Arachidonic acid metabolites and enzyme transcripts in asthma are altered by cigarette smoking

BACKGROUND

Arachidonic acid metabolites are implicated in the pathogenesis of asthma although only limited information is available on the impact of current smoking history on these metabolites. The aim of the study was to examine the effect of smoking status on urinary, sputum, and plasma eicosanoid concentrations and relevant enzyme transcripts in asthma.

METHODS

In 108 smokers and never smokers with asthma and 45 healthy controls [smokers and never smokers], we measured urinary tetranor prostaglandin (PG)D2 (PGDM) and leukotriene (LT)E4 , induced sputum fluid LTB4 , LTE4 , PGD2 , and PGE2 , plasma secretory phospholipase A2 (sPLA2 ), and 11β prostaglandin F2α (11βPGF2α ), and, in a subgroup with severe asthma, airway leukocyte and epithelial cell mRNA expression levels of arachidonic acid metabolic enzymes.

RESULTS

Smokers with asthma had higher urinary LTE4 ; 83 (59, 130) vs 59 (40, 90) pg/mg creatinine, P = 0.008, and PGDM; 60 (35, 100) vs 41 (28, 59) ng/mg creatinine, P = 0.012 concentrations, respectively, and lower sputum PGE2 concentrations 80 (46, 157) vs 192 (91, 301) pg/ml, P = 0.001 than never smokers with asthma. Sputum LTB4 (P = 0.013), and plasma 11βPGF2α (P = 0.032), concentrations, respectively, were increased in smokers with asthma compared with healthy smokers. Asthma-specific and smoking-related increases (>1.5-fold expression) in arachidonate 15-lipoxygenase and gamma-glutamyltransferase transcripts were demonstrated.

CONCLUSIONS

Several arachidonic acid metabolites and enzyme transcripts involving both lipoxygenase and cyclooxygenase pathways are increased in smokers with asthma and differ from never smokers with asthma. Possibly targeting specific lipoxygenase and cyclooxygenase pathways that are activated by asthma and cigarette smoking may optimize therapeutic responses.

The efficacy of dantrolene sodium in controlling exertional rhabdomyolysis in the Thoroughbred racehorse

REASONS FOR PERFORMING STUDY

Dantrolene sodium (Dantrium) has been used extensively for the treatment of myopathies in man and anecdotal evidence suggests it is of clinical benefit in the control of exercise-induced rhabdomyolysis (ER) in racehorses, although data to support this are currently lacking.

OBJECTIVES

To investigate the efficacy of oral dantrolene sodium in controlling ER in a randomised, double-blind, placebo-controlled crossover trial involving 77 Thoroughbred racehorses in Newmarket, UK.

METHODS

Horses were treated on 2 occasions 1 week apart, with treatment days coinciding with a return to exercise following 2 days box rest on each occasion. For the first treatment, each horse was randomly selected to receive either 800 mg dantrolene sodium or a colour-matched placebo administered orally 1 h before exercise. This was followed by crossover to the other treatment on the second occasion, with each horse thereby acting as its own control. Degree of ER was assessed using rising serum creatine kinase (CK) levels, by subtracting pre-exercise blood CK levels from those measured in 6 h post exercise blood samples. For each horse, the difference in change between pre- and post exercise CK values between placebo and dantrolene treatments was calculated, with positive values indicating a greater rise with placebo than with dantrolene sodium treatment.

RESULTS

The overall mean difference for all horses was +104.8 iu/l and the null hypothesis, that there was no true difference in non-normally distributed post exercise rises in CK values between placebo and dantrolene treatments, was rejected (P = 0.0013) using the nonparametric Wilcoxon signed rank test. Additionally, no horses given dantrolene sodium showed clinical signs of ER, whereas 3 horses given the placebo developed ER following exercise. The incidence of ER in the study was 4% (3/77).

CONCLUSIONS

The results confirmed that oral administration of dantrolene sodium, 1 h before exercise, had a statistically significant effect on reducing the difference between pre- and post exercise plasma CK levels compared with a placebo in the same animals, and preventing clinical ER in susceptible individuals.

POTENTIAL RELEVANCE

This study suggested that dantrolene sodium is of use in controlling ER in the Thoroughbred racehorse. Further investigation into pre- and post exercise myoplasmic calcium levels and the repeat of the study late in the season when horses receive a much higher energy ration and more strenuous exercise would appear to be warranted.

Lower respiratory tract disease in Thoroughbred racehorses: analysis of endoscopic data from a UK training yard

REASON FOR PERFORMING STUDY

There has been much research directed at potential causative agents and the epidemiology of lower respiratory tract disease (LRTD), but few reports of the clinical progression and outcome.

OBJECTIVES

To define clinical features of LRTD in racehorses, including association with age and average duration of disease, through the analysis of endoscopic data.

METHODS

A retrospective analysis of records from a single training yard of endoscopic examinations undertaken over a 2-year period was performed. Horses were subjected to regular endoscopic examination for a variety of reasons, and all horses placed on antibiotic therapy for lower respiratory tract disease were rescoped following treatment. Data analysed included a 0-8 tracheal mucus score based on visible endoscopic mucus and gross tracheal lavage turbidity, as well as age and treatment duration and type.

RESULTS

A total of 522 endoscopic examinations undertaken on 123 horses and tracking 169 episodes of lower respiratory tract disease were recorded. Mean duration of disease episode was 15.5 days (median = 11 days, range = 4-61 days). Horses age 2 years were significantly more likely than those age > or=3 years to have at least one episode of respiratory disease (P<0.001). There was a direct association between initial tracheal mucus score and rescope score after treatment.

CONCLUSIONS

Lower respiratory tract disease was more common in 2-year-olds than in older horses. Affected horses had endoscopic evidence of increased tracheal mucus accumulation for an average of 15.5 days per episode, a considerably shorter period than that suggested by previous studies.

POTENTIAL RELEVANCE

Endoscopic examinations permit longitudinal tracking of lower respiratory tract disease in Thoroughbred racehorses. A prolonged duration of disease, sometimes extending for months, can be expected in a small proportion of cases, some of which appear to be refractory to treatment. There is a clear need for evidence-based analysis of treatment regimes to assist clinicians in decision making when managing disease in both individual and group situations.

Polarization Observations with the Cosmic Background Imager

Polarization observations of the cosmic microwave background with the Cosmic Background Imager from September 2002 to May 2004 provide a significant detection of the E-mode polarization and reveal an angular power spectrum of polarized emission showing peaks and valleys that are shifted in phase by half a cycle relative to those of the total intensity spectrum. This key agreement between the phase of the observed polarization spectrum and that predicted on the basis of the total intensity spectrum provides support for the standard model of cosmology, in which dark matter and dark energy are the dominant constituents, the geometry is close to flat, and primordial density fluctuations are predominantly adiabatic with a matter power spectrum commensurate with inflationary cosmological models.

The application of a scintigraphic grading system to equine tibial stress fractures: 42 cases

REASONS FOR PERFORMING STUDY

Tibial stress fractures are an important cause of lameness in the Thoroughbred racehorse. While it is recognised that these injuries can vary in clinical presentation and radiographic or scintigraphic appearance, little has been done to quantify lesion severity. By contrast the scintigraphic grading of tibial stress fractures in human athletes is widely reported and assists in the selection of appropriate management regimes.

OBJECTIVES

To determine the relationship between scintigraphic grade, clinical severity and radiographic appearance of tibial stress fractures.

METHODS

The current study involved the retrospective analysis of records from 42 Thoroughbreds with abnormal tibial scintigraphic activity.

RESULTS

There was a significant association between lesion site and scintigraphic grade and good correlation of scintigraphic scoring between investigators. No significant association was found between scintigraphic grade and either radiographic grade or degree of lameness.

CONCLUSIONS

The study confirmed that radiographic appearance is an unreliable measure of clinical severity or stage of progression of lesions. The scintigraphic grading system used in the study was not of use in defining stress fracture severity in the equine tibia.

POTENTIAL RELEVANCE

Despite this finding, there is clearly a need for prospective investigations to explore the potential for targeted management regimes for tibial injuries based on lesion site or clinical criteria.

Effect of infused angiotensin II on the bronchoconstrictor activity of inhaled endothelin-1 in asthma

STUDY OBJECTIVES

Endothelin (ET)-1 is a potent bronchoconstrictor, and asthmatics demonstrate bronchial hyperresponsiveness to ET-1 given by inhalation. Angiotensin II (Ang II) is increased in plasma in acute severe asthma, causes bronchoconstriction in asthmatics, and potentiates contractions induced by ET-1 in bovine bronchial smooth muscle in vitro, and contractions induced by methacholine both in vitro and in vivo. We wished to examine any potentiation of the bronchoconstrictor activity of inhaled ET-1 by infused Ang II at subbronchoconstrictor doses.

DESIGN

Double-blind randomized placebo-controlled study.

SETTING

Asthma research unit in university hospital.

PATIENTS

Eight asthmatic subjects with baseline FEV1 88% predicted, bronchial hyperreactivity (geometric mean, concentration of methacholine producing 20% fall, methacholine PC20 2.5 mg/mL), and mean age 37.1 years.

INTERVENTIONS

We examined the effect of subbronchoconstrictor doses of infused Ang II (1 ng/kg/min and 2 ng/kg/min) or placebo on bronchoconstrictor responses to inhaled ET-1 (dose range, 0.96 to 15.36 nmol).

MEASUREMENTS

Oxygen saturation, noninvasive BP, and spirometric measurements were made throughout the study visits. Blood was sampled for plasma Ang II levels at baseline and before and after ET-1 inhalation.

RESULTS

Ang II infusion did not produce bronchoconstriction per se at either dose prior to ET-1 challenge. Bronchial challenge with inhaled ET-1 produced dose-dependent bronchoconstriction, but there was no difference in bronchial responsiveness to ET-1 comparing infusion of placebo with Ang II at 1 ng/kg/min or 2 ng/kg/min (geometric mean, concentration of ET-1 producing 15% fall, 5.34 nmol, 4.95 nmol, and 4.96 nmol, respectively) (analysis of variance, p > 0.05). There was an increase in systolic and diastolic BP at the higher dose of Ang II compared to placebo (mean 136/86 vs 117/75 mm Hg, respectively). Plasma Ang II was elevated following infusion of both doses of Ang II compared to placebo.

CONCLUSIONS

In contrast to the potentiating effect on methacholine-induced bronchoconstriction, Ang II at subbronchoconstrictor doses does not potentiate ET-1-induced bronchoconstriction in asthma.

Fracture of the wing of the ilium, adjacent to the sacroiliac joint, in thoroughbred racehorses

During a two year period, sagittal fractures of the wing of the ilium were diagnosed in 10 Thoroughbred horses. All were spontaneous fractures sustained during normal exercise in training and racing, with no history of inciting trauma. When ultrasound scans of the surface of the pelvis were performed, the fracture was clearly visible as a discontinuity of the sacral wing of the ilium. In 3 horses, an irregular contour suggestive of periosteal callus was seen in the vicinity of the acute fracture. All horses examined by gamma scintigraphy had a focal increase in uptake of isotope just lateral to the tuber sacrale. Nine of the horses were treated conservatively by rest. The other horse had bilateral fractures and was subjected to euthanasia at the time of the injury. Six horses returned to full training, and 2 subsequently won, without recurrence of lameness.

Lung abscesses mimicking multiple pulmonary metastases

Five patients receiving chemotherapy for cancer through Hickman central venous catheters had lung lesions detected by plain chest radiography or computed tomography. In each case these were initially misdiagnosed as metastases, although they ultimately proved to be staphylococcal abscesses. Because of the grave implications of an erroneous diagnosis of metastatic malignant disease, clinicians are urged to consider abscesses in the differential diagnosis of radiological chest abnormalities in such patients.