/- 7.7 pg/L/kJ), and highest in subjects with CF not receiving ibuprofen (29.2 +/- 7.5 pg/L/kJ). Qualitatively similar results were observed for TNF-alpha. Exercise also significantly increased IGFBP-1 in both control subjects and subjects with CF. Brief exercise can increase even chronically elevated inflammatory mediators in CF, and this response may be attenuated by ibuprofen.

Plastic bronchitis and the role of bronchoscopy in the acute chest syndrome of sickle cell disease

STUDY OBJECTIVES

To review the prevalence, clinical features, and role of bronchoscopy in patients with plastic bronchitis during the acute chest syndrome (ACS) of sickle cell disease (SCD).

DESIGN

Eight-year review of clinical experience.

SETTING

Tertiary referral children's hospital.

PATIENTS

Twenty-six pediatric inpatients with 29 ACS episodes requiring diagnostic bronchoscopy.

RESULTS

Of the pediatric inpatients with ACS who underwent bronchoscopy, plastic bronchitis was diagnosed in 21 of 29 episodes (72%). There was no difference in clinical features between the patients with and without plastic bronchitis. Bronchoscopy was an essential diagnostic tool, but its therapeutic benefits were doubtful.

CONCLUSIONS

This is the first report of the prevalence of plastic bronchitis in patients with ACS of SCD. In our patient population, this condition was found to be common. The role of diagnostic bronchoscopy is essential. A large series, multicenter study is required to determine whether bronchoscopy and BAL are therapeutically beneficial when added to currently practiced supportive care.

Adenovirus encoded cyclic nucleotide-gated channels: a new methodology for monitoring cAMP in living cells

The current, static methodologies for measuring cyclic AMP (cAMP) may underestimate its regulatory properties. Here, we have exploited the Ca2+-conducting properties of cyclic nucleotide-gated (CNG) channels to measure cAMP in live cells, in response to various stimuli. We placed a mutated CNG channel with high sensitivity to cAMP in adenovirus to maximize and render facile its expression in numerous cell types. The ready, continuous nature of the readout contrasted with the traditional approach, which yielded similar static information, but lacked any continuous or interactive qualities. It seems fair to predict that this readily adopted approach will broaden the perception of cAMP signaling.

Fitness, training, and the growth hormone-->insulin-like growth factor I axis in prepubertal girls

We recently demonstrated that a brief endurance type training program led to increases in thigh muscle mass and peak oxygen uptake (VO(2)) in prepubertal girls. In this study, we examined the effect of training on the GH-->insulin-like growth factor I (GH-->IGF-I) axis, a system known to be involved both in the process of growth and development and in the response to exercise. Healthy girls (mean age 9.17 +/- 0.10 yr old) volunteered for the study and were randomized to control (n = 20) and training groups (n = 19) for 5 weeks. Peak VO(2), thigh muscle volume, and blood samples [for IGF-I, IGF-binding proteins (IGFBP)-1 to -6, and GHBP] were measured. At baseline, IGF-I was significantly correlated with both peak VO(2) (r = 0.44, P < 0.02) and muscle volume (r = 0.58, P < 0.004). IGFBP-1 was negatively correlated with muscle volume (r = -0.71, P < 0.0001), as was IGFBP-2. IGFBP-4 and -5 were significantly correlated with muscle volume. We found a threshold value of body mass index percentile (by age) of about 71, above which systematic changes in GHBP, IGFBP-1, and peak VO(2) per kilogram were noted, suggesting decreases in the following: 1) GH function, 2) insulin sensitivity, and 3) fitness. Following the training intervention, IGF-I increased in control (19.4 +/- 9.6%, P < 0.05) but not trained subjects, and both IGFBP-3 and GHBP decreased in the training group (-4.2 +/- 3.1% and -9.9 +/- 3.8%, respectively, P < 0.05). Fitness in prepubertal girls is associated with an activated GH-->IGF-I axis, but, paradoxically, early in a training program, children first pass through what appears to be a neuroendocrine state more consistent with catabolism.

Antinociceptive activity of and clinical experience with buprenorphine in swine

We performed antinociceptive testing on swine receiving buprenorphine. Intravenous access was achieved, and animals were allowed to recover for 24 h. Baseline skin-twitch latency to a focused light source was determined for each animal. Animals received intravenous (i.v.) buprenorphine at 0.08 (n =1), 0.16 (n = 1), 0.005 (n = 5), 0.01 (n = 5), or 0.02 mg/kg (n = 6). Skin-twitch latency was determined 15, 30, 60, 120, 180, 240, 300, 360, 420, 480, 540, and 600 min after buprenorphine administration. Analgesic activity as measured by a significant increase in latency time over baseline values occurred at all time points except 480 min in animals that received 0.02 mg/kg buprenorphine i.v. Analgesic activity to 420 min was demonstrated in animals that received 0.01 mg/kg buprenorphine i.v. Analgesic activity was not demonstrated at any time point in animals that received 0.005 mg/kg buprenorphine i.v. A retrospective analysis of postoperative care records was performed to determine whether 0.01 mg/kg buprenorphine i.v. or intramuscularly (i.m.) postoperatively to swine provided clinically relevant analgesia. Records of swine receiving buprenorphine from 1997 to 2000 were reviewed for indications of treatment failure, such as pain or a change in analgesic regimen from that used routinely. Treatment failure occurred in 18 of 416 (4.3%) cases treated with buprenorphine. This failure occurred in 17% of cases with problems categorized as inflammatory in nature and in 15.5% of those with systemic problems or organ failure. We concluded that antinociceptive testing predicted that buprenorphine administered at 0.01 mg/kg i.v. in swine likely would provide analgesic efficacy for 6 h and when administered at 0.02 mg/kg i.v. likely would provide 10 h analgesia. Clinical signs of pain in animals recovering from surgery were not observed in the majority of cases when buprenorphine was administered twice or thrice daily at 0.01 mg/kg i.m. or i.v. However, buprenorphine was less effective at treating signs of pain associated with inflammation, organ failure, or systemic disease than at ameliorating pain associated with surgical incisions and orthopedic, dental, and ophthalmic procedures.

Burkholderia cepacia in cystic fibrosis: novel Australian cluster strain without accelerated respiratory deterioration

OBJECTIVE

To determine whether 4 years of colonization with a novel Australian cluster strain (The 'Hunter' strain) of Burkholderia cepacia (B. cepacia) in cystic fibrosis (CF) patients was associated with more rapid decline in nutritional status and pulmonary function than in non-colonized contemporaries from the same CF clinic.

METHODOLOGY

A retrospective review of respiratory function and nutritional data from a single multidisciplinary paediatric CF clinic over 4 years (1993-97).

RESULTS

Paired spirometry data for 1993 and 1997 were available in 47 patients without (n = 31) and with B. cepacia (n = 16) colonization (mean (+/- SD) ages in 1993: 12.1 years +/- 4.0 vs 12.6 years +/- 6.5; P = 0.83). Their percentage predicted forced expiratory volume in 1 s (FEV1) (94.2% +/- 16.7 vs 85.9% +/- 21.2; P = 0.19) were not significantly different. The averaged annual fall in FEV1 over 4 years was also not significantly different (3.8% +/- 3.8 vs 3.6% +/- 3.7; P = 0.82). Weight percentile (Wt%), height percentile (Ht%) and percentage age weight for height (%WFH) were not significantly different between groups in 1993. By 1997, Wt% (36.7% +/- 25.1 vs 22.3% +/- 19.6; P = 0.04) and Ht% (42.5% +/- 29.6 vs 17.6% +/- 19.4; P = 0.002) but not %WFH (102% +/- 10.0 vs 106% +/- 11.2; P > 0.10) were lower in subjects with B. cepacia.

CONCLUSIONS

In adolescent CF patients, colonization with the Hunter strain of B. cepacia was associated with a deterioration in some nutritional parameters but not with an accelerated decline in FEV1 over 4 years. As varying pathogenicity of B. cepacia strains may account for differing rates of pulmonary decline, further assessment of the consequences of colonization with certain strains of B. cepacia in CF is needed.

Oxidative Stress in Cystic Fibrosis: Dietary and Metabolic Factors

OBJECTIVE

To examine oxidative stress in CF by measuring 8-iso-PGF2alpha and antioxidant defenses, in relation to dietary intake, immune function and clinical status.

METHODS

We measured total plasma concentrations of 8-iso-PGF2alpha and dietary antioxidants (vitamin E, vitamin C, beta-carotene), erythrocyte antioxidant enzyme activities (glutathione peroxidase and superoxide dismutase), lung function and dietary intake in 21 CF subjects and 21 healthy age- and gender-matched controls.

RESULTS

Total plasma 8-iso-PGF2alpha concentration (median [quartile 1-quartile 3]) was significantly higher in CF subjects compared to controls (214 pg/mL (155-331) vs. 135 pg/mL (101-168), p = 0.001). Neutrophil, monocyte and total white cell counts were elevated in the CF group and these correlated with 8-iso-PGF2alpha concentration. Despite similar dietary intake, lower plasma antioxidant concentrations were observed in the CF group (vitamin E, p < 0.001, vitamin C, p = 0.004, beta-carotene, p = 0.001). 8-iso-PGF2alpha correlated negatively with plasma vitamin E, C and beta-carotene concentrations.

CONCLUSION

Oxidative stress is increased in CF patients, despite normal dietary antioxidant intake. The immune response appears to be a key factor causing oxidative stress. Antioxidant intervention aimed at reducing oxidative stress in CF needs to be assessed.

Persistent interactions between the two transmembrane clusters dictate the targeting and functional assembly of adenylyl cyclase

Adenylyl cyclases possess complex structures like those of the ATP binding cassette (ABC) transporter family, which includes the cystic fibrosis transmembrane regulator, the P-glycoprotein, and ATP-sensitive K(+) channels [1-4]. These structures comprise a cytosolic N terminus followed by two tandem six-transmembrane cassettes, each associated with a highly homologous (ATP binding) cytosolic loop [5-8]. The catalytic domains, which are located in the two large cytoplasmic loops, are highly conserved and well studied. The crystal structure of these domains has even been described recently [9, 10]. However, nothing is known of the function or organization of the 12 transmembrane segments. In the present study we adopted a range of strategies including live-cell fluorescence resonance energy transfer (FRET) microscopy, coimmunoprecipitation, and functional assays of various truncated and substituted, fluorescently-tagged molecules to analyze the trafficking and activity of this molecule. When expressed as individual peptides, the two transmembrane domains - largely independently of any cytosolic region - formed a tight complex that was delivered to the plasma membrane. This cooperation between the two intact transmembrane domains was essential and sufficient to target the enzyme to the plasma membrane of the cell. The extracellular loop between the ninth and tenth transmembrane segments, which contains an N-glycosylation site, was also necessary. Furthermore, the interaction between the two transmembrane clusters played a critical role in bringing together the cytosolic catalytic domains to express functional adenylyl cyclase activity in the intact cell.

Effect of polymorphism of the beta(2)-adrenergic receptor on response to regular use of albuterol in asthma

BACKGROUND

Regular use of inhaled beta-adrenergic agonists may have adverse effects in some asthma patients. Polymorphisms of the beta(2)-adrenergic receptor (beta(2)-AR) can affect its regulation; however, results of smaller studies of the effects of such polymorphisms on response to beta-agonist therapy have been inconsistent.

METHODS

We examined the possible effects of polymorphisms at codons 16 (beta(2)-AR-16) and 27 (beta(2)-AR-27) on response to albuterol by genotyping 190 asthmatics who had participated in a trial of regular versus as-needed albuterol use.

RESULTS

During the 16-week treatment period, patients homozygous for arginine (Arg/Arg) at beta(2)-AR-16 who used albuterol regularly had a small decline in morning peak expiratory flow (AM PEF). This effect was magnified during a 4-week run-out period, when all patients returned to as-needed albuterol only. By the end of the study, Arg/Arg subjects who had used albuterol regularly had an AM PEF 30.5 +/- 12.1 liters/min lower (p = 0.012) than Arg/Arg patients who had used albuterol as needed only. Subjects homozygous for glycine at beta(2)-AR-16 showed no such decline. Evening PEF also declined in the Arg/Arg regular but not in as-need albuterol users. No significant differences between regular and as-needed treatment were associated with polymorphisms at beta(2)-AR-27.

CONCLUSIONS

Polymorphisms of the beta(2)-AR may influence airway responses to regular inhaled beta-agonist treatment.

Training, muscle volume, and energy expenditure in nonobese American girls

Little is known about the relationship among training, energy expenditure, muscle volume, and fitness in prepubertal girls. Because physical activity is high in prepubertal children, we hypothesized that there would be no effect of training. Forty pre- and early pubertal (mean age 9.1 +/- 0.1 yr) nonobese girls enrolled in a 5 day/wk summer school program for 5 wk and were randomized to control (n = 20) or training groups (n = 20; 1.5 h/day, endurance-type exercise). Total energy expenditure (TEE) was measured using doubly labeled water, thigh muscle volume using magnetic resonance imaging, and peak O(2) uptake (VO(2 peak)) using cycle ergometry. TEE was significantly greater (17%, P < 0.02) in the training girls. Training increased thigh muscle volume (+4.3 +/- 0.9%, P < 0.005) and VO(2 peak) (+9.5 +/- 6%, P < 0.05), effects surprisingly similar to those observed in adolescent girls using the same protocol (Eliakim A, Barstow TJ, Brasel JA, Ajie H, Lee W-NP, Renslo R, Berman N, and Cooper DM, J Pediatr 129: 537-543, 1996). We further compared these two sample populations: thigh muscle volume per weight was much lower in adolescent compared with prepubertal girls (17.0 +/- 0.3 vs. 27.8 +/- 0.6 ml/kg body mass; P < 0.001), and allometric analysis revealed remarkably low scaling factors relating muscle volume (0.34 +/- 0.05, P < 0.0001), TEE (0.24 +/- 0. 06, P < 0.0004), and VO(2 peak) (0.28 +/- 0.07, P < 0.0001) to body mass in all subjects. Muscle and cardiorespiratory functions were quite responsive to brief training in prepubertal girls. Moreover, a retrospective, cross-sectional analysis suggests that increases in muscle mass and VO(2 peak) may be depressed in nonobese American girls as they mature.

Regulation of a Ca2+-sensitive adenylyl cyclase in an excitable cell. Role of voltage-gated versus capacitative Ca2+ entry

In nonexcitable cells, we had previously established that Ca(2+)-sensitive adenylyl cyclases, whether expressed endogenously or heterologously, were regulated exclusively by capacitative Ca(2+) entry (Fagan, K. A., Mahey, R. and Cooper, D. M. F. (1996) J. Biol. Chem. 271, 12438-12444; Fagan, K. A., Mons, N., and Cooper, D. M. F. (1998) J. Biol. Chem. 273, 9297-9305). Relatively little is known about how these enzymes are regulated by Ca(2+) in excitable cells, where they predominate. Furthermore, no effort has been made to determine whether the prominent voltage-gated Ca(2+) entry, which typifies excitable cells, overwhelms the effect of any capacitative Ca(2+) entry that may occur. In the present study, we placed the Ca(2+)-stimulable, adenylyl cyclase type VIII in an adenovirus vector to optimize its expression in the pituitary-derived GH(4)C(1) cell line. In these cells, a modest degree of capacitative Ca(2+) entry could be discerned in the face of a dramatic voltage-gated Ca(2+) entry. Nevertheless, both modes of Ca(2+) entry were equally efficacious at stimulating adenylyl cyclase. A striking release of Ca(2+) from intracellular stores, triggered either by ionophore or thyrotrophin-releasing hormone, was incapable of stimulating the adenylyl cyclase. It thus appears as though the intimate colocalization of adenylyl cyclase with capacitative Ca(2+) entry channels is an intrinsic property of these molecules, regardless of whether they are expressed in excitable or nonexcitable cells.