Dose-Response Effect of Saccharomyces cerevisiae UFMG A-905 on the Prevention of Asthma in an Animal Model.

Probiotics should be administered in adequate amounts to confer health benefits. Probiotic dose-response studies are still missing. Saccharomyces cerevisiae UFMG A-905 prevented asthma development; however, the ideal dose has not been investigated. We evaluated the optimal dose and administration regimen of S. cerevisiae UFMG A-905 in the prevention of asthma. Male Balb/c mice were sensitized intraperitoneally with ovalbumin (OVA) and challenged with OVA intranasally. Mice received, via gavage, daily or alternate-day S. cerevisiae UFMG A-905. In daily regimen, different concentrations (107, 108, or 109 CFU/mL) were given 10 days before OVA sensitization and during challenges. In alternate-day regimen, a concentration of 109 CFU/mL was administered three times per week for 5 weeks, starting 2 weeks prior to the first sensitization. After the last challenge, in vivo bronchial hyperresponsiveness and airway and lung inflammation were assessed. OVA-challenged mice, when compared to saline-challenged mice, presented a significant increase in bronchial hyperresponsiveness and airway and lung inflammation. Daily and alternate-day administration of 109 CFU/mL of S. cerevisiae UFMG A-905 significantly reduced bronchial hyperresponsiveness; lower concentrations of S. cerevisiae UFMG A-905 did not significantly reduce bronchial hyperresponsiveness. Daily regimen with the highest concentration significantly reduced total cell number, eosinophil count in the BAL, and the levels of IL-4, IL-5, and IL-13. Daily administration of S. cerevisiae UFMG A-905 at 107 and 108 CFU/mL and alternate-day regimen did not significantly decrease airway and lung inflammation. S. cerevisiae UFMG A-905 led to a significant attenuation of bronchial hyperresponsiveness and lung inflammation in a dose-dependent manner.

The impact of an enhanced health surveillance system for COVID-19 management in Serrana, Brazil.

Objective: To describe the successful implementation of an enhanced public health surveillance system based on early detection, tracing contacts, and patient follow-up and support. Study design: A prospective observational cohort study conducted in Serrana, São Paulo State, Brazil. Methods: The implementation was based on four axes: increasing the access to SARS-CoV-2 testing; correct swab collection; testing patients with mild symptoms; and patient follow-up. Positivity rate, patient demographic and clinical characteristics, dynamics of disease severity, SARS-CoV-2 genome evolution, and the impact on COVID-19 research were assessed from August 23, 2020 to February 6, 2021 (between epidemiological week 35/2020 and 5/2021, a total of 24 weeks). Results: The number of sites collecting rt-PCR for SARS-CoV-2 was increased from one to seven points and staff was trained in the correct use of personal protective equipment and in the swab collection technique. During the study period, 6728 samples were collected from 6155 participants vs. 2770 collections in a similar period before. SARS-CoV-2 RNA was detected in 1758 (26.1%) swabs vs. 1117 (36.7%) before the implementation of the surveillance system (p < 0.001). Positivity rates varied widely between epidemiological weeks 35/2020 and 5/2021 (IQR, 12.8%-31.3%). Out of COVID-19 patients, 91.1% were adults at a median age of 35 years (IQR, 25-50 years), 42.6% were men and 57.4% were women, with a SARS-CoV-2 positivity rate of 28.6% and 24.4% (p < 0.001), respectively. The most common symptoms were headache (72.6%), myalgia (65.0%), and cough (61.7%). Comorbidities were found in 20.8% of patients, the most common being hypertension and diabetes. According to the World Health Organization clinical progression scale, 93.5% of patients had mild disease, 1.6% were hospitalized with moderate disease, 3.2% were hospitalized with severe disease, and 1.4% died. The enhanced surveillance system led to the development of COVID-19 related research. Conclusions: The enhanced surveillance system in Serrana improved COVID-19 understanding and management. By integrating community and academic institutions, it was possible to monitor SARS-CoV-2 positive cases and variants, follow the epidemic trend, guide patients, and develop relevant research projects.

Early Neuromuscular Electrical Stimulation in Addition to Early Mobilization Improves Functional Status and Decreases Hospitalization Days of Critically Ill Patients.

OBJECTIVES: To evaluate the impact of the additional use of early neuromuscular electrical stimulation (NMES) on an early mobilization (EM) protocol. DESIGN: Randomized controlled trial. SETTING: ICU of the Clinical Hospital of Ribeirão Preto, University of São Paulo, Brazil. PATIENTS: One hundred and thirty-nine consecutive mechanically ventilated patients were included in the first 48 hours of ICU admission. INTERVENTIONS: The patients were divided into two groups: EM and EM+NMES. Both groups received EM daily. In the EM+NMES group, patients additionally received NMES 5 days a week, for 60 minutes, starting in the first 48 hours of ICU admission until ICU discharge. MEASUREMENTS AND MAIN RESULTS: Functional status, muscle strength, ICU and hospital length of stay (LOS), frequency of delirium, days on mechanical ventilation, mortality, and quality of life were assessed. Patients in the EM+NMES group presented a significant higher score of functional status measured by the Functional Status Score for the ICU scale when compared with the EM group in the first day awake: 22 (15-26) versus 12 (8-22) (p = 0.019); at ICU discharge: 28 (21-33) versus 18 (11-26) (p = 0.004); and hospital discharge: 33 (27-35) versus 25 (17-33) (p = 0.014), respectively. They also had better functional status measured by the Physical Function Test in the ICU scale, took less days to stand up during the ICU stay, and had a significant shorter hospital LOS, lower frequency of ICU-acquired weakness, and better global muscle strength. CONCLUSIONS: The additional application of early NMES promoted better functional status outcomes on the first day awake and at ICU and hospital discharge. The patients in the EM+NMES group also took fewer days to stand up and had shorter hospital LOS, lower frequency of ICU-acquired weakness, and better muscle strength. Future studies are still necessary to clarify the effects of therapies associated with EM, especially to assess long-term outcomes.

Efficacy of COVID-19 outbreak management in a skilled nursing facility based on serial testing for early detection and control.

SARS-CoV-2 has a high risk of outbreak in long-term skilled nursing facilities (SNF). Coronavirus disease (COVID-19) has high mortality rates among the elderly with chronic health conditions. Following identification of COVID-19 index case in a SNF, serial point-prevalence was implemented with reverse transcription-polymerase chain reaction (RT-PCR) and immunochromatographic assays. Active surveillance and early isolation of infected patients were implemented. Out of 23 SNF residents and 26 healthcare workers (HCW), 18 (78%) and 12 (46%) tested positive for SARS-CoV-2, respectively. High proportion (38%) of positive patients were asymptomatic and RT-PCR was positive up to six days before symptoms. Five (21.74%) residents were hospitalized with COVID-19, and 2 (9%) died; only 1 (4%) HCW needed to be hospitalized and no staff members died. Active surveillance helped COVID-19 control and management in a SNF. Testing symptomatic individuals only may fail to identify and isolate all persons contributing to transmission. In high-risk elderly, only symptoms screening may not be enough for outbreak control.

Beneficial effects of colchicine for moderate to severe COVID-19: a randomised, double-blinded, placebo-controlled clinical trial.

OBJECTIVE: To evaluate whether the addition of colchicine to standard treatment for COVID-19 results in better outcomes. DESIGN: We present the results of a randomised, double-blinded, placebo-controlled clinical trial of colchicine for the treatment of moderate to severe COVID-19, with 75 patients allocated 1:1 from 11 April to 30 August 2020. Colchicine regimen was 0.5 mg thrice daily for 5 days, then 0.5 mg twice daily for 5 days. The primary endpoints were the need for supplemental oxygen, time of hospitalisation, need for admission and length of stay in intensive care unit and death rate. RESULTS: Seventy-two patients (36 for placebo and 36 for colchicine) completed the study. Median (and IQR) time of need for supplemental oxygen was 4.0 (2.0-6.0) days for the colchicine group and 6.5 (4.0-9.0) days for the placebo group (p<0.001). Median (IQR) time of hospitalisation was 7.0 (5.0-9.0) days for the colchicine group and 9.0 (7.0-12.0) days for the placebo group (p=0.003). At day 2, 67% versus 86% of patients maintained the need for supplemental oxygen, while at day 7, the values were 9% versus 42%, in the colchicine and the placebo groups, respectively (log rank; p=0.001). Two patients died, both in placebo group. Diarrhoea was more frequent in the colchicine group (p=0.26). CONCLUSION: Colchicine reduced the length of both, supplemental oxygen therapy and hospitalisation. The drug was safe and well tolerated. Once death was an uncommon event, it is not possible to ensure that colchicine reduced mortality of COVID-19. TRIAL REGISTRATION NUMBER: RBR-8jyhxh.

Aqueous Pyrostegia venusta (Ker Gawl.) Miers extract attenuates allergen-induced asthma in a mouse model via an antioxidant mechanism.

Objective:Pyrostegia venusta (Ker-Gawl.) Miers (Bignoniaceae) is a perennial invasive vine, distributed worldwide. In folk medicine, its parts are used for the treatment of inflammatory respiratory diseases. Extracts of P. venusta have antioxidant, antimicrobial, and antinociceptive properties. The aim of this study was to evaluate the effects of two extracts (aqueous and hydroethanolic) of P. venusta in the treatment of asthma in an animal model.Methods: Balb/c mice were sensitized twice with ovalbumin (OVA) intraperitoneally (ip), one week apart, and after one week, challenged with OVA intranasally on four alternate days. Mice were treated ip with 300 mg/kg of aqueous or hydroethanolic extracts for seven consecutive days. Control groups received saline on the same days. Bronchial hyperresponsiveness, production of Th1 and Th2 cytokines, lung and airway inflammation, and antioxidant activity in lung tissue were assessed.Results: Treatment with aqueous extract significantly decreased bronchial hyperresponsiveness, measured by total and tissue resistance and elastance. The administration of hydroethanolic extract did not reduce bronchial hyperresponsiveness. In addition, both extracts significantly reduced total cell and eosinophil counts in bronchoalveolar lavage. Both extracts did not change significantly IL-4, IL-5, IL-9, IL-13, IFN-gamma, and TGF-beta levels. Of note, only the aqueous extract significantly increased the total antioxidant activity and reduced lung inflammation.Conclusion: Aqueous extract of P. venusta reduced bronchial hyperresponsiveness, lung and airway inflammation, probably via an antioxidant mechanism. These results demonstrate that P. venusta may have potential for asthma treatment.

Crotoxin-Induced Mice Lung Impairment: Role of Nicotinic Acetylcholine Receptors and COX-Derived Prostanoids.

Respiratory compromise in Crotalus durissus terrificus (C.d.t.) snakebite is an important pathological condition. Considering that crotoxin (CTX), a phospholipase A2 from C.d.t. venom, is the main component of the venom, the present work investigated the toxin effects on respiratory failure. Lung mechanics, morphology and soluble markers were evaluated from Swiss male mice, and mechanism determined using drugs/inhibitors of eicosanoids biosynthesis pathway and autonomic nervous system. Acute respiratory failure was observed, with an early phase (within 2 h) characterized by enhanced presence of eicosanoids, including prostaglandin E2, that accounted for the increased vascular permeability in the lung. The alterations of early phase were inhibited by indomethacin. The late phase (peaked 12 h) was marked by neutrophil infiltration, presence of pro-inflammatory cytokines/chemokines, and morphological alterations characterized by alveolar septal thickening and bronchoconstriction. In addition, lung mechanical function was impaired, with decreased lung compliance and inspiratory capacity. Hexamethonium, a nicotinic acetylcholine receptor antagonist, hampered late phase damages indicating that CTX-induced lung impairment could be associated with cholinergic transmission. The findings reported herein highlight the impact of CTX on respiratory compromise, and introduce the use of nicotinic blockers and prostanoids biosynthesis inhibitors as possible symptomatic therapy to Crotalus durissus terrificus snakebite.

Galectin-3 aggravates experimental polymicrobial sepsis by impairing neutrophil recruitment to the infectious focus.

Sepsis is an overwhelming systemic inflammation resulting from an uncontrolled infection that causes extensive tissue damage, organ dysfunction and eventually death. A growing body of evidence indicates that impaired neutrophil migration to the site of infection is associated with poor outcome in sepsis. Here we show that galectin-3 (Gal-3), an endogenous glycan-binding protein, plays a critical role in sepsis outcome. We found that serum Gal-3 concentration increased in patients with septic shock and mice undergoing sepsis induced by cecal ligation and puncture (CLP). Mice deficient in Gal-3 (Gal-3 KO) are more resistant to sepsis induced by CLP, showing lower levels of biochemical markers and neutrophil infiltration for organ injury/dysfunction than those observed in wild-type mice (WT). Furthermore, Gal-3 KO mice show an increased number of neutrophils in the primary focus of infection and reduced bacterial loads in the peritoneal cavity, blood, and lungs. Mechanistically, blood neutrophils from septic mice show higher levels of surface-bound Gal-3 than neutrophils from naive mice. The deficiency of Gal-3 was associated with increased rolling and adhesion of these cells in mesenteric venules. Our results indicate that Gal-3, secreted during sepsis, inhibits neutrophil migration into the infectious focus, which promotes the bacterial spread and worsens the outcome of sepsis.

Chronic Toxoplasma gondii Infection Exacerbates Secondary Polymicrobial Sepsis.

Sepsis is a severe syndrome that arises when the host response to an insult is exacerbated, leading to organ failure and frequently to death. How a chronic infection that causes a prolonged Th1 expansion affects the course of sepsis is unknown. In this study, we showed that mice chronically infected with Toxoplasma gondii were more susceptible to sepsis induced by cecal ligation and puncture (CLP). Although T. gondii-infected mice exhibited efficient control of the bacterial burden, they showed increased mortality compared to the control groups. Mechanistically, chronic T. gondii infection induces the suppression of Th2 lymphocytes via Gata3-repressive methylation and simultaneously induces long-lived IFN-γ-producing CD4+ T lymphocytes, which promotes systemic inflammation that is harmful during CLP. Chronic T. gondii infection intensifies local and systemic Th1 cytokines as well as nitric oxide production, which reduces systolic and diastolic arterial blood pressures after sepsis induction, thus predisposing the host to septic shock. Blockade of IFN-γ prevented arterial hypotension and prolonged the host lifespan by reducing the cytokine storm. Interestingly, these data mirrored our observation in septic patients, in which sepsis severity was positively correlated to increased levels of IFN-γ in patients who were serologically positive for T. gondii. Collectively, these data demonstrated that chronic infection with T. gondii is a critical factor for sepsis severity that needs to be considered when designing strategies to prevent and control the outcome of this devastating disease.

IL-33 contributes to sepsis-induced long-term immunosuppression by expanding the regulatory T cell population.

Patients who survive sepsis can develop long-term immune dysfunction, with expansion of the regulatory T (Treg) cell population. However, how Treg cells proliferate in these patients is not clear. Here we show that IL-33 has a major function in the induction of this immunosuppression. Mice deficient in ST2 (IL-33R) develop attenuated immunosuppression in cases that survive sepsis, whereas treatment of naive wild-type mice with IL-33 induces immunosuppression. IL-33, released during tissue injury in sepsis, activates type 2 innate lymphoid cells, which promote polarization of M2 macrophages, thereby enhancing expansion of the Treg cell population via IL-10. Moreover, sepsis-surviving patients have more Treg cells, IL-33 and IL-10 in their peripheral blood. Our study suggests that targeting IL-33 may be an effective treatment for sepsis-induced immunosuppression.

Asthma self-management model: randomized controlled trial.

Information for patients provided by the pharmacist is reflected in adhesion to treatment, clinical results and patient quality of life. The objective of this study was to assess an asthma self-management model for rational medicine use. This was a randomized controlled trial with 60 asthmatic patients assigned to attend five modules presented by a pharmacist (intervention group) and 59 patients in the control group. Data collection was performed before and after this 4-month intervention and included an evaluation of asthma knowledge, lifestyle, inhaler techniques, adhesion to treatment, pulmonary function and quality of life. An economic viability analysis was also performed. The intervention group obtained an increase in asthma knowledge scores of 58.3-79.5% (P < 0.001). In this group, there was also an increase in the number of individuals who practiced physical exercise (36-43%), in the number of correct replies regarding the use of inhalers, in the percentage of adherent patients, and in quality of life scores for all domains. We concluded that this asthma self-management model was effective in improving the quality of life of asthma patients.

Aprendizado baseado em problemas / Problem-based learning

A Aprendizagem Baseada em Problemas (ABP), introduzida no ensino de Ciências da Saúde na McMaster University, Canadá, em 1969, é uma proposta pedagógica que consiste no ensino centrado no estudante e baseado na solução de problemas, reais ou simulados. Os alunos, para solucionar esse problema,recorrem aos conhecimentos prévios, discutem, estudam, adquirem e integram os novos conhecimentos.Essa integração, aliada à aplicação prática, facilita a retenção do conhecimento. Portanto, a ABP valoriza, além do conteúdo a ser aprendido, a forma como ocorre o aprendizado, reforçando o papel ativo do aluno neste processo, permitindo que ele aprenda como aprender. A ABP oferece diversas vantagens, como o desenvolvimento da autonomia, a interdisciplinaridade, a indissociabilidade entre teoria e prática,o desenvolvimento do raciocínio crítico e de habilidades de comunicação, e a educação permanente. Porém, para a sua utilização são necessários investimentos em recursos humanos e materiais, além de um programa de capacitação de professores e alunos bem estruturado, que devem sempre ser considerados antes de sua implementação.

The Problem-Based Learning (PBL), introduced at McMaster University School of Medicine, Canada, in 1969, is a student-centered pedagogical approach based on critical thinking and problem solving. In order to solve a problem, students use their prior knowledge, discuss, study, acquire and integrate new information. This learning integration, combined with a practical application, facilitates knowledge retention.Therefore, students become actively involved in the learning process and improve the capacity of learn how to learn. PBL has several advantages, such as, it stimulates the development of autonomy on learning; interdisciplinary; integration of knowledge and practice; development of teamwork, critical thinking and communication skills; and continuing education. However, to be able to implement PBL on curriculum, it’s necessary investments in human and material resources, including a well-structured training program for teachers and students.

Avaliação formativa e feedback como ferramenta de aprendizado na formação de profissionais da saúde / Formative assessment and feedback as learning tools in health professions education

As diferentes formas de avaliação são elementos centrais do processo de ensino-aprendizagem de qualquer programa educacional, e devem ser bem planejadas e implementadas em todas as propostas curriculares,especialmente na formação de profissionais na área da saúde. Uma avaliação do estudante adequada e de qualidade guarda estreita relação com a competência e capacitação do profissional que será entregue à sociedade. Neste contexto, a avaliação formativa e a capacitação dos professores para prover feedback efetivo, frequente, e de qualidade são fundamentais na formação dos futuros profissionais da saúde. Este artigo faz uma revisão sobre avaliação formativa, feedback e debriefing.

The different assessment forms are major elements of any teaching and learning process in educational programs, and should be considered as a core component to be planned and implemented in all curriculums, especially in the health professions education. A regular and qualified students’ assessment is closely related to competence and skills of the professionals that will be delivered to society. In this context, formative assessment and well-trained staff to provide effective and regular feedback are essentials in the formation of the future generation of health professionals. This article focuses primarily on formative assessment, feedback and debriefing.

Laboratory animals and respiratory allergies: the prevalence of allergies among laboratory animal workers and the need for prophylaxis.

OBJECTIVE: Subjects exposed to laboratory animals are at a heightened risk of developing respiratory and allergic diseases. These diseases can be prevented by simple measures such as the use of personal protective equipment. We report here the primary findings of the Laboratory Animals and Respiratory Allergies Study regarding the prevalence of allergic diseases among laboratory animal workers, the routine use of preventive measures in laboratories and animal facilities, and the need for prevention programs. METHODS: Animal handlers and non-animal handlers from 2 Brazilian universities (University of São Paulo and State University of Campinas) answered specific questionnaires to assess work conditions and symptoms. These subjects also underwent spirometry, a bronchial challenge test with mannitol, and skin prick tests for 11 common allergens and 5 occupational allergens (rat, mouse, guinea pig, hamster, and rabbit). RESULTS: Four hundred fifty-five animal handlers (32±10 years old [mean±SD], 209 men) and 387 non-animal handlers (33±11 years old, 121 men) were evaluated. Sensitization to occupational allergens was higher among animal handlers (16%) than non-animal handlers (3%, p<0.01). Accessibility to personal protective equipment was measured at 85% (median, considering 73 workplaces of the animal handler group). Nineteen percent of the animal handlers indicated that they wear a respirator at all times while handling animals or working in the animal room, and only 25% of the animal handlers had received an orientation about animal-induced allergies, asthma, or rhinitis. CONCLUSION: In conclusion, our data indicate that preventive programs are necessary. We suggest providing individual advice to workers associated with institutional programs to promote a safer work environment.

Laboratory animals and respiratory allergies: The prevalence of allergies among laboratory animal workers and the need for prophylaxis

OBJECTIVE: Subjects exposed to laboratory animals are at a heightened risk of developing respiratory and allergic diseases. These diseases can be prevented by simple measures such as the use of personal protective equipment. We report here the primary findings of the Laboratory Animals and Respiratory Allergies Study regarding the prevalence of allergic diseases among laboratory animal workers, the routine use of preventive measures in laboratories and animal facilities, and the need for prevention programs. METHODS: Animal handlers and non-animal handlers from 2 Brazilian universities (University of São Paulo and State University of Campinas) answered specific questionnaires to assess work conditions and symptoms. These subjects also underwent spirometry, a bronchial challenge test with mannitol, and skin prick tests for 11 common allergens and 5 occupational allergens (rat, mouse, guinea pig, hamster, and rabbit). RESULTS: Four hundred fifty-five animal handlers (32±10 years old [mean±SD], 209 men) and 387 non-animal handlers (33±11 years old, 121 men) were evaluated. Sensitization to occupational allergens was higher among animal handlers (16%) than non-animal handlers (3%, p<0.01). Accessibility to personal protective equipment was measured at 85% (median, considering 73 workplaces of the animal handler group). Nineteen percent of the animal handlers indicated that they wear a respirator at all times while handling animals or working in the animal room, and only 25% of the animal handlers had received an orientation about animal-induced allergies, asthma, or rhinitis. CONCLUSION: In conclusion, our data indicate that preventive programs are necessary. We suggest providing individual advice to workers associated with institutional programs to promote a safer work environment. .

Clinical evaluation of the NS1 antigen-capture ELISA for early diagnosis of dengue virus infection in Brazil.

The fact that the diagnosis of infection with dengue virus is usually made by detecting IgM antibodies during the convalescent phase of the disease interferes with disease management and, consequently, with reducing mortality rates. This study evaluated the sensitivity and specificity of detection of NS1 in samples of patients suspected of acute dengue virus infection in Brazil. The results were used to institute treatment and the sensitivity and specificity of detection of NS1 were compared to the results of detection of IgM, virus isolation, and RT-PCR. Detection of NS1 yielded better results than RT-PCR and virus isolation. When considering IgM detection and RT-PCR positive results as "gold standards," the sensitivity and specificity of the NS1 assay were 95.9% and 81.1%, respectively. All patients enrolled in the study were treated promptly and had an uneventful course of the disease. The detection of NS1 provided better results than the diagnostic techniques used currently during the acute phase of disease (RT-PCR and virus isolation). Detection of NS1 is an important tool for the diagnosis of acute dengue infection, particularly in highly endemic areas, allowing for rapid treatment of patients and reduction of disease burden.

Influence of nocturnal asthma on chronotype.

Individual differences in circadian rhythm have been studied since the past century. Chronotypes are a chronobiology classification based on the preferential times for beginning and ending activities throughout the day. Chronotypes can be classified as definitely morning, moderately morning, indifferent, moderately evening, and definitely evening. We aim to assess the distribution of chronotypes in asthmatics and the relationship of chronotype to the presence of nocturnal symptoms. Two hundred subjects were evaluated, 100 asthmatics and 100 non-asthmatics. The Morningness/Eveningness questionnaire was applied for chronotype determination. The asthmatics were subdivided according to the presence or absence of nocturnal symptoms. The chronotype distribution did not differ significantly between asthmatics and non-asthmatics. Thirty-five percent of the asthma group reported nocturnal symptoms. There was a significant difference in chronotype distribution between asthmatics with and without nocturnal worsening. The asthmatics with nocturnal symptoms had a lower prevalence of morning types and had a greater predominance of indifferent chronotype compared to asthmatics without nocturnal symptoms (p = 0.011). In conclusion, asthmatics with nocturnal symptoms present deviation from the chronotype distribution curve when compared to asthmatics without nocturnal symptoms. This is the first study to show the effect of a disease on chronotypes.

Comparison of 4 AM and 4 PM bronchial responsiveness to hypertonic saline in asthma.

Bronchial responsiveness to methacholine or histamine increases at night and may contribute to the mechanisms of nocturnal asthma. Hypertonic saline (HS) is a more clinically relevant stimulus for the diagnosis and assessment of the severity of asthma, but the circadian variation in bronchial responsiveness to hypertonic challenges has not been addressed. The aim of this study was to compare the responsiveness to hypertonic saline at 4:00 AM and at 4:00 PM. Eighteen diurnally active patients (11 women) with asthma, 31 +/- 9 years of age (mean +/- SD) and with a forced expiratory volume in 1 s (FEV(1)) of 79.11% +/- 12.85%, underwent two challenge tests (4:00 AM and 4:00 PM) in random sequence separated by an interval of 7 days. The challenge test consisted of inhalations of 4.5% saline with increasing doses by doubling the duration of nebulization (0.5, 1, 2, 4, and 8 min). The inhalation continued until a drop of 20% in FEV(1) was achieved or total time of 15.5 min. The provocative dose that caused the 20% drop in FEV(1) (PD(20)) was calculated. Differences were found between 4:00 PM and 4:00 AM values for inhalation times [3.80 +/- 3.57 min and 2.19 +/- 2.42 min (p = 0.001), respectively] and for PD(20) [4.94 +/- 6.77 ml and 2.93 +/- 4.74 ml (p = 0.002), respectively]. Eight patients with a home-assessed nocturnal peak expiratory flow (PEF) drop of more than 15% formed the nocturnal asthma group. The behavior of these patients was similar to that of the non-nocturnal asthma group. We conclude that the bronchial responsiveness to HS increases at night.