Expression of PTX3, HAS2 AND TNFAIP6 genes in relation to real-time proliferation of porcine endometrial luminal epithelial cells in primary cultivation model.

Endometrial cells undergo very specific changes associated with reproductive processes. Cells prepare for embryo development by increasing their volume. Then, if fertilization fails, endometrial cells are liable for apoptosis, preparing new cells that are ready for subsequent processes related to the possibility of embryo implantation and the development of pregnancy. PTX3 and TNFAIP6 are absent or reduced in cultured COCs, resulting in a functional change in COC in vitro. In this work, we want to check how PTX3, HAS2 and TNFAIP6 behave in luminal epithelium primary cell culture. Cells obtained during slaughter from porcine specimens were cultured primarily in vitro for 7 days. Their proliferation patterns were then analysed using RTCA, with the expression of genes of interest evaluated with the use of immunofluorescence and RT-qPCR. The results of these changes in the expression of the genes of interest were analysed on each of the seven days of the porcine luminal primary cell culture. Our study showed the increased level of PTX3, HAS2 and TN¬FAIP6 expression at the same hours of primary culture. Rt-qPCR showed a higher level of expression of the PTX3 gene in the first 72 h, at the end of the lag phase (in the phase of stasis in which the cells adapt to the new environment and often die). In contrast, TNFAIP6 expression increases about 96 hours when the cells are in the full log phase (logarithmic phase growth) and continue this trend in the plateau phase. We did not observe such drastic changes in the HAS2 expression pattern, which leads us to hypothesize that PTX3 and TNFAIP6 are designed to maintain a constant level of HAS2 in the cell throughout its lifetime. The obtained results could become a point of reference for further in vivo and clinical research.

Balance between epithelial and stromal marker expression and distribution in primary culture model of porcine endometrium during real-time cell proliferation..

The similarity between humans and pigs, when it comes to tissue morphology, makes Sus scrofa not only a good research model, but also a potential source of cells for tissue engineering. Cell samples obtained from the pig donor, could be influenced in vitro, in order to become a source of tissue material for xenotransplantation, reconstructive and regenerative medicine. Significant amounts of data point to especially major similarities in pig and human reproductive systems. Because of that, particular scientific focus is centered on research concerning porcine COCs, theca and granulosa cells in primary cultures. One of the aspects of the reproductive process, that is still largely undiscovered, is the interaction between preimplantation blastocyst and maternal uterine tissues. In this study, we used molecular analysis techniques, such as RT-qPCR and immunocytochemistry, to analyze the expression and distribution of cytokeratin 18 and panCytokeratins 8, 18 and 19 and vimentin in porcine luminal endometrial epithelial cells, coupled with analysis of their behavior in RTCA. The results have confirmed the presence of epithelial, as well as stromal cell markers in the cells, varying in levels at different stages of culture. They have also given insight into the modes of proliferation and differentiation of studied cells in in vitro culture, as well as providing additional proof for the possible mesenchymal transdifferentiation of epithelial cells.

Enzyme linked receptor protein signaling pathway is one of the ontology groups that are highly up-regulated in porcine oocytes before in vitro maturation.

Before being able to fully participate in the processes associated with its function as a female gamete, the oocyte needs to undergo a range of changes to achieve its mature form. These morphological, biochemical and metabolomic processes are induced by the somatic tissues surrounding the oocyte, through the expression of specific transcription and growth factors. The maturation of the oocyte is highly important for the proceedings that lead to successful fertilization, early embryonic development and implantation. Domestic pigs were used as models for our study, with the cumulus-oocyte complexes obtained from the ovaries that were recovered at slaughter. After shedding of the cumulus, oocytes were assessed with BCB test, with the viable ones chosen to undergo in vitro maturation. With the use of expression microarrays, we analyzed gene expression before and after IVM and detected major changes in both genes that were proven to be associated with oocyte maturation before (FOS, VEGFA, CHRDL1, TGFBR3, FST, INSR, ID1, TXNIP, SMAD4, MAP3K1, EIF2AK3 and KIT) and genes not previously linked with reproduction associated processes (MYO1E, PHIP, KLF10 and SHOC2). All the genes were briefly described, with consideration of possible involvement of the newly discovered elements of the transcriptome in the process of oocyte maturation.

Modulatory effects of steroid hormones, oxytocin, arachidonic acid, forskolin and cyclic AMP on the expression of aquaporin 1 and aquaporin 5 in the porcine uterus during placentation.

Aquaporins (AQPs) are proteins forming trans-membrane channels responsible for water transport. AQP1 and AQP5 are present in structures of the female reproductive system. In the uterus, these AQPs are involved in water movement between the intraluminal, interstitial and capillary compartments and their uterine expression is essential throughout the pregnancy, including its early stages. Thus, the study aimed to assess the influence of P4 (progesterone), E2 (estradiol), OT (oxytocin), AA (arachidonic acid), cAMP and FSK (forskolin) on the AQP1 and AQP5 mRNA and protein expression in the uterine tissue of gilts on Days 30 - 32 of gestation (the placentation period), following short (3 h) and long (24 h) incubations. Steroid hormones influenced the expression of AQP1 and AQP5; E2 up-regulated, but P4 down-regulated mRNAs of these AQPs, whereas the protein level of studied AQPs was increased by both steroids. OT treatment decreased AQP1 (after 24 h), but increased AQP5 (after 3 h) mRNA expression. Treatment with AA significantly reduced the AQP1 expression at the mRNA level, but stimulated at the protein level. The expression of AQP5 mRNA and protein was stimulated by AA. FSK markedly decreased AQP1 mRNA, but increased of AQP5 after 3-h incubation. In turn, cAMP stimulated and inhibited transcription of AQP5 after 3- and 24-h incubations, respectively. Immunohistochemical analysis confirmed the uterine localization of AQP1 in the apical and basal membranes of endothelial cells and AQP5 in the apical membranes of epithelial cells under control condition. Treatments with P4, E2, AA, cAMP or FSK have caused additional appearance of AQP5 labeling in the basolateral membranes of epithelial cells. These results suggest a participation of steroid hormones (P4 and E2), AA derivatives and cAMP in controlling the expression of AQP1 and AQP5 as well as the distribution of AQP5 in the uterine tissue of pregnant gilts during placentation (Days 30 - 32 of gestation).

Expression of aquaporin 1 and 5 and their regulation by ovarian hormones, arachidonic acid, forskolin and cAMP during implantation in pigs.

Aquaporin proteins (AQPs) are a family of channels expressed in numerous mammalian tissues, where they play a fundamental role in regulating water transport across cell membranes. Based on reports that AQPs are present in the reproductive system and participate in reproductive processes, our aim was to investigate the effect of progesterone (P(4)), estradiol (E(2)), oxytocin (OT), arachidonic acid (AA), forskolin (FSK) and cyclic adenosine monophosphate (cAMP) on AQP1 and AQP5 expression at mRNA and protein levels in porcine uterine explants from Days 14-16 of gestation in order to determine if they play a role in implantation period in pigs. Quantitative real time PCR and Western-blot analysis revealed that the uterine explants treated with FSK and cAMP produce delayed, but long-term effects on AQP1 abundance (24 h) while AQP5 had a rapid and sustained response to FSK and cAMP in protein content (3 and 24 h). AA increases gene and protein content of AQP1 after longer exposition whereas AQP5 increases after 3 h only at the protein level. Both AQPs potentially remains under control of steroid hormones. OT has been shown to increase AQP1, and decrease AQP5 mRNA, without visible changes in protein content. P(4), E(2), AA, FSK and cAMP caused the appearance of AQP5 expression in the basolateral plasma membrane of the epithelial cells. The staining represents most likely AQP5 functioning mechanism for both absorption and reabsorption across the glandular epithelium.

Expression of aquaporin 1, 5 and 9 in the ovarian follicles of cycling and early pregnant pigs.

Aquaporins (AQPs) are water channel proteins responsible for water homeostasis and important for proper functioning of all body systems, including reproductive structures. This study was designed to determine their localization and quantitative changes in the pig ovary during different stages of the estrous cycle and early pregnancy. The expression of AQP 1, 5 and 9 proteins was determined by immunocytochemistry and Western blot analyses. AQP1 was found in the plasma membranes of capillary endothelium, AQP5 - in the plasma membranes of granulosa cells of developing follicles and flattened follicle cells of the primordial follicles, and AQP9 - in granulosa cells of the developing follicles. In the cyclic pigs, the expression of AQP1 and 5 proteins was the highest on Days 18-20, but did not change significantly between Days 2-4, 10-12 and 14-16 of the cycle. In pregnant pigs (Days 14-16 and 30-32), the expression of AQP1 and 5 did not change and was similar to that observed during Days 10-12 and 14-16. In turn, AQP9 expression did not change between all studied periods. In conclusion, studied AQP are localized in different cells populations, the endothelial and granulosa cells, and AQP1 and 5 seem to be crucial for follicular development in pigs.

Expression of proopiomelanocortin, proenkephalin and prodynorphin genes in porcine luteal cells.

The objective of the study was to examine the expression of the genes coding for proopiomelanocortin (POMC), proenkephalin (PENK) and prodynorphin (PDYN) in porcine luteal cells isolated from corpora lutea (CL) collected on days 3-6, 8-10 and 13-16 of the oestrous cycle. Total RNA was purified from non-incubated cells and from cells incubated for 48 h in the absence or presence of luteinising hormone (LH). The semi-quantitative RT-PCR technique, involving coamplification of the target and control cDNA (beta-actin or 18S rRNA), was used to examine gene expression. It was found that the genes coding for opioid precursors are expressed in both non-incubated and incubated porcine luteal cells representing the early, mid- and late luteal phase. In non-incubated cells, only POMC mRNA content changed during CL development, whereas the expression of PENK and PDYN genes remained relatively constant. Additionally, the treatment of cells with LH markedly affected the expression of POMC and PENK, but no influence on PDYN expression was observed. The present study indicates that porcine luteal cells may produce opioid peptides and that gene expression of their precursors (except for PDYN) may be modulated in these cells by LH. Moreover, the present results support the involvement of opioid peptides in local regulation within the CL of the pig.

Driving force of stacking-fault formation in SiC p-i-n diodes.

The driving force of stacking-fault expansion in SiC p-i-n diodes was investigated using optical emission microscopy and transmission electron microscopy. The stacking-fault expansion and properties of the partial dislocations were inconsistent with any stress as the driving force. A thermodynamic free energy difference between the perfect and a faulted structure is suggested as a plausible driving force in the tested diodes, indicating that hexagonal polytypes of silicon carbide are metastable at room temperature.

Influence of hyperpnea on airway surface fluid volume and osmolarity in normal humans.

To determine the effect of hyperpnea on the characteristics of periciliary liquid, we collected airway surface fluid (ASF) and measured its osmolarity in 11 normal people while they breathed dry, frigid air (-17 +/- 1.2 degrees C) at minute ventilations (VE) of 10, 40, and 80 l/min through a heat exchanger. The ASF was collected at the fifth tracheal ring by absorption onto filter paper pledgets inserted via fiber-optic bronchoscopy. Hyperpnea had no influence on the amount of ASF recovered (ASF volume at a VE of 10 l/min = 12.0 +/- 2.0 microl; at 80 l/min = 8.8 +/- 1.5 microl; P = 0.28) or its osmolarity (at a VE of 10, 40, and 80 l/min = 326 +/- 15, 323 +/- 11, and 337 +/- 12 mosM, respectively; P = 0.65). These findings demonstrate that the tracheal mucosa of normal subjects does not dessicate during hyperpnea and that hypertonicity of the periciliary fluid does not develop even at high levels of ventilation.

Inhibition of nitric oxide synthesis attenuates thermally induced asthma.

To determine whether the inhibition of nitric oxide (NO) synthesis attenuates thermally induced obstruction, we had 10 asthmatic volunteers perform isocapnic hyperventilation with frigid air after inhaling 1 mg of N(G)-monomethyl-L-arginine (L-NMMA) or isotonic saline in a blinded fashion. The challenges were identical in all respects, and there were no differences in baseline lung function [1-s forced expiratory volume (FEV(1)); saline 2.8 +/- 0.3 liters, L-NMMA 2.9 +/- 0.3 liters; P = 0.41] or prechallenge fractional concentration of nitric oxide in the exhaled air (FENO) [saline 23 +/- 6 parts/billion (ppb), L-NMMA 18 +/- 4 ppb; P = 0.51]. Neither treatment had any impact on the FEV(1), pulse, or blood pressure. After L-NMMA, FENO fell significantly (P < 0.0001), the stimulus-response curves shifted to the right, and the minute ventilation required to reduce the FEV(1) 20% rose 53.5% over control (P = 0.02). The results of this study demonstrate that NO generated from the airways of asthmatic individuals may play an important role in the pathogenesis of thermally induced asthma.

Exhaled nitric oxide and thermally induced asthma.

The purpose of the present study was to determine if nitric oxide (NO) is involved in the pathogenesis of thermally induced asthma. To provide data on this issue, 10 normal and 13 asthmatic subjects performed isocapnic hyperventilation with frigid air while the fractional concentration of NO in the expirate air (FENO) was serially monitored with a chemiluminescence analyzer. FEV1 was measured before and after hyperpnea. Prior to and throughout the challenge, the asthmatics had significantly larger values for FENO (baseline FENO normal, 11 +/- 2 ppb; asthma, 16 +/- 1; p = 0.03). Posthyperpnea, the normal subjects had little change in bronchial caliber (deltaFEV1 baseline to 5 min posthyperpnea, -3.5 +/- 1.5%; p = 0.06), whereas the patients with asthma developed significant airway obstruction (deltaFEV1, -27.7 +/- 2.9%; p = 0.0001). During hyperventilation, the volume of NO rose in both groups. The asthmatic subjects, however, generated approximately 55% more NO/min than did the normal control subjects even though their level of ventilation was approximately 66% less. In contrast to the normal subjects, NO production in the asthmatics continued into the recovery period after the challenge stopped and FENO rose temporally as the airflow limitation developed. These results suggest that NO plays an intimate role in the development of airway obstruction that follows hyperpnea.

Implementation of a blood irradiation program at a community cancer center.

BACKGROUND: Blood component irradiation is an accepted method of preventing transfusion-associated GVHD. Previous publications have largely focused on the technical aspects of the irradiation process itself, but relatively little attention has been paid to the details associated with the implementation of a blood irradiation program at the level of a community cancer center. STUDY DESIGN AND METHODS: An observational study was performed, detailing the specific operational, documentation, and quality assurance measures employed in providing a blood component-irradiation service within the institutional context of a community cancer center. RESULTS: The Montgomery Cancer Center irradiated 589 units of blood components in 1998 and 1999 to provide a local blood bank with an alternative for procurement of irradiated blood components while complying with applicable quality assurance and regulatory requirements. CONCLUSION: Blood component irradiation is within the scope of most well-equipped and adequately staffed community cancer centers. Establishment of a blood component irradiation program requires scrupulous physics and dosimetry support, both to ensure the quality of the irradiated component and to satisfy governmental agency regulatory requirements.

Comparative effects of long-acting beta2-agonists, leukotriene receptor antagonists, and a 5-lipoxygenase inhibitor on exercise-induced asthma.

BACKGROUND: Exercise-induced asthma (EIA) is a common problem that can be controlled with long-acting beta-agonists and leukotriene-modifying compounds. There is, however, limited information on the comparative effectiveness of the two classes of drugs, as well as the relative potencies of the antileukotriene agents. OBJECTIVE: The purpose of the present study was to provide data on the above issues. METHODS: We performed a random-order, blinded, double-dummy, placebo-controlled trial in 10 patients with EIA. Each subject received standard single doses of salmeterol, montelukast, zafirlukast, zileuton, and placebo on separate days. The participants performed 4 minutes of cycle ergometry while breathing frigid air 1, 4, 8, and 12 hours after administration of the test agents. The primary endpoint was the extent of the decrement in the FEV(1) 10 minutes after exertion. RESULTS: With placebo, symptomatic airway narrowing developed at all times (mean +/- SE decrease in FEV(1) ranged between 21% +/- 5% and 26% +/- 5%). Salmeterol acted quickly and significantly blunted the obstructive response for 12 hours (DeltaFEV(1) first hour: 8% +/- 3%; DeltaFEV(1) twelfth hour: 8% +/- 3%; P <.0001 vs placebo and P =.72 vs time). The leukotriene-modifying agents produced effects within 1 hour of ingestion. Like salmeterol, montelukast and zafirlukast also offered long-lasting protection, and there were no significant differences between them (montelukast DeltaFEV(1) twelfth hour: 9% +/- 4%; zafirlukast DeltaFEV(1) twelfth hour: 11% +/- 2%; P =.75) or the beta(2)-agonist (montelukast vs salmeterol: P =.72; zafirlukast vs salmeterol: P =.48). Zileuton provided equivalent prophylaxis for the first 4 hours (DeltaFEV(1) fourth hour: 11% +/- 2%); however, by 8 hours, it was less efficacious than all of the other active compounds, and by 12 hours it did not differ from placebo (DeltaFEV(1) twelfth hour: 19% +/- 4%; P =.33). CONCLUSIONS: Single doses of the currently available leukotriene receptor antagonists provide prompt effective and persistent defense against EIA that equals that seen with a long-acting beta(2)-agonist. The synthesis inhibitor zileuton affords a comparable magnitude of prophylaxis but has a considerably shorter duration of action.

Persistent increase in the amount of aquaporin-5 in the apical plasma membrane of rat parotid acinar cells induced by a muscarinic agonist SNI-2011.

SNI-2011 induces the long-lasting increase in the amount of aquaporin-5 (AQP5) in apical plasma membranes (APMs) of rat parotid acini in a concentration-dependent manner. This induction was inhibited by p-F-HHSiD, U73122, TMB-8, or dantrolene but not by bisindolmaleimide or H-7, indicating that SNI-2011 acting at M(3) muscarinic receptors induced translocation of AQP5 via [Ca(2+)](i) elevation but not via the activation of protein kinase C. In contrast, acetylcholine induced a transient translocation of AQP5 to APMs. SNI-2011 induces long-lasting oscillations of [Ca(2+)](i) in the presence of extracellular Ca(2+). Thus, SNI-2011 induces a long-lasting translocation of AQP5 to APMs coupled with persistent [Ca(2+)](i) oscillations.

Enhancement by epinephrine of benzylpenicillin transport in rat small intestine.

The perfusion of rat small intestinal lumen with epinephrine (0.1 mM) resulted in a significant increase in the amount of benzylpenicillin (BP) transported from the mucosal to the serosal side. In this study, the perfusion of the lumen with phenylephrine, clonidine, dobutamine, or salbutamol had no effect on BP transport. However, the combinations of phenylephrine and isoproterenol, clonidine and isoproterenol, and phenylephrine and salbutamol increased the BP transport to a similar extent as that observed with epinephrine alone. Tolazolin or propranolol inhibited the epinephrine-induced increase in BP transport. An increase in the intracellular concentration of cAMP in conjunction with specific activation of either alpha(1)- or alpha(2)-adrenoceptors induced an increase in BP transport similar to that observed in response to epinephrine alone. Staurosporine or N-[2-(methylamino)ethyl]-5-isoquinolinesulfonamide abolished the epinephrine-induced increase in BP transport. Peptides or either zwitterionic or anionic cephalosporins also blocked the effect of epinephrine on BP transport. The extent of BP uptake into brush border or basolateral membrane vesicles prepared from epinephrine-perfused intestinal loops was markedly greater than that into vesicles prepared from control loops. The perfusion of intestinal lumen with carbonyl cyanide p-trifluoromethoxy phenylhydrazone, amiloride, or ouabain inhibited epinephrine-induced BP transport. These results indicate that the interaction of epinephrine with both beta(2)-adrenoceptors and either alpha(1)- or alpha(2-)adrenoceptors markedly stimulates the BP transport, an effect likely mediated by the enhancement of the function in the brush border membrane of intestinal epithelial cells coupled with the generation of an H(+) gradient.

Integrated response of the upper and lower respiratory tract of asthmatic subjects to frigid air.

To evaluate the influence of cold air hyperpnea on integrated upper and lower airway behavior, 22 asthmatic volunteers hyperventilated through their mouths (OHV) and noses (NHV) while pulmonary and nasal function were determined individually and in combination. In the isolated studies, OHV at a minute ventilation of 65 +/- 3 l/min lowered the 1-s forced expiratory volume (FEV(1)) 24 +/- 2% (P < 0. 001) and NHV (40 l/min) induced a 31 +/- 9% (P < 0.001) increase in nasal resistance (NR). In the combined studies, oral hyperpnea reduced the FEV(1) (DeltaFEV(1) 26 +/- 2%, P < 0.001) and evoked a significant rise in NR (DeltaNR 26 +/- 9%, P = 0.01). In contrast, NHV only affected the upper airway. NR rose 33 +/- 9% (P = 0.01), but airway caliber did not change (DeltaFEV(1) 2%, P = 0.27). The results of this investigation demonstrate that increasing the transfer of heat and water in the lower respiratory tract alters bronchial and nasal function in a linked fashion. Forcing the nose to augment its heat-exchanging activity, however, reduces nasal caliber but has no effect on the intrathoracic airways.

Uncontrolled oxygen administration and respiratory failure in acute asthma.

STUDY OBJECTIVES: To determine if 100% oxygen administration adversely influences gas exchange in acutely ill asthmatic subjects. DESIGN: Prospective preinterventional and postinterventional comparison. SETTING: University hospital emergency department. PATIENTS: Thirty-seven asthmatic subjects seeking care for symptomatic exacerbations. INTERVENTIONS: Twenty minutes of 100% oxygen administration by face mask. MEASUREMENTS AND RESULTS: Arterial blood gases and FEV(1) were measured before and during the last minute of oxygen administration. On presentation, the subjects had moderately severe airway obstruction (FEV(1), 49.1 +/- 3.6% of predicted); hypocarbia (PaCO(2), 36.8 +/- 1.1 mm Hg); hypoxemia (PaO(2), 70.2 +/- 2.5 mm Hg); and respiratory alkalosis (pH, 7.43 +/- 0.01). During oxygen breathing, 25 patients (67.6%) experienced elevations in PaCO(2) ranging from 1 to 10 mm Hg (mean, 4.1 +/- 0.6 mm Hg; p = 0.0003). The increase was considered to be a physiologic manifestation of the Haldane effect (ie, < or = 2 mm Hg) in 10 subjects, but in the remaining 15 subjects (40.5% of the total studied), the elevation represented worsening gas exchange. In seven of these patients (46.7%), hypercapnic respiratory failure developed (PaCO(2) before oxygen, 39.6 +/- 0.6; during oxygen, 44.7 +/- 0.7 mm Hg; p = 0.005), and in six patients (40%), it worsened (PaCO(2) before oxygen, 46.8 +/- 1.9; during oxygen, 52.0 +/- 3.1 mm Hg; p = 0.03). In general, the tendency toward hypercarbia was the greatest in the participants with the most severe airway obstructions. CONCLUSIONS: Our data demonstrate that the administration of 100% oxygen to acutely ill asthmatics may adversely influence carbon dioxide elimination.

alpha(1)-adrenoceptor-induced trafficking of aquaporin-5 to the apical plasma membrane of rat parotid cells.

Incubation of rat parotid tissue with 10 microM epinephrine resulted in a transient and marked trafficking of aquaporin-5 (AQP5) from intracellular membranes to the apical plasma membrane (APM) that was maximal at 1 min. This effect of epinephrine was mimicked by phenylephrine, but not by clonidine, dobutamine, or salbutamol, and it was inhibited by phentolamine, but not by propranolol. Furthermore, the epinephrine-induced trafficking of AQP5 was inhibited by phospholipase C inhibitor U73122 as well as dantrolene and TMB-8, both of which inhibit the release of Ca(2+) from intracellular stores. Cytochalasin D and tubulozole-C also inhibited this action of epinephrine. These results indicate that epinephrine, acting at alpha(1)-adrenoceptors, induces the trafficking of AQP5 to the APM by triggering the release of Ca(2+) from intracellular stores through inositol 1,4,5-trisphosphate and ryanodine receptors. In addition, the potent involvement of the cytoskeleton was shown in the epinephrine-induced trafficking of AQP5.

Salmeterol does not compromise the bronchodilator response to albuterol during acute episodes of asthma.

PURPOSE: The present study was undertaken to determine whether regular use of salmeterol reduces the emergency effectiveness of albuterol. PATIENTS AND METHODS: Acutely ill asthmatic patients chronically taking salmeterol, and similar patients who were not taking salmeterol, were treated with albuterol, either as three aerosols of 2.5 mg every 20 minutes for 1 hour or two doses of 5.0 mg every 20 minutes. Peak expiratory flow measurements were monitored before and after each treatment. The time to disposition and the number of return visits were also recorded. RESULTS: One hundred fourteen patients, 57 who took salmeterol and 57 who served as control patients, completed the study. Thirty-three patients in each group received the lower dose of albuterol, and 24 were given the larger amount. There were no significant pretreatment differences between the salmeterol and control groups in the severity of symptoms or the degree of airway obstruction. Both albuterol regimens improved peak flow. Responses in the control group and in the salmeterol group were similar (low-dose albuterol increase in peak flow = 49%, control = 35%, P = 0.37; high-dose albuterol increment in peak flow = 43%, control = 41%, P = 0.81). There were no significant differences between the control group and the salmeterol group in the mean length of stay, the proportion of subjects admitted to the hospital, or the number of return visits. CONCLUSIONS: In patients with asthma, chronic use of salmeterol doses not interfere with the effects of standard doses of albuterol for the treatment of acute decompensations.