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In large-to-massive rotator cuff tears (MRCTs), incorporating the long head of the biceps tendon (LHBT) with arthroscopic partial rotator cuff and margin convergence can improve clinical outcomes and preserve the acromio-humeral interval (AHI) during mid-term follow-up. The purpose of this study was to evaluate mid-term clinical and radiological outcomes of arthroscopic biceps-incorporating rotator cuff repair with partial release of the LHBT and footprint medialization through the Neviaser portal in MRCTs.This study enrolled 107 patients (38 males and 69 females, mean age: 64.9 ± 8.6 years) with MRCTs. A novel arthroscopic biceps-incorporating repair was performed by footprint medialization, with a partially released biceps tendon covering central defects. Clinical outcomes such as pain VAS, KSS, ASES, UCLA, SST and CS scores and ROM were evaluated at a mean follow-up time of 35 months (range 12-132 months). Serial radiographs with a mean postoperative MRI follow-up duration of 33 months were used to evaluate AHI, tendon integrity, fatty infiltration (FI) and muscle hypotrophy.Postoperative pain VAS, KSS, ASES, UCLA, SST, and CS scores and ROM (except external rotation) were improved significantly. AHI also improved significantly from 8.6 to 9.3 mm. According to Sugaya's classification, type I, II, III, IV, or V healing status was found in 30 (28.0%), 29 (27.1%), 26 (24.3%), 14 (13.1%), and 8 (7.5%) patients, respectively. The retear rate was 22 (20.6%).Novel biceps-incorporating cuff repair with footprint medialization yielded satisfactory outcomes in MRCT patients at the 3-year follow-up. A partially released, repaired biceps tendon provided superior stability with preserved AHI similar to that of anterior cable reconstruction.IV.

The purpose of this study was to analyze the epidemiology of T-score discordance between the spine and femur in the South Korean population and compare the prevalence of T-score discordance between the Korean osteoporosis population and atypical femoral fracture (AFF) patients.A total of 12,422 subjects from the Korea National Health and Nutrition Examination Survey were reviewed retrospectively. T-score discordance was defined as a difference of ≥ 1 standard deviation between the lumbar spine (LS) and femoral neck (FN) bone mineral density (BMD). The prevalence of T-score discordance (low LS [LS BMDFN BMD], low FN [LS BMDFN BMD], and total [low LS + low FN]) was investigated in the osteoporosis and non-osteoporosis groups and stratified by sex and age. T-score discordance of 63 patients with AFFs diagnosed at a single institution was compared with that of the Korean osteoporosis population using propensity score matching.T-score discordance was prevalent in the Korean osteoporosis population (44.8%), and low LS discordance (37.5%) was more frequently seen than low FN discordance (7.2%) (T-score discordance was highly prevalent in the Korean osteoporosis population, and low LS discordance was more common than low FN discordance. Nevertheless, the prevalence of low LS discordance was significantly higher in AFF patients than in the Korean osteoporosis population.

Background We determined whether postoperative intravenous (IV) iron supplementation could reduce transfusion rate in patients undergoing staged bilateral total knee arthroplasty (TKA). Furthermore, we examined whether hemoglobin (Hb) levels and iron profile differed between patients with and without postoperative IV iron supplementation. Methods This retrospective, comparative cohort study included 126 patients who underwent primary staged bilateral TKA during a single hospitalization. The second TKA was performed at a week’s interval. Group iron (n = 65) received IV iron immediately after each surgery, while patients in group no-iron (n = 61) received no iron after surgery. Transfusion rate, change in Hb levels, and iron profile including serum iron, ferritin, total iron binding capacity, and transferrin saturation were evaluated preoperatively; on postoperative days 1, 2, and 4 after the first TKA; and postoperative days 1, 2, 4, and 7, 6 weeks, and 3 months after the second TKA. Results There were no significant differences in Hb levels and transfusion rate following staged bilateral TKA between patients with and without postoperative IV iron supplementation although serum iron profiles were improved in patients with IV iron supplementation. Conclusion Postoperative IV iron supplementation immediately after acute blood loss caused by TKA was not effective in improving the transfusion rate. Therefore, surgeons should use protocols other than postoperative IV iron supplementation for reducing the transfusion rate in patients undergoing staged bilateral TKA in a single hospitalization. Level of Evidence III.

Background This study aimed to determine the prevalence of excessive lateral pressure syndrome (ELPS) in potential candidates for high tibial osteotomy (HTO) using single-photon emission computed tomography–computed tomography (SPECT–CT). We also sought to identify risk factors related to the presence of ELPS. Methods This retrospective study included 150 patients (216 knees) who were candidates for HTO from an initial screening of 3579 patients (7158 knees). There were 183 female and 33 male knees with a mean age of 58 years. The presence of ELPS was defined as a grade 3 uptake on the SPECT–CT at the lateral PF joint. To determine the risk factors related to the ELPS, multivariate regression analysis was performed with independent demographic and radiographic variables. Results Increased uptake on the lateral side of the PF joints was detected in 120 knees (56% of total subjects). Of these, 34 (16%) knees presented with a grade 3 uptake, which indicated the presence of ELPS. No single risk factor had significant associations with the presence of ELPS. Conclusions A considerable number of the knees that were candidates for HTO had ELPS. Nonetheless, we did not find any risk factor related to the presence of ELPS. These results suggest that surgeons should be cautious when diagnosing concomitant ELPS despite acceptable radiographic findings from patellofemoral joints when performing HTO.

BACKGROUND Some patients with recurrent symptomatic instability after primary anterior cruciate ligament (ACL) reconstruction have an extension deficiency (ED). This study (a) compared preoperative clinical conditions between the ED and non-ED groups undergoing revision ACL reconstruction, (b) documented clinical and arthroscopic findings in ACL-reconstructed patients with reinstability and ED, and (c) determined whether the ED could be resolved and whether the clinical results of revision surgery differed between the ED and non-ED groups. METHODS This study included 58 patients who underwent revision ACL reconstruction. Patients were divided into the ED and non-ED groups. Preoperatively, the demographics and clinical conditions of the two groups were compared. Intraoperatively, the pathological structures that related to ED were documented. After surgery, the degree of postoperative ED and functional outcomes were compared between the two groups at 2-year follow-up. RESULTS The International Knee Documentation Committee subjective score and SF-36 physical component summary scores were worse in the ED group than the non-ED group preoperatively (54 vs 48 [P = 0.014]; 42 vs 39 [P = 0.031], respectively). Intraoperatively, the ED group showed significantly more frequent graft malposition (50% vs 5%), anvil osteophytes (44% vs 0%), and scarring around posterior intercondylar notch (100% vs 0%). However, there was no difference in the degree of postoperative ED and functional outcome between the two groups at follow-up. CONCLUSIONS ED in patients with recurrent instability after primary ACL reconstruction could be treated with good clinical result by addressing the pathological conditions causing ED in addition to ACL re-reconstruction.

The time resolution and prediction accuracy of the power generated by building-integrated photovoltaics are important for managing electricity demand and formulating a strategy to trade power with the grid. This study presents a novel approach to improve short-term hourly photovoltaic power output predictions using feature engineering and machine learning. Feature selection measured the importance score of input features by using a model-based variable importance. It verified that the normative sky index in the weather forecasted data had the least importance as a predictor for hourly prediction of photovoltaic power output. Six different machine-learning algorithms were assessed to select an appropriate model for the hourly power output prediction with onsite weather forecast data. The recurrent neural network outperformed five other models, including artificial neural networks, support vector machines, classification and regression trees, chi-square automatic interaction detection, and random forests, in terms of its ability to predict photovoltaic power output at an hourly and daily resolution for 64 tested days. Feature engineering was then used to apply dropout observation to the normative sky index from the training and prediction process, which improved the hourly prediction performance. In particular, the prediction accuracy for overcast days improved by 20% compared to the original weather dataset used without dropout observation. The results show that feature engineering effectively improves the short-term predictions of photovoltaic power output in buildings with a simple weather forecasting service.

Rationale: Peroneal nerve injury is one of the major complications that may occur after closing wedge high tibial osteotomy (CWHTO). In contrast, the reduced risk of the peroneal nerve injury has been considered as one of the advantages of opening wedge HTO (OWHTO). Patient concerns: A 61-year-old male who underwent OWHTO showed a dropped big toe immediately after surgery. Diagnosis: Injury of deep peroneal nerve was confirmed by electrodiagnostic study. It was probably caused by a posterolaterally protruded screw. Interventions: The protruded screw was replaced with a shorter one 3 weeks after OWHTO. Outcomes: The motor weakness and sensory reduction were completely recovered at 9 months after surgery. Lessons: OWHTO has been known to be safe from peroneal nerve injury. However, considering the anatomical course of deep peroneal nerve, great care should be taken to avoid damage to the deep peroneal nerve while drilling holes and inserting distal screws toward the posterolateral aspect of the proximal tibia.

Electrochromic glazing can dynamically control solar heat gains of windows depending on the indoor and outdoor environments. This means that the energy performance of buildings with the electrochromic glazing window systems are affected by control parameters and climatic conditions. This study proposes an optimized electrochromic glazing control parameter and value to improve the energy performance and sustainability of medium-sized commercial building in different climates. It characterized the annual heating and cooling energy consumption of a typical building model with the window systems for different potential control parameters, such as outdoor air temperature, room air temperature, solar radiation incident on the window, and global horizontal solar irradiance. A pattern search algorithm was applied to derive the optimal control value of each parameter for four window orientations in six different climatic conditions. Our results show that for the electrochromic glazing window operation, outdoor air temperature is the most effective control parameter for reducing both cooling and heating energies in all window orientations and climatic conditions. When the electrochromic glazing window on three sides of building is controlled at the optimal outdoor air temperature, the cooling coil size of the air handling unit decreased by 16.5% on average under different climatic conditions. Furthermore, the daily peak cooling loads reduced by an average of 11.8%. The annual heating and cooling energy consumption decreased by 46.1 kWh (17.4%) on average per unit window area compared with the typical static window case under six different locations.

Background Occasionally, patients experience new or increased ankle pain following total knee arthroplasty (TKA). The aims of this study were to determine (1) how the correction of varus malalignment of the lower limb following TKA affected changes in alignment of the ankle and hindfoot, (2) the difference in changes in alignment of the ankle and hindfoot between patients with and without ankle osteoarthritis (OA), and (3) whether the rate of ankle pain and the clinical outcome following TKA differed between the 2 groups. Methods We retrospectively reviewed prospectively collected data of 56 patients (99 knees) treated with TKA. Among these cases, concomitant ankle OA was found in 24 ankles. Radiographic parameters of lower-limb, ankle, and hindfoot alignment were measured preoperatively and 2 years postoperatively. In addition, ankle pain and clinical outcome 2 years after TKA were compared between patients with and without ankle OA. Results The orientation of the ankle joint line relative to the ground improved from 9.4° of varus to 3.4° of varus, and the valgus compensation of the hindfoot for the varus tilt of the ankle joint showed a 2.2° decrease following TKA. Patients in the group with ankle OA showed decreased flexibility of the hindfoot resulting in less preoperative valgus compensation (p = 0.022) compared with the group without ankle OA. The postoperative hindfoot alignment was similar between the 2 groups because of the smaller amount of change in patients with ankle OA. The group with ankle OA had a higher rate of increased ankle pain (38% compared with 16%) as well as a worse Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score (mean of 22.2 compared with 14.2) following TKA. Conclusions A considerable proportion of patients who underwent TKA had concomitant ankle OA with reduced flexibility of the hindfoot. These patients experienced increased ankle pain following TKA and a worse clinical outcome. Level of evidence Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

The purpose of this study was to assess the overall clinical results and range of motion (ROM) after total knee arthroplasty (TKA) in patients with preoperative stiffness. We also aimed to determine whether the severity or cause of the stiffness can affect the clinical outcome after surgery. This retrospective study included 122 knees (117 patients) with follow-up of more than 2 years (mean age, 64.3 years). TKA was performed using posterior-stabilized, varus-valgus constrained (VVC), and hinged prostheses. To determine the effect of the severity of stiffness on the clinical outcome, the subjects were divided into two groups: the severe group (preoperative ROM ≤ 50°; 18 knees) and the moderate group (preoperative ROM, 50°-90°; 104 knees). Then, clinical results and ROM were compared according to the severity or cause of preoperative stiffness. After surgery, preoperative ROM (mean, 78°; range, 25°- 90°) was improved (mean, 107°; range, 70°- 130°). The severe group more frequently used the VVC or hinged prostheses (72% vs. 18%). Furthermore, the severe group had worse knee and function scores as well as more complications (33% vs. 13%), even though the severe group had a greater ROM increment (47° vs. 27°) after surgery. Patients with osteoarthritis and rheumatoid arthritis showed better ROM and clinical results compared to patients with infectious or traumatic arthritis. Although TKA in stiff knees can be successful, the results are inferior in knees with severe stiffness and knees with infectious or traumatic arthritis.

There is no comparative study regarding surgical outcomes between microsurgical extraforaminal decompression (MeFD) and posterior lumbar interbody fusion (PLIF) for the treatment of lumbar foraminal stenosis (LFS). Therefore, the purpose of this study was to compare the surgical outcomes of LFS using two different techniques: MeFD alone or PLIF. For the purposes of this study, a prospectively collected observational cohort study was conducted. Fifty-five patients diagnosed with LFS who were scheduled to undergo spinal surgery were included in this study. According to the chosen surgical technique, patients were assigned to either the MeFD group (n = 25) or the PLIF group (n = 30). The primary outcome was Oswestry Disability Index (ODI) score at 1 year after surgery. The baseline patient characteristics and preoperative ODI score, visual analog scale (VAS) scores for back and leg pain, and Short Form-36 score were not significantly different between the two groups. At 12 months postoperative, the mean ODI score in the MeFD and PLIF groups was 25.68 ± 14.49 and 27.20 ± 12.56, respectively, and the 95 % confidence interval (−9.76–6.73) was within the predetermined margin of equivalence. The overall ODI score and VAS scores for back and leg pain did not differ significantly over the follow-up assessment time between the two groups. However, the ODI score and VAS scores for back and leg pain improved significantly over time after surgery in both groups. In the MeFD group, revision surgery was required in three patients (12 %). This study demonstrated that MeFD alone and PLIF have equivalent outcomes regarding improvement in disability at 1 year after surgery. However, the higher rate of revision surgery in the MeFD group should emphasize the technically optimal amount of decompression.

Background: Less mature athletes exhibit biomechanical parameters during cutting maneuvers that may place these athletes at greater risk for injury than their more mature counterparts, especially if the maneuvers are unanticipated. However, most studies on risk factors for anterior cruciate ligament (ACL) injury have focused on neuromuscular and knee kinematic differences between the sexes, not on the biomechanical parameters between specific sporting maneuvers. Hypotheses: (1) Anticipation will have a greater effect than the type of cutting maneuver (side- vs cross-cutting) in terms of the biomechanical risk factors for ACL injuries, and (2) the biomechanical risk factors will be different between the 2 types of maneuvers. Study Design: Controlled laboratory study. Methods: Thirty-seven young, male middle school soccer players participated in this study. Three-dimensional motion analysis featuring ground-reaction force and electromyography of the right leg was used. Kinematics, kinetics, and electromyography data for each athlete were analyzed during anticipated and unanticipated side- and cross-cutting maneuvers. The differences between anticipated and unanticipated states as well as between side- and cross-cutting maneuvers were calculated and compared. Results: After unanticipated side-cutting, the time to peak ground-reaction force was longer and peak values were smaller compared with anticipated side-cutting. Flexion, valgus, and internal rotations in the knee joint were larger, and greater flexion and valgus moments were observed. The vastus lateralis and vastus medialis showed lower activity, and the lateral gastrocnemius showed higher activity after unanticipated side-cutting maneuvers. With unanticipated cross-cutting, the time to peak ground-reaction force was longer and peak values were smaller compared with anticipated cross-cutting, and the lateral gastrocnemius showed higher activity. Differences in the peak values of the mediolateral and vertical forces were smaller in the cross-cutting maneuver than in side-cutting. Changes in flexion and adduction of the hip joint, flexion of the knee joint, and inversion of the ankle joint were larger during side-cutting. Conclusion: Although there were some interactions between direction and anticipation, anticipating a cutting maneuver generally had a greater effect than the type of maneuver when there was no significant interaction. Clinical Relevance: Increases in the valgus angle and moment of the knee joint and higher lateral gastrocnemius activity during the late period showed an association with ACL injury risk factors during side-cutting, and higher lateral gastrocnemius activity during the early period showed an association with injury risk factors during cross-cutting.

Nowadays a large portion of energy consumption is depends on Residential Building. For these reasons Mechanical ventilation, colling, heating such things also be improved. But Occupants take action to control their indoor environments to adjust their individual flavour. Window Opening & closing If this result is universally applicable most preferred behaviour to adjust their indoor environment. However these behaviour causes an increase in energy consumption in the building. Therefore, if the window opening and closing behavior can be predicted, it will lead to an increase the comfort in the building and a decrease in the energy consumption. Previous studies have confirmed that window opening and closing behavior is significantly affected by ambient temperature. This also indicates that the season also affects window opening. It can be seen that the machine learning algorithm has better prediction than the traditional regression model. The purpose of this study is to investigate the effects of building information (location, number of floors, area, completion year) and human characteristic for indoor environmental control(heating setting temperature), not on the environmental parameters(temperature, humidity, fine dust, etc.) applied to previous machine learning models in the prediction of window opening and closing behavior. If this result is normally applicable, it will make more realistic predictions possible than when predicting with existing environmental parameters alone. This will give a plausibility to the results of simulations on actual buildings.

Five different chopped frozen garlic products samples, three from Chinese and two from Korean origins being commercially available products in Korean market, were used to confirm their pre-pasteurization or pre-irradiation status by screening (direct epifluorescent filter technique/aerobic plate counts, DEFT/APC; electronic nose, E-nose; photostimulated luminescence, PSL) and identification (thermoluminescence, TL; electron spin resonance, ESR) techniques. Some parts of samples were gamma-irradiated at 1 kGy to be used as control samples in irradiation history identification. DEFT/APC and e-nose successfully showed distinct results between the domestic and imported samples. The PSL photon counts of all the unknown samples were less than 700 (negative), while most of 1 kGy-irradiated samples gave PSL photon counts more than 5,000 (positive). The domestic unknown samples produced the TL glow peaks after 300°C or more, whereas the imported samples showed TL peaks at the range of 240～250°C. A clear TL glow peak was obtained from all irradiated samples at 150～250°C. The unknown samples of Chinese origin gave radiation-specific cellulose ESR signal that was not shown by domestic samples. A multiple step of applying the physical analytical methods is recommended for the effective identification of irradiation status on chopped frozen garlic products.

The aim of this study is to evaluate the applicability of adsorption models for understanding adsorption properties of adsorbents. For this study, the adsorption charateristics of NO3 by commercial anion exchange resin, PA-308, were investigated in bach process. The adsorption kinetic data for NO3 by anion exchange resin showed two stage process comprising a fast initial adsorption process and a slower second adsorption process. Both the pseudo-first-order kinetic model and the pseudo-second-order kinetic model could not be used to predict the adsorption kinetics of NO3 onto anion exchange resin for the entire sorption period. Only the fast initial portion (t≤ 20 min) of adsorption kinetics was found to follow pseudo-first-order kinetic model and controlled mainly by external diffusion that is very fast and high, whereas, the slower second portion (t > 20 min) of adsorption kinetics seems to be controlled by a second-order chemical reaction and by intraparticle diffusion.

The purpose of this study was to clarify the effects of the environmental education system focusing on the knowledge, attitude and practice in relation to environmental education to the students in Mokpo middle school. The study is accomplished by the survey which includes a total of 268 inquiry lists sampled from four groups of the middle school, one of which composing of two middle schools having the environmental curriculum, hereafter referred as 'the case group' and the other group of two middle schools without the curriculum, hereafter referred as the 'the control group'. From the results of the average scores on the environmental knowledge, attitude and practice between the two groups, the case group showed better knowledge scores than the control group (p), economic status, academic achievement and the necessity of environment conservations in order. The factor most affecting to environmental attitude and practice were the interest in environmental problems of the parents.

To observe changes in fatty infiltration (FI) of the teres minor without tear of the teres minor in a postoperative magnetic resonance imaging and to evaluate the influence of FI of the teres minor in the clinical outcomes of rotator cuff repair.Of 816 patients who underwent rotator cuff repair, 51 (6.3%) had FI of the teres minor without tear involvement and 30 cases were available for postoperative magnetic resonance imaging. FI and functional outcome scores were assessed and compared with the control group that had no FI of the teres minor selected by a propensity score matching.FI of the teres minor was observed in various degrees (grade 1 in 9, grade 2 in 9, grade 3 in 6, and grade 4 in 6). The degree of FI was not related to the amount of tendon involvement of a rotator cuff tear (P = .240). All postoperative functional outcome scores (12.6 ± 1.2 months; range, 11-17), including pain visual analog scale, Simple Shoulder Test, and American Shoulder and Elbow Surgeons Score, significantly improved (all P.001), and there were no significant differences compared with that of the control group. In most of the cases, FI of the teres minor was unchanged (P = .317).FI of the teres minor without tear involvement can be observed in a rotator cuff tear as a possibly incidental finding of unknown clinical significance. Its cause has not been determined, and it appears that FI of the teres minor does not appear to improve, at least at the 1-year follow-up. Nevertheless, the functional outcomes of the repair were successful in our study; therefore, rotator cuff repair can be performed without a great deal of concern in the presence of FI in the teres minor.Level III, retrospective comparative study.

The aim of this study was to examine the relationship of wheezing to airflow obstruction during acute episodes of asthma in patients who had CVA (cough variant asthma). Two groups of asthmatic children, one group with a past history of CVA (n = 13) and the other group without such a history (n = 14), were followed longitudinally for 12 months. During that time, they were evaluated for the presence of wheezing and the severity of airflow obstruction during acute episodes of asthma. Significant airflow obstruction occurred free of wheezing more frequently, and the presence of clinical wheezing was associated with more severe airflow limitation, in asthmatic patients with a past history of CVA than in those without such a history. We conclude that asthmatic patients who have experienced CVA develop the wheezing symptom at a higher level of airflow obstruction.

Study objective: There is growing evidence that regular b2-agonist use in patients with asthma is associated with decreased airway caliber and increased bronchial responsiveness. The aim of this study was to determine whether regular treatment with b2-agonists induces changes in lung function and bronchial responsiveness in patients with primary ciliary dyskinesia. Design: A randomized, double-blind, placebo-controlled, crossover study. Patients: Nineteen children with primary ciliary dyskinesia. Interventions: Subjects received inhaled salbutamol or identical placebo (2 3 100 mg qid) for periods of 6 weeks with a wash-out period of 4 weeks. Measurements and results: FEV1 was measured before and 3 weeks and 6 weeks after salbutamol or placebo treatment. High-dose methacholine inhalation tests were performed before and 6 weeks after each treatment. The provocative concentration of methacholine producing a 20% fall in FEV1 (PC20) and maximal airway narrowing (MDFFEV1) was measured. No significant change in FEV1 was observed during the salbutamol or placebo periods. No significant differences in the parameters of bronchial responsiveness (PC20 and MDFFEV1) were noted as the result of either salbutamol or placebo treatment. Conclusion: Our data have shown that salbutamol, inhaled regularly for 6 weeks, did not cause either a decline in lung function or an increase in bronchial responsiveness in subjects with primary ciliary dyskinesia. (CHEST 2000; 117:427‐ 433)

To examine whether children with a genetic predisposition to asthma are more likely to be afflicted with bronchiolitis, we studied 122 parents of infants who were hospitalized with the diagnosis of acute bronchiolitis (index group) and 120 parents of children who had never suffered from this disease (control group). The parents underwent bronchial challenge testing with methacholine and skin prick testing with common airborne allergens, and gave blood specimens for measurement of serum total IgE. There was no difference in atopic status, as assessed by the prevalence of atopy (at least one positive response to the allergens tested) or by serum total IgE levels, between index and control parents. The prevalence of bronchial hyperresponsiveness (BHR) (concentration of methacholine causing a 20% reduction in forced expiratory volume in 1 sec [PC20]18 mg/mL) was higher in index parents than in control parents (17.2% vs. 7.5%, p = 0.02). Bronchial responsiveness (BR) index was significantly higher in index parents than in control parents (1.135 +/- 0.088 vs. 1.104 +/- 0.071, p0.01). Parents of children who were hospitalized with acute bronchiolitis showed a higher level of BR, but not atopy. This suggests that in terms of BHR, there may be a genetic predisposition to the development of bronchiolitis.

The determinants of late asthmatic responses to exercise remain unknown. It has been reported that they may develop in some adult subjects with asthma following a late asthmatic response to allergen.We intended to corroborate this finding in children with asthma and to investigate which aspect of airway responses to allergen is associated with late asthmatic responses to exercise.We studied 17 children with allergic asthma, who showed late asthmatic responses to inhaled allergen (Dermatophagoides pteronyssinus). Each underwent an exercise challenge test two days before (pre-allergen) and two days after (postallergen) an allergen inhalation challenge. FEV1 was measured at regular intervals up to ten hours after each challenge. Methacholine PC20 was measured before the allergen challenge and before the postallergen exercise challenge.After the pre-allergen exercise test, all the subjects showed isolated early asthmatic responses. After the postallergen exercise test, seven showed dual responses (early and late asthmatic responses) (group I) and the remaining ten showed isolated early asthmatic responses (group II). Bronchial responses to pre-allergen exercise or inhaled allergen and the severity of early asthmatic responses to postallergen exercise were similar in groups I and II. Neither before allergen inhalation nor before the postallergen exercise was methacholine PC20 different between the two groups. Methacholine dose shift caused by allergen challenge, however, was significantly greater in group I than in group II (-2.00+/-0.39 versus -1.36+/-0.53 doubling doses; P.05). There was significant correlation between the dose shift and the magnitude of late response to the postallergen exercise in the whole group (r = 0.51, P.05).Late asthmatic responses to exercise may develop in some children with asthma following a late asthmatic response to allergen. This phenomenon was related neither to the baseline nor to postallergen methacholine PC20 but to the extent of increased sensitivity to methacholine caused by allergen challenge.