RESUMEN
Mutations in STXBP1 have recently been identified as a cause of infantile epileptic encephalopathy. The underlying mechanism of the disorder remains unclear and, recently, several case reports have described broad and progressive neurological phenotypes in addition to early-onset epilepsy. Herein, we describe a patient with early-onset epilepsy who subsequently developed a progressive neurological phenotype including parkinsonism in her early teens. A de novo mutation in STXBP1 (c.416C>T, p.(Pro139Leu)) was detected with exome sequencing together with profound impairment of complex I of the mitochondrial respiratory chain on muscle biopsy. These findings implicate a secondary impairment of mitochondrial function in the progressive nature of the disease phenotype.
Asunto(s)
Complejo I de Transporte de Electrón/deficiencia , Epilepsia/genética , Enfermedades Mitocondriales/genética , Proteínas Munc18/genética , Mutación Missense , Trastornos Parkinsonianos/genética , Encéfalo/fisiopatología , Niño , Progresión de la Enfermedad , Electroencefalografía , Complejo I de Transporte de Electrón/genética , Epilepsia/complicaciones , Exoma , Femenino , Humanos , Enfermedades Mitocondriales/complicaciones , Trastornos Parkinsonianos/complicaciones , FenotipoRESUMEN
This study seeks to determine whether minority Americans tend to see physicians of their own race as a matter of choice or simply because minority physicians are more conveniently located within predominantly minority communities. Using data from the Commonwealth Fund 1994 National Comparative Survey of Minority Health Care, we found that black and Hispanic Americans sought care from physicians of their own race because of personal preference and language, not solely because of geographic accessibility. As minority populations continue to grow, the demand for minority physicians is likely to increase. Keeping up with this demand will require medical school admissions policies and physician workforce planning to include explicit strategies to increase the supply of underrepresented minority physicians.
Asunto(s)
Etnicidad/estadística & datos numéricos , Aceptación de la Atención de Salud/psicología , Relaciones Médico-Paciente , Relaciones Raciales , Adulto , Negro o Afroamericano , Femenino , Accesibilidad a los Servicios de Salud , Hispánicos o Latinos , Humanos , Masculino , Persona de Mediana Edad , Aceptación de la Atención de Salud/estadística & datos numéricos , Estados Unidos , Población BlancaRESUMEN
BACKGROUND: There is increasing interest in the radial artery (RA) as a coronary artery bypass graft (CABG). However, few studies have examined the prevalence of pre-existing disease in this vessel. METHODS: Histological specimens from 177 RA were compared with 168 of internal mammary artery (IMA) and 86 of long saphenous vein (LSV) from the same patients undergoing CABG. The degree of stenosis, active atheroma, intimal thickening, and medial hyaline sclerosis was assessed. - RESULTS: 99% of IMAs, 98% of RAs and 100% of SVs had less than 30% stenosis. 91% of IMAs, 42% of RAs and 70% of SVs had less than 5% stenosis. Medial sclerosis was present in 10% of IMAs, 36% of LSVs and 46% of RAs. Medial calcification was present in 9% of RAs, 1% of LSVs and not in IMAs. CONCLUSION: The majority of conduits did not have evidence of severe disease. There is an increased prevalence of mild intimal thickening, medial sclerosis and medial calcification in RAs compared with IMAs and LSVs. The implications for longer-term graft patency are uncertain.
Asunto(s)
Arteriosclerosis/patología , Anastomosis Interna Mamario-Coronaria/métodos , Arteria Radial/patología , Arteria Radial/cirugía , Vena Safena/cirugía , Enfermedad Coronaria/patología , Enfermedad Coronaria/cirugía , Vasos Coronarios/patología , Vasos Coronarios/cirugía , Femenino , Supervivencia de Injerto , Humanos , Masculino , Arterias Mamarias/patología , Arterias Mamarias/cirugía , Persona de Mediana EdadRESUMEN
This article is about Karen, who was 20 weeks pregnant when she was involved in a gas explosion. The explosion caused a 35% body surface area deep partial-thickness burn to her legs and arms. This article focuses on the most important concerns and fears Karen expressed while she was in our care. Her statements triggered various clinical memories from several nurses in the burn unit, and thus the stories unfold. These stories reflect nursing practice through the psychological care, clinical signs, and pathophysiology of our patient. The spoken stories, coupled with the reflective stories, provide a total picture of the multidimensional care nurses provide for their patients.
Asunto(s)
Quemaduras/enfermería , Complicaciones del Embarazo/enfermería , Analgésicos/uso terapéutico , Actitud del Personal de Salud , Unidades de Quemados , Quemaduras/fisiopatología , Quemaduras/psicología , Quemaduras/terapia , Femenino , Humanos , Recién Nacido , Masculino , Dolor/tratamiento farmacológico , Dolor/fisiopatología , Embarazo , Complicaciones del Embarazo/fisiopatología , Complicaciones del Embarazo/psicología , Complicaciones del Embarazo/terapiaRESUMEN
Attitudes, knowledge, and personal factors related to circumcision in the newborn period were analyzed among a group of 92 randomly selected primary care physicians and 103 parents of male infants. Sixty-five percent of the physicians conveyed a positive attitude about routine neonatal circumcision to their patients; pediatricians were more likely to have a neutral attitude, and both family and general practitioners were more likely to encourage routine neonatal circumcision (P less than .01). Routine neonatal circumcision was favored more often by older, male, and circumcised physicians. Knowledge about the normal anatomy of the infants' foreskin was inadequate. Parents rarely perceived physicians as influential in the decision-making process (P less than .001). In contrast, fathers' circumcision status and parental belief in medical indications were positively related to the decision to circumcise (P less than .001 and P less than .01, respectively). The data suggest directions for change in clinical pediatric practice that may bring contemporary policy with regard to routine neonatal circumcision closer to actual practice.
Asunto(s)
Actitud del Personal de Salud , Actitud Frente a la Salud , Circuncisión Masculina , Recién Nacido , Adulto , Circuncisión Masculina/psicología , Toma de Decisiones , Medicina Familiar y Comunitaria , Padre/psicología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Obstetricia , Pediatría , Atención Primaria de Salud , Relaciones Profesional-Familia , Encuestas y CuestionariosAsunto(s)
Propelentes de Aerosoles , Hiperreactividad Bronquial/tratamiento farmacológico , Hidrocarburos Fluorados , Nebulizadores y Vaporizadores , Albuterol/administración & dosificación , Asma/tratamiento farmacológico , Estudios Cruzados , Método Doble Ciego , Humanos , Equivalencia TerapéuticaRESUMEN
The effect of acid etching on the surface appearance and flexural strength of four glass polyalkenoate cements was investigated. Specimens were etched for intervals of 10-60 s, both at the recommended time after mixing and after a 24-h delay. The surface texture was examined microscopically. Further specimens were subjected to a 4-point bend test following etching 1 h and 24 h after mixing. Deterioration of the surface appearance occurred as the etching time was increased beyond 10 s following immediate etching. Etching after 24 h reduced surface damage, but a 10-s etch still gave the most favourable surface appearance without loss of particulate material. Etching beyond 10 s significantly reduces flexural strength.
Asunto(s)
Grabado Ácido Dental , Cementos de Ionómero Vítreo/química , Silicatos de Aluminio/química , Cementos Cermet , Aleaciones Dentales/química , Pulido Dental , Elasticidad , Maleatos/química , Microscopía Electrónica de Rastreo , Plata/química , Estrés Mecánico , Propiedades de Superficie , Factores de TiempoRESUMEN
Allergy to house dust mites (HDM) and domestic pets is a major cause of asthma. People in developed countries spend more than 90% of their time indoors. We have measured levels of HDM allergen Der pI and cat allergen Fel dI in public buildings and public transport. Dust samples were collected by vacuuming a 1 m2 area for 2 min from five schools, six hotels, four cinemas, six pubs, three buses, two trains and 12 domestic households without a cat. Der pI and Fel dI were assayed with monoclonal antibodies in a two-site immunometric ELISA. Der pI concentration was significantly higher in the private homes than in comparable sites in public places except for cinema seats (where high values were found) compared with domestic sofas. Der pI > 2000 ng/g of fine dust was found in 30% of the upholstered seats, 9% having a concentration > 10,000 ng/g. Fel dI levels were significantly higher in the dust from upholstered seats (geometric mean 14.88 micrograms/g) than in carpeted floors (geometric mean 0.73 micrograms/g), and in public places than in private homes. Fel dI > 8 micrograms/g was found in 79% of the upholstered seats or furniture sampled in public buildings or public transport. In conclusion, upholstered seats from public buildings and public transport constitute an allergen reservoir for continuous contamination of the indoor environment which could compromise the effects of allergen avoidance employed at home.
Asunto(s)
Contaminación del Aire Interior/análisis , Alérgenos/análisis , Ambiente Controlado , Glicoproteínas/análisis , Ácaros , Contaminantes Atmosféricos/análisis , Animales , Anticuerpos Monoclonales , Antígenos Dermatofagoides , Gatos , Ensayo de Inmunoadsorción Enzimática , TransportesRESUMEN
CT-guided biopsy of pulmonary and mediastinal lesions is safe and effective. It is most valuable in those cases in which fluoroscopic guidance is not possible due to resolution or anatomic consideration. CT guidance permits puncture of lesions as small as 0.5 cm, typically not seen fluoroscopically. Sensitivity of biopsy in malignant lung lesions in our series of 83 cases was 92%. Pneumothorax is the most frequent complication (10-60%) and requires chest tube insertion in 5-15% of patients.
Asunto(s)
Biopsia con Aguja/métodos , Enfermedades Pulmonares/patología , Enfermedades del Mediastino/patología , Tomografía Computarizada por Rayos X , Biopsia con Aguja/instrumentación , Humanos , Enfermedades Pulmonares/diagnóstico por imagen , Enfermedades del Mediastino/diagnóstico por imagenRESUMEN
The frequency of cat and/or dog ownership in Ghana is comparable to that in the United Kingdom (approximately 50%). However, in Ghanaian communities pets are predominantly kept outdoors. Levels of pet allergens (Fel d 1 and Can f 1) in 100 Ghanaian homes (49 without pets) were compared with levels in 410 homes in the United Kingdom (258 without pets). Homes with pets in the United Kingdom contained much higher allergen levels than homes with pets in Ghana (for Fel d 1: mean difference, 275-fold; 95% CI, 129-fold to 594-fold; P <.0001; for Can f 1: mean difference, 75-fold; 95% CI, 33-fold to 169-fold; P <.0001). Homes without cats in the United Kingdom contained significantly higher levels of Fel d 1 than homes with cats in Ghana (mean difference, 3.7-fold; 95% CI, 2.0-fold to 7.2-fold; P <.0001). In the United Kingdom, homes with dogs contained 75-fold (95% CI, 47-fold to 139-fold) more Can f 1 than homes without dogs, whereas in Ghana, homes with dogs contained 3.1-fold (95% CI, 1.5-fold to 6.1-fold; P =.003) more Can f 1 than homes without dogs. In the United Kingdom, homes with cats contained 77-fold more Fel d 1 (95% CI, 46-fold to 129-fold; P <.0001) than homes without cats; there was no difference in cat allergen levels between homes with cats and homes without cats in Ghana. In conclusion, levels of pet allergens in Ghanaian homes with pets were (1) between 75-fold (dog) and 275-fold (cat) lower than levels in homes with pets in the United Kingdom and (2) lower than or comparable to levels in homes without pets in the United Kingdom.
Asunto(s)
Alérgenos/análisis , Animales Domésticos/inmunología , Exposición a Riesgos Ambientales , Vivienda , Animales , Antígenos de Plantas , Asma/etiología , Gatos , Países Desarrollados , Países en Desarrollo , Perros , Ghana , Glicoproteínas/análisis , Humanos , Reino Unido , Población UrbanaRESUMEN
Humidity is a decisive limiting factor for house dust mite (HDM) population growth and decreasing humidity may be the control method of choice. This study investigates the effects of portable dehumidifiers on the mite counts and concentration of the HDM allergen Der p I in the homes in northwest England. Mite counts and Der p I were measured in the paired dust samples collected by vacuuming a 1 m2 area of bedroom carpet, living room carpet, mattress and sofa for 2 min in six houses supplied with the dehumidifier and six control houses, before and 1, 2 and 3 months after the installment of dehumidifier. Temperature and relative humidity were recorded daily. There was no difference in mite counts in either of the groups throughout the study. Der p I decreased significantly in both groups and in all sampling sites, but no significant differences in the levels of reduction between the groups were found. Condensation was decreased in the dehumidifier group, but the level of indoor humidity capable of retarding mite population growth was not achieved. A single portable dehumidifier placed centrally in the house is unable to decrease indoor humidity to the level capable of retarding mite population growth and decreasing HDM allergens in the type of houses predominantly found in the northwest of England.
Asunto(s)
Polvo , Glicoproteínas , Humedad , Control de Ácaros y Garrapatas/instrumentación , Control de Ácaros y Garrapatas/métodos , Alérgenos , Antígenos Dermatofagoides , TemperaturaRESUMEN
BACKGROUND: House dust mite allergens play an important role in inducing IgE-mediated sensitization and the development of bronchial hyperresponsiveness (BHR) and asthma. This study investigated the relationship between mite allergen exposure and the clinical activity and severity of asthma. METHODS: Nonsmoking adult patients with asthma (n = 53) were randomly recruited from the asthma registry of two large family practitioner surgeries. Each participant underwent skin testing with common inhalant allergens, a methacholine bronchoprovocation test, and pulmonary function testing on up to 3 separate occasions over a 4-week period. BHR was expressed both as PD20 and dose-response ratio (DRR), and the patients with patients with PD20 of less than 12.25 mumol methacholine were classified as methacholine reactors. Patients were also asked to record peak expiratory flow rate (PEFR) values at 2-hour intervals during waking hours for 1 month. Daily PEFR variability was calculated as amplitude percent mean. Dust samples were collected by vacuuming bedding, bedroom carpets and mattresses. In addition, in the homes of 32 subjects with positive skin test responses to mites, airborne samples were taken overnight for 8 hours with a personal sampler attached to each subject's pillow. Der p 1 and Der p 2 levels were determined by a two-site monoclonal antibody-based ELISA. RESULTS: No difference in mite exposure was found between subjects who were sensitive to mites and those who were not. However, mite-sensitive methacholine reactors were exposed to significantly higher concentrations of Der p 1 in beds than mite-sensitive methacholine nonreactors (13.2 micrograms/gm and 1.45 micrograms/gm, respectively; p < 0.02). Der p 1 and Der p 2 were undetectable in 30 of 32 airborne samples. In mite-sensitive patients both Der p 1 and Der p 2 in beds significantly correlated with BHR (PD20: r = -0.49, DRR, r = 0.49; PD20: r = -0.46, DRR: r = 0.43) and amplitude percent mean PEFR (r = 0.38, r = 0.41) for Der p 1 and Der p 2, respectively. There was a significant negative correlation between exposure to Der p 1 and percent predicted FEV1 (r = -0.43). The correlation between Der p 2 and percent predicted FEV1 just failed to reach a significant level but showed a clear trend ( r = -0.35, p = 0.068). CONCLUSIONS: Clinical activity and severity of asthma (measured by the level of BHR, PEFR variability, and percent predicted FEV1) in mite-sensitive patients is related to exposure to mite allergens in the dust reservoir, with levels in bed being an important indicator that correlated with disease activity.
Asunto(s)
Contaminación del Aire Interior/efectos adversos , Alérgenos/efectos adversos , Asma/etiología , Polvo/efectos adversos , Glicoproteínas/inmunología , Ácaros/inmunología , Adulto , Animales , Antígenos Dermatofagoides , Asma/inmunología , Asma/fisiopatología , Femenino , Humanos , MasculinoRESUMEN
Eleven selected patients with obstructive jaundice underwent percutaneous cholecystostomy (PC) for decompression. Ten of these patients had the constellation of distal common duct obstruction, nondilated or minimally dilated intrahepatic ducts, and a distended gallbladder; one patient with a bleeding dyscrasia had moderately dilated intrahepatic bile ducts. All procedures were successful and effective, and 10 of 11 cholecystostomies were performed within 5-15 minutes. No specific complications occurred. The success, ease, and safety of the procedure indicate primary use of PC for biliary decompression when the intrahepatic bile ducts are minimally dilated or nondilated, because standard transhepatic biliary drainage may be difficult in these cases. Because cannulation of the cystic duct and hence internalization through the tumor may be difficult, PC may be most valuable preoperatively, or before standard percutaneous biliary drainage, or as an alternative to endoscopic drainage. This is a rapid and safe method with which to achieve biliary decompression, especially with minimally dilated or nondilated intrahepatic bile ducts.
Asunto(s)
Colecistostomía/métodos , Colestasis/cirugía , Adulto , Anciano , Cateterismo/métodos , Colestasis/diagnóstico , Colestasis/diagnóstico por imagen , Drenaje/métodos , Femenino , Humanos , Masculino , Persona de Mediana Edad , Punciones , Radiografía Intervencional , UltrasonografíaRESUMEN
BACKGROUND: Asthma is increasing in prevalence and severity in Africa. Previous studies have suggested that the prevalence of atopy in West Africa was low. OBJECTIVE: We sought to investigate the risk factors for asthma in Ghanaian school children. METHODS: Fifty children (age range, 9-16 years) with a physician diagnosis of asthma and asthma symptoms within the previous 12 months and 50 age- and sex-matched healthy control subjects were randomly selected and evaluated by means of questionnaire, skin testing, total and specific IgE measurements, and allergen level measurements from bed dust samples (mite, cat, dog, and cockroach). RESULTS: Asthmatic children were exposed to higher levels of mite allergens than were control children (geometric mean, 19 microg/g [95% CI, 13.6-26.5] vs. 11.2 microg/g [7.4-15.7]; P <.05). Cat and dog allergen levels were low. There was a marked dissociation between skin test responses and the presence of specific IgE to cat and dog (CAP method). However, 84% of subjects with positive cat dander-specific IgE levels in cat CAP tests and negative skin test responses did not have Fel d 1-specific IgE (chimeric ELISA). In the univariate analysis significant associations with the patient group were found for sensitization to mite (odds ratio [OR], 9.3; 95% CI, 3.7-23.4) and cockroach (OR, 3.9; 95% CI, 1.3-11.6), inner-city residence (OR, 3.5; 95% CI, 1.4-8.9), asthma in family member (OR, 3.5; 95% CI, 1.4-9.0), low (<5) position in sibship (OR, 3.6; 95% CI, 1.2-11), presence of smoker in home (OR, 3.7; 95% CI, 1.2-11.9), small household size (OR, 0.57; 95% CI, 0.35-0.93), and use of electricity as domestic fuel (OR, 0.34; 95% CI, 0.12-0.97). In the multivariate analysis sensitization to mites remained the strongest risk factor associated with the asthmatic group (OR, 10.4; 95% CI, 3.5-30.9). The other significant associations were inner-city residence (OR, 4.8; 95% CI, 1.5-5.2), sensitization to cockroach (OR, 4.9; 95% CI, 1.3-18.6), and position in sibship of less than 5 (OR, 6.3; 95% CI, 1.3-29.4). CONCLUSION: Sensitization to dust mite and cockroach allergens, inner-city residence, and low position in sibship were independent risk factors for asthma in Ghanaian children.
Asunto(s)
Asma/etiología , Adolescente , Alérgenos , Asma/epidemiología , Niño , Exposición a Riesgos Ambientales , Femenino , Ghana/epidemiología , Vivienda , Humanos , Hipersensibilidad Inmediata/diagnóstico , Inmunoglobulina E/sangre , Masculino , Análisis Multivariante , Factores de Riesgo , Pruebas Cutáneas , Población UrbanaRESUMEN
BACKGROUND: As more developing countries adopt a westernised style of living, an increase in the prevalence of asthma can be expected to occur in these areas. A study was undertaken to establish the normal response to exercise in Ghanaian children and to use these normal values to determine the prevalence of exercise induced bronchospasm (EIB) in urban rich (UR), urban poor (UP), and rural (R) school children. Skin test reactivity to common inhalant allergens in UR, UP, and R children with and without EIB was also investigated. METHODS: Two hundred children aged 9-16 years without a previous history of respiratory symptoms were randomly selected and underwent free running exercise testing. A normal response to exercise was defined as the group mean change in peak expiratory flow rate (PEFR) +/- 2 standard deviations. This value was used to identify the prevalence of EIB in UR, UP, and R schoolchildren. A total of 1095 children from three different schools underwent exercise testing (220 UP, 599 UR, 276 R), after which 916 children underwent skin prick testing to six common inhalant allergens (D farinae, D pteronyssinus, cat, dog, Aspergillus flavus and Candida albicans). RESULTS: From the results of exercise testing in asymptomatic children the normal range was defined as a fall in PEFR of < 12.5% after exercise. Thirty four children were classified as having EIB on the basis of the above definition, giving an overall prevalence of 3.1%. The prevalence of EIB was significantly higher in UR children (4.7%) than in both UP (2.2%; p < 0.05) and R children (1.4%; p < 0.01). However, the prevalence rates in the UP and R children were similar. The prevalence of atopy in the whole population was 4.4%. Of the children with EIB, 10% were skin test positive to at least one of the allergens tested. The prevalence of atopy was significantly higher in UR children (6.55%, 95% confidence interval (CI) 4.5% to 9.2%) than in UP (2.9%, 95% CI 0.9% to 6.7%) and R children (1.5%, 95% CI 0.4% to 3.7%), respectively (p < 0.005). CONCLUSIONS: The prevalence of EIB and atopy is higher in urban rich than in urban poor or rural children suggesting that, in addition to genetic predisposition, social and environmental factors such as wealth, life style, and housing are important determinants of these phenotypes.
Asunto(s)
Asma Inducida por Ejercicio/epidemiología , Población Rural , Población Urbana , Adolescente , Espasmo Bronquial/epidemiología , Niño , Femenino , Ghana/epidemiología , Humanos , Hipersensibilidad/epidemiología , Masculino , Prevalencia , Clase SocialRESUMEN
BACKGROUND: Sensitization and exposure to indoor allergens are the major risk factors for asthma. It is possible that significant exposure to domestic allergens occurs outside the home. OBJECTIVES: To investigate the levels of Can f 1 and Bla g 2 in the dust from carpeted floors and upholstered seats in public buildings and public transport and the airborne concentrations of Der p 1, Fel d 1, Can f 1 and Bla g 2 in schools and offices. METHODS: Can f 1 and Bla g 2 were measured in the dust collected by vacuuming a 1 m2 area of carpet, as well as upholstered seats in five schools, six hotels, four cinemas, six pubs, three buses and two trains. Dust was also collected from the bedroom carpet, living room carpet, mattress and sofa in 20 homes with and 20 homes without a dog in the same area. Personal airborne sampling (2 L/min) was conducted for 8 h in offices (n = 16) and classrooms (n = 9). In addition, airborne samples in schools were collected using a high volume pump (60 L/min) for 1 h in three classrooms immediately after the children vacated the school. Can f 1, Bla g 2, Der p 1 and Fel d 1 were assayed using a two-site monoclonal antibody-based ELISA. RESULTS: Can f 1 was detected in all dust samples from public places, ranging from 0.2 to 52.5 micrograms/g. Significantly higher levels were found in upholstered seats (geometric mean--GM 9.4 micrograms/g) than in carpets (GM 1.5 micrograms/g; P < 0.001), and levels of Can f 1 > 10 micrograms/g were found in 40% of upholstered seats in public places. Can f 1 was significantly higher in upholstered seats in public places than in sofas in homes without a dog (GM 1.8 micrograms/g; P < 0.001). Detectable levels of Bla g 2 were found in all of the schools (GM 2.4 U/g, range 0.8-4.4 U/g). Bla g 2 concentration greater than 2U/g (provisional threshold level representing risk of sensitization) was measured in 65% of the classrooms sampled. Der p 1 and Bla g 2 were below the detection limit in all airborne samples. However, airborne Fel d 1 and Can f 1 were detected in schools and offices, albeit in low concentrations. CONCLUSIONS: Upholstered seats from public places constitute a reservoir for the accumulation of dog allergen, and a source of exposure to Can f 1 inside public buildings or on public transport. Exposure to cockroach allergens in schools may be important for cockroach sensitized asthmatic children.
Asunto(s)
Contaminación del Aire Interior/análisis , Alérgenos/análisis , Exposición a Riesgos Ambientales/efectos adversos , Glicoproteínas/análisis , Salud Pública , Animales , Antígenos de Plantas , Ácido Aspártico Endopeptidasas , Gatos , Cucarachas/inmunología , Perros , Polvo , TransportesRESUMEN
It is widely believed that the mechanisms of action of outdoor air pollutants are the same as those found in the laboratory, although few studies have attempted to clarify this issue. This study investigates the relationship of asthmatic bronchial hyperresponsiveness (BHR), a marker of airway inflammation, and pulmonary function to ambient levels of summertime air pollution. Thirty eight nonsmoking adult asthmatic subjects underwent repeated measurement of methacholine BHR, using Yan's method, at differing levels of air pollution (O3, SO2, NO2, smoke) during summer 1993. A total of 109 evaluable tests were performed: 31 subjects completed three or more challenge tests, and seven managed two. Levels of all pollutants remained within current World Health Organization (WHO) Guidelines for Health. Changes in BHR were found to correlate significantly with changes in the levels of 24 h mean SO2, NO2 and smoke; 48 h mean NO2 and smoke; 24 h lag NO2; although the effect was only small, accounting for approximately 10% of the variability in within-subject BHR between visits. Twenty four hour lag NO2 was also associated with forced vital capacity (FVC). In conclusion, in subjects with asthma, methacholine bronchial hyperresponsiveness varies with ambient levels of summertime air pollution. This suggests that changes in airway inflammation underlie the increased respiratory morbidity known to accompany pollution episodes.