Polymorphism of the beta2-adrenoceptor and the response to long-term beta2-agonist therapy in asthma

DNA-based diagnosis of haemophilia A has previously been carried out by linkage analysis using two highly informative markers, Hind III RFLP and St14 VNTR, for affected Turkish families. In the present study the number and frequency of the microsatellite alleles at introns 13 and 22 in the factor VIII (FVIII) gene were analysed in order to increase the rate of informative females and accuracy of linkage analysis. Six alleles were observed at both loci. The two most frequent alleles of each locus were the same as the two common alleles found in Anglo-Americans. The comparison of heterozygosity of both microsatellite loci showed that the Turkish population is slightly less polymorphic than Anglo-Americans but more polymorphic than Chinese, Slavs and Uzbekians. The additional use of the two microsatellite repeat polymorphisms with the previously established informative markers has been accepted as the most effective strategy in DNA diagnosis by linkage analysis for the assessment of haemophilia A carriers and affected fetuses in the Turkish population. The modifications adopted in this study for the multiplex PCR analysis of the microsatellite repeat polymorphism eliminated the use of radioactivity and sequencing gels, reducing cost and labour.     

Effects of beta 2-agonist administration and exercise on contractile activation of skeletal muscle fibers

Clenbuterol, a beta 2-adrenoceptor agonist, has therapeutic potential for the treatment of muscle-wasting diseases, yet its effects, especially at the single-fiber level, have not been fully characterized. Male C57BL/10 mice were allocated to three groups: Control-Treated mice were administered clenbuterol (2 mg.kg-1. day-1) via their drinking water for 15 wk; Trained-Treated mice underwent low-intensity training (unweighted swimming, 5 days/wk, 1 h/day) in addition to receiving clenbuterol; and Control mice were sedentary and untreated. Contractile characteristics were determined on membrane-permeabilized fibers from the extensor digitorum longus (EDL) and soleus muscles. Fast fibers from the EDL and soleus muscles of Treated mice exhibited decreases in Ca2+ sensitivity. Endurance exercise offset clenbuterol's effects, demonstrated by similar Ca2+ sensitivities in the Trained-Treated and Control groups. Long-term clenbuterol treatment did not affect the normalized maximal tension of fast or slow fibers but increased the proportion of fast fibers in the soleus muscle. Training increased the proportion of fibers with high and intermediate succinate dehydrogenase activity in the EDL and soleus muscles, respectively. If clenbuterol is to be used for treating muscle-wasting disorders, some form of low-intensity exercise might be encouraged such that potentially deleterious slow-to-fast fiber type transformations are minimized. Indeed, in the mouse, low-intensity exercise appears to prevent these effects.     

The occurrence of late asthmatic response to exercise after allergen challenge

OBJECTIVES: To evaluate the correlation between the pathological findings of stereotactic core needle biopsy (SCNB) and the prebiopsy mammographic findings, as well as the pathological findings of lesions that were subsequently removed by surgical excision. DESIGN: A retrospective review of 97 consecutive patients who underwent 100 SCNBs of suspicious nonpalpable mammographic lesions. The criterion standard is surgical excisional biopsy with needle localization. Mammographic findings were graded according to the American College of Radiology Breast Imaging Reporting and Data System. The pathological findings of SCNB were categorized into 4 groups: benign and specific, benign and nonspecific, premalignant, and malignant. Surgical excision of the lesion was performed if the pathological finding on SCNB was nonconcordant with the prebiopsy mammogram and when premalignant or malignant lesions were found. The pathological findings of lesions that were subsequently removed by surgical excision were compared with those of SCNB. SETTING: Community-based private multispecialty ambulatory practice. PATIENTS: A population-based sample composed of 97 patients who had grade III, IV, or V lesions on routine screening mammograms. INTERVENTION: Stereotactic core needle biopsy of nonpalpable mammographic lesions. MAIN OUTCOME MEASURES: Percentage of patients whose SCNB results were concordant with the mammographic findings and the pathological findings on subsequent surgical excision. RESULTS: Concordance between SCNB and mammography occurred in 97% of biopsy specimens. Concordance between the pathological findings of SCNB and those of surgically excised lesions occurred in 92.5% of biopsy specimens. We had 1 false-negative result. We had no false-positive diagnosis of cancer with SCNB. CONCLUSION: On the basis of accumulating literature and our own initial experience, SCNB is a promising, safe, and cost-effective procedure.     

Primary ciliary dyskinesia: diagnosis and standards of care

Primary ciliary dyskinesia (PCD) is characterized by disease of the upper and lower respiratory tract, in association with visceral mirror image arrangement in 50% of cases, due to abnormal structure and/or function of cilia. The purpose of this paper is to review the clinical features, diagnosis and management of PCD. Presentations include neonatal respiratory distress, recurrent lower respiratory tract infection, chronic rhinosinusitis and male infertility. PCD enters the differential diagnosis of bronchiectasis, atypical asthma, and unusually severe upper airway disease. Diagnosis is by a cascade of investigations, starting with the saccharin test in patients older than 10 yrs; ciliary beat frequency and pattern on light microscopy; and electron microscopy to assess ciliary morphology and orientation. It is important not to confuse primary and secondary ciliary abnormalities. Nasal nitric oxide is low in PCD, and this measurement shows promise as a screening test for PCD. Diagnosis is important, in order to prevent the development of bronchiectasis and to avoid any unnecessary otorhinolaryngological procedures. Regular follow-up is essential, and management should be multidisciplinary, with input from centres with a special interest in PCD, having access to paediatric and adult chest physicians, otolaryngologists and audiological physicians, physiotherapists, counselling services and fertility clinics. The prognosis is good, but morbidity can be considerable if PCD is incorrectly managed.     

Airway anesthesia and respiratory adaptations to dead space loading and exercise

In exercising humans, added external dead space (VD) increases minute ventilation (VI) and causes a slower and deeper breathing pattern (J. Appl. Physiol. 1991; 70:55-62). Recent studies suggest that airway receptors sensitive to topical anesthesia influence VI and breathing pattern responses to exercise and to added VD. We tested these hypotheses with a technique of airway anesthesia (Anesthesia) that has been shown to reliably attenuate airway reflexes. Anesthesia was administered by local laryngopharyngeal application and aerosolized lidocaine inhalation, and was confirmed by citric acid aerosol inhalation challenges. Twelve normal males performed maximal incremental cycle ergometer exercise on 4 d (randomized) after Anesthesia with (Anesthesia VD) and without added VD (Anesthesia Control) and after normal saline inhalation (Saline) with (Saline VD) and without added VD (Saline Control). There were no differences in the VI and breathing pattern responses during exercise between the Saline Control and the Anesthesia Control tests. After both Saline and Anesthesia inhalation, added VD resulted in an increase in VI both at rest and during exercise. At matched VI (98 L/min), the differences in tidal volume (VT) between the Saline Control and Saline VD tests (delta = 0.23 +/- 0.24 L, mean +/- SD) and the Anesthesia Control and Anesthesia VD tests (delta = 0.20 +/- 0.28 L) were not significantly different. Our study had a power of greater than 95% to detect significant differences in VI or breathing pattern due to Anesthesia. We conclude that in normal humans, airway receptors do not play a major role in ventilation and breathing pattern control during exercise, and that the respiratory adaptations to added VD during exercise are not mediated by airway afferent reflexes.     

Airway subsensitivity with long-acting beta 2-agonists. Is there cause for concern?

Regular treatment with both long- and short-acting beta 2-agonists results in tolerance to their bronchoprotective effects, although the relevance of this phenomenon in terms of long term asthma control remains unclear. However, there appears to be no appreciable difference between the 2 long-active beta 2-agonists, salmeterol and formoterol, in their propensity to induce beta 2-adrenoceptor down-regulation and subsensitivity. The degree of subsensitivity appears to be somewhat greater with indirect stimuli such as exercise and allergen challenge, compared with direct stimuli such as histamine and methacholine. This loss of functional antagonism with long-acting beta 2-agonist therapy is partial and is not prevented by concomitant inhaled corticosteroid therapy. However, the protective effects of inhaled corticosteroids on their own appear to be additive to those of long-acting beta 2-agonists when both drugs are concomitantly administered in the long term. The subsensitivity to bronchoprotection may be of clinical relevance in terms of patients who are inadvertently exposed to indirect bronchoconstrictor stimuli such as allergens or exercise, suggesting that long-acting beta 2-agonists should not be taken on a regular basis for this particular indication. There is a greater tendency for bronchodilator subsensitivity to develop with longer-acting, than with shorter-acting beta 2-agonists, and this may reflect the longer duration of beta 2-adrenoceptor occupancy and consequent downregulation. As with the bronchoprotective effects of long-acting beta 2-agonists, the development of bronchodilator subsensitivity is only partial and occurs regardless of whether patients are taking concomitant inhaled corticosteroid therapy. The long-term bronchodilator action of the long-acting beta 2-agonist itself is maintained within the twice daily administration interval. However, subsensitivity occurs in relation to a blunted response to repeated doses of short-acting beta 2-agonists, as in the setting of an acute asthma attack. There is considerable inter-individual variability in the propensity for downregulation and subsensitivity, which is determined by genetic polymorphism of the beta 2-adrenoceptor. Current international asthma management guidelines suggest that long-acting beta 2-agonists should be used on a regular basis in patients who ware inadequately controlled on inhaled corticosteroid therapy, so the addition of long-acting beta 2-agonist therapy is an alternative to using higher doses of inhaled corticosteroids. There are, however, concerns that regular long-acting beta 2-agonists might result in masking of inadequately treated inflammation in patients receiving suboptimal inhaled corticosteroid therapy. Physicians should be aware of the airway subsensitivity that develops with long-acting beta 2-agonist therapy, and patients should be warned that they may have to use higher than conventional dosages of short-acting beta 2-agonists to relieve acute bronchoconstriction in order to overcome this effect. In patients receiving an optimised maintenance dose of inhaled corticosteroid, if long-acting beta 2-agonists are to be used on an as required basis, it would seem rational to use formoterol for this purpose, due to its faster onset of action than salmeterol.     

Reduced response of the hypothalamo-pituitary-adrenal axis to alpha1-agonist stimulation during lactation

To determine whether altered noradrenergic activation of the hypothalamo-pituitary-adrenal (HPA) axis contributes to the attenuated neuroendocrine response to stress observed during lactation, the effect of intracerebroventricular injection of the alpha1-agonist methoxamine (100 microg) was compared between virgin and lactating rats. Virgin rats showed significant increases in plasma corticosterone after methoxamine, reaching 317 +/- 44 ng/ml at 10 min and remaining significantly elevated for more than 120 min, but lactating rats showed no significant increase in corticosterone levels. Furthermore, methoxamine induced an increase in paraventricular nucleus (PVN) CRF messenger RNA expression in virgin, but not lactating, animals. Both groups of rats exhibited comparable elevations in plasma PRL after methoxamine treatment. Arginine vasopressin messenger RNA expression within the parvocellular PVN was greater in the lactating animals than in the virgin controls, but methoxamine injection was without further effect. Studies performed on ovariectomized virgin rats and ovariectomized rats receiving estradiol or progesterone replacement failed to reproduce the attenuated HPA responses seen after methoxamine treatment, although methoxamine-induced PRL levels were greatly increased by estradiol, probably arising from an effect on hormone synthesis. In vitro electrophysiological recordings of PVN neurons in hypothalamic slices from proestrous virgin and lactating rats showed that 45-52% of neurons in both groups exhibited excitatory responses to 10(-4) M methoxamine, but there was a differential response to 10(-5) M methoxamine, with PVN neurons from lactating animals failing to show a response. These data show a selective down-regulation of alpha1-mediated activation of the HPA axis in lactating animals. This may contribute to the attenuated stress-induced activation of the HPA axis during lactation.     

Comparison of bronchial reactivity to ultrasonically nebulized distilled water, exercise and methacholine challenge test in asthmatic children

We studied the responses to ultrasonically nebulized distilled water (UNDW) challenge, exercise challenge and methacholine challenge in asthmatic children. Fifty-four asthmatic and fourteen nonasthmatic control children participated in this study. The UNDW inhalation test was by the methodology described by Anderson. The average output of water was approximately 3.0 mL/min (SD = .1) and inhalation times were 30 seconds, one minute, two minutes and four minutes. Some subjects performed exercise challenge on a bicycle ergometer and methacholine challenge by an Astrograph technique. Twenty-three of 54 asthmatic patients (42.6%) and none of the controls showed a fall in FEV1 greater than 20% with UNDW challenge. The fall in FEV1 with UNDW correlated with that induced by exercise challenge (r = .89) and Log Dmin, which may reflect bronchial sensitivity (r = .70). Our method is not sensitive enough for detecting bronchial hyperresponsiveness in all asthmatic children. Bronchoconstriction induced by UNDW has a similar mechanism of action as exercise and methacholine.     

Aging and immune response to exercise

Human immune function undergoes adverse changes with aging. The T cells, which have a central role in cellular immunity, show the largest age-related differences in distribution and function, with thymus involution as the apparent underlying cause. The immune responses to acute exercise and training have not been studied extensively in the elderly. The natural killer (NK) cell response to a single exercise challenge is normal in older individuals, but immediately after exercise the elderly subjects manifest less suppression of phytohemagglutinin (PHA)-induced lymphocyte proliferation than younger individuals. In contrast, a strenuous exercise seems to induce a more sustained postexercise suppression of cellular immunity in older individuals than in their young peers. A few cross-sectional comparisons of immune status between physically fit elderly individuals and young sedentary controls suggest that habitual physical activity may enhance NK cell activity, checking certain aspects of the age-related decline in T cell function, such as reduced mitogenesis in response to plant lectins and decreases in the production of certain types of cytokine. The clinical implications, however, remain to be clarified by future study.     

Airway response of horses with COPD to dry powder inhalation of ipratropium bromide

At some stages of development, it is impossible to identify the porcine nodular worms Oesophagostomum dentatum and O. quadrispinulatum to the species level using morphological parameters. A molecular approach utilizing genetic markers in the second internal transcribed spacer (ITS-2) of ribosomal (r) DNA was developed to overcome this limitation. The ITS-2 sequence of each species was determined, and specific oligonucleotide primers were designed to regions of greatest sequence difference between the species. Utilizing these primers, rapid PCR procedures were developed for the specific amplification of DNA of O. dentatum or O. quadrispinulatum, which are now used routinely to monitor the purity of larval cultures and to confirm the identity of larvae derived from the intestine or faeces. The application of specific PCR has major implications for studying the population biology of nodular worms in the pig model.     

Airway muscle in infants with congenital diaphragmatic hernia: response to treatment

BACKGROUND/PURPOSE: Airway muscle hyperactivity and chronic lung disease frequently follow congenital diaphragmatic hernia (CDH) treatment. The aim of this study was to compare the quantity of airway muscle and alveolar ductal artery muscle in CDH infants after various treatments. METHODS: Five groups were studied postmortem: CDH, died within 24 hours, without high ventilatory assistance (n = 3); CDH, various extracorporeal membrane oxgenation (ECMO) durations, without high ventilatory assistance (n = 4); CDH, various ECMO durations, with high ventilatory assistance (n = 7); no CDH, without high ventilatory assistance (n = 12); and no CDH, with high ventilatory assistance and bronchopulmonary dysplasia (BPD) (n = 5). Sections from standardized fixed lungs were immunohistochemically stained for alpha-smooth muscle actin. Muscle surrounding conducting airways from small preterminal bronchioles to bronchi was quantitated in both the ipsilateral and contralateral lungs with computerized image analysis. Similarly, muscle mass was quantitated in alveolar ductal arteries. RESULTS: CDH infants with low ventilatory assistance, regardless of postnatal age, had the same quantity of airway muscle as low ventilatory assistance controls. Infants with CDH and prolonged high ventilatory assistance had significantly more muscle throughout the conducting airways, similar to BPD infants without CDH, even though the CDH infants had significantly less exposure to high ventilatory assistance. With both low and high ventilatory assistance, the quantity of muscle in both the ipsilateral and contralateral lungs was similar. In contrast, small acinar arteries in CDH infants have increased muscle mass at birth. This muscle is decreased by ECMO but persists in CDH infants with high ventilatory assistance. CONCLUSIONS: The authors show that postnatally, CDH infants acquire increased muscle quantity throughout the conducting airways, in both the ipsilateral and contralateral lungs, with relatively short exposure to high ventilatory assistance. The normal decrease in acinar arterial mass that occurs postnatally is delayed in CDH infants with high ventilatory assistance.     

Allergen challenge of passively sensitized human bronchi alters M2 and beta2 receptor function

We investigated whether antigen challenge may alter M2 and beta2 receptor function in isolated passively sensitized human bronchi. Bronchial rings (2-4 mm internal diameter) were obtained from 12 patients. Passive sensitization was induced by serum containing high IgE levels to Dermatophagoides pteronyssinus and Dermatophagoides farinae. Rings from six patients were used to study M2 receptor function by incubating with cumulatively increasing concentrations (10(-8) M to 10(-4) M) of pilocarpine and applying electric field stimulation (EFS) at 24 Hz. The rings from the other six patients were used to study beta2 receptor function by precontracting with carbachol 10(-6) M and adding cumulatively salbutamol (10(-9) M to 10(-4) M). Additional rings from these patients were used to determine whether dysfunction occurred distal to cAMP production by precontracting with carbachol 10(-6) M and adding cumulatively theophylline (10(-9) M to 10(-4) M). The attenuation of EFS-induced force by pilocarpine and the relaxation of carbachol-precontracted rings by salbutamol were less in challenged than in control and sensitized rings. No difference between challenged, sensitized, and control rings was observed with theophylline. We conclude that allergen challenge in passively sensitized isolated human bronchial rings may result in M2 and beta2 receptor dysfunction without involving mechanisms distal to cAMP formation. It appears that products from inflammatory cells recruited from blood are not necessary for this receptor dysfunction.     

Exercise tolerance and blood pressure response to exercise testing in children and adolescents after renal transplantation

Intrauterine growth retardation (IUGR), defined as birth weight and/or length less than 3rd percentile (P) or less than-2 standard deviations (SD), concerns about 3% of newborns. About 85% born IUGR show spontaneous postnatal catch-up to a height > P3 or > -2 SD during the first two years of life. After the age of 4 year, the children without catch-up will remain short up to final height. Classical growth hormone (GH) deficiency usually does not seem responsible for the absence of catch-up in those children. A two-year GH therapy at supraphysiological doses increases growth velocity. The effect of this treatment on final height remains to be studied, as well as optimal treatment's modalities. Attention should be paid on the possible side-effects. Finally, the evaluation of the psychological impact of GH treatment will be critical.     

Treatment with antisense oligodeoxynucleotide to the opioid delta receptor selectively inhibits delta 2-agonist antinociception

Using approaches emphasizing differential antagonism of receptor selective agonists and cross-tolerance paradigms, evidence in vivo has suggested the existence of subtypes of opioid delta receptors, which have been termed delta 1 and delta 2. Recent work has elucidated the structure of an opioid delta receptor. The present investigation attempted to continue to test the hypothesis of subtypes of delta receptors and to correlate the cloned delta receptor with the existing pharmacological classification. Synthetic oligodeoxynucleotides (oligos) complementary to the 5' end of the cloned delta receptor coding region (antisense) or its corresponding sequence (sense) were given by intracerebroventricular (i.c.v.) administration to mice, twice-daily for 3 days and antinociceptive responses to selective agonists at putative delta 1 and delta 2 receptors were subsequently determined. Treatment with antisense, but not sense, oligo significantly inhibited the response to [D-Ala2,Glu4]deltorphin (delta 2 agonist), but not to [D-Pen2,D-Pen5]enkephalin (DPDPE, delta 1 agonist). Further, subsequent administration of DPDPE elicited a full antinociceptive response in the same antisense oligo treated mice which did not show a significant response to [D-Ala2,Glu4]deltorphin while antisense oligo treated mice which responded to DPDPE did not show antinociception when tested subsequently with [D-Ala2,Glu4]deltorphin. The data suggest that the cloned delta receptor corresponds to that pharmacologically classified as delta 2 and continue to support the concept of subtypes of opioid delta receptors.     

Airway hyperresponsiveness and cough-receptor sensitivity in children with recurrent cough

In children, recurrent cough is a common presenting symptom that may represent asthma. We tested the hypotheses that children with recurrent cough have increased cough-receptor sensitivity (CRS) or airway hyperresponsiveness (AHR). Skin prick testing, the capsaicin CRS test, and hypertonic saline (HS) challenge were performed in 44 children (median age: 8.9 yr) with recurrent dry cough (> or = 2 episodes of cough, each lasting > or = 2 wk, within a period of 12 mo) and 44 controls. Measures of CRS were the concentration of capsaicin required to stimulate > or = 2 coughs (Cth) and > or = 5 coughs (C5). During the coughing period, Cth (mean log: 0.62 [95% CI: 0.43 to 0.81]) and C5 (mean log: 1.15 [95% CI: 0.86 to 1.44]) of the subjects without AHR were significantly lower (p = 0.0026, 0.027, respectively) than Cth (mean log: 1.27 [95% CI: 0.88 to 1.66]) and C5 (mean log: 1.79 [95% CI: 1.21 to 2.37]) of the subjects with AHR and those of the controls (p = 0.0002 and 0.0001). During the cough-free period, there was no difference in CRS among the groups. In subjects who demonstrated AHR, the provocation dose causing a > or = 15% fall in FEV1 (PD15) during the cough period was significantly lower (p = 0.005) than that during the cough-free period. We conclude that AHR or increased CRS is present during the coughing phase in children with recurrent cough.     

Pressor response to isometric exercise in patients with multiple sclerosis

The purpose of this study was to determine whether patients with multiple sclerosis (MS) would show attenuated heart rate and/or pressor responses to isometric handgrip exercise. Patients with MS (30 males, 74 females, aged 23-61 yr) and control subjects (9 males, 16 females, aged 25-47 yr) performed isometric handgrip exercise at 30% of maximal voluntary contraction (MVC) to fatigue. Systolic, diastolic, and mean arterial pressure (MAP) increased linearly in both groups, but were significantly lower (P < 0.05) in patients with MS at 20%, 40%, 60%, 80%, and 100% of exercise duration. Mean change in MAP at fatigue was +47.9 mm Hg for controls and +28.2 mm Hg for patients with MS, with 18 patients with MS between -6 mm Hg and +15 mm Hg. Heart rate increased normally in patients with MS. To predict change in MAP at fatigue in patients with MS, stepwise regression analysis using six variables yielded an R2 of 0.26. These data suggest that in some patients MS lesions exist in areas of autonomic cardiovascular control that result in attenuated pressor responses to exercise. In 17% of patients tested, attenuation was profound. Data also suggest an abnormal dissociation between the heart rate and pressor response to static work in patients with MS.     

Hemodynamic response to exercise in dogs treated with 6-hydroxy-dopamine

A well tolerated regimen utilizing Phosphosoda and X-Prep Liquid effectively cleanses the bowel prior to x-ray examination. Good to excellent visualization was achieved in 89.3 per cent of the patients involved in the study.