Characteristics and Outcomes of Pregnant Women Hospitalized With Laboratory-Confirmed Respiratory Syncytial Virus Before and During the COVID-19 Pandemic.

Background: Respiratory syncytial virus (RSV) can cause severe disease among infants and older adults. Less is known about RSV among pregnant women. Methods: To analyze hospitalizations with laboratory-confirmed RSV among women aged 18 to 49 years, we used data from the RSV Hospitalization Surveillance Network (RSV-NET), a multistate population-based surveillance system. Specifically, we compared characteristics and outcomes among (1) pregnant and nonpregnant women during the pre-COVID-19 pandemic period (2014-2018), (2) pregnant women with respiratory symptoms during the prepandemic and pandemic periods (2021-2023), and (3) pregnant women with and without respiratory symptoms in the pandemic period. Using multivariable logistic regression, we examined whether pregnancy was a risk factor for severe outcomes (intensive care unit admission or in-hospital death) among women aged 18 to 49 years who were hospitalized with RSV prepandemic. Results: Prepandemic, 387 women aged 18 to 49 years were hospitalized with RSV. Of those, 350 (90.4%) had respiratory symptoms, among whom 33 (9.4%) were pregnant. Five (15.2%) pregnant women and 74 (23.3%) nonpregnant women were admitted to the intensive care unit; no pregnant women and 5 (1.6%) nonpregnant women died. Among 279 hospitalized pregnant women, 41 were identified prepandemic and 238 during the pandemic: 80.5% and 35.3% had respiratory symptoms, respectively (P < .001). Pregnant women were more likely to deliver during their RSV-associated hospitalization during the pandemic vs the prepandemic period (73.1% vs 43.9%, P < .001). Conclusions: Few pregnant women had severe RSV disease, and pregnancy was not a risk factor for a severe outcome. More asymptomatic pregnant women were identified during the pandemic, likely due to changes in testing practices for RSV.

Diversity, Equity, and Inclusion in the Pediatric Pulmonary Workforce: An Official American Thoracic Society Workshop Report.

Despite growing recognition of the need for increased diversity among students, trainees, and faculty in health care, the medical workforce still lacks adequate representation from groups historically underrepresented in medicine (URiM). The subspecialty field of pediatric pulmonology is no exception. Although there have been efforts to address issues of diversity, equity, and inclusion (DEI) in our own field, gaps persist. To address these gaps, the members of the Diversity, Equity, and Inclusion Advisory Group (DEI-AG) of the American Thoracic Society Pediatrics Assembly created and distributed a Needs Assessment Survey in the United States and Canada to better understand the racial and ethnic demographics of the pediatric pulmonary workforce and to learn more about successes, gaps, and opportunities to enhance how we recruit, train, and retain a diverse workforce. The DEI-AG leadership cochairs convened a workshop to review the findings of the DEI Needs Assessment Survey and to develop strategies to improve the recruitment and retention of URiM fellows and faculty. This Official ATS Workshop Report aims to identify barriers and opportunities for recruitment, training, and career development within the field of pediatric pulmonology. Additionally, we offer useful strategies and resources to improve the recruitment of URiM residents, the mentorship of trainees and junior faculty, and the career development of URiM faculty in academic centers. This Workshop Report is an important first deliverable by the DEI-AG. We hope that this work, originating from within the Pediatrics Assembly, will serve as a model for other Assemblies, disciplines across the ATS, and other fields in Pediatrics.

Racial and Ethnic Disparities in Rates of COVID-19-Associated Hospitalization, Intensive Care Unit Admission, and In-Hospital Death in the United States From March 2020 to February 2021.

Importance: Racial and ethnic minority groups are disproportionately affected by COVID-19. Objectives: To evaluate whether rates of severe COVID-19, defined as hospitalization, intensive care unit (ICU) admission, or in-hospital death, are higher among racial and ethnic minority groups compared with non-Hispanic White persons. Design, Setting, and Participants: This cross-sectional study included 99 counties within 14 US states participating in the COVID-19-Associated Hospitalization Surveillance Network. Participants were persons of all ages hospitalized with COVID-19 from March 1, 2020, to February 28, 2021. Exposures: Laboratory-confirmed COVID-19-associated hospitalization, defined as a positive SARS-CoV-2 test within 14 days prior to or during hospitalization. Main Outcomes and Measures: Cumulative age-adjusted rates (per 100 000 population) of hospitalization, ICU admission, and death by race and ethnicity. Rate ratios (RR) were calculated for each racial and ethnic group compared with White persons. Results: Among 153 692 patients with COVID-19-associated hospitalizations, 143 342 (93.3%) with information on race and ethnicity were included in the analysis. Of these, 105 421 (73.5%) were 50 years or older, 72 159 (50.3%) were male, 28 762 (20.1%) were Hispanic or Latino, 2056 (1.4%) were non-Hispanic American Indian or Alaska Native, 7737 (5.4%) were non-Hispanic Asian or Pacific Islander, 40 806 (28.5%) were non-Hispanic Black, and 63 981 (44.6%) were White. Compared with White persons, American Indian or Alaska Native, Latino, Black, and Asian or Pacific Islander persons were more likely to have higher cumulative age-adjusted rates of hospitalization, ICU admission, and death as follows: American Indian or Alaska Native (hospitalization: RR, 3.70; 95% CI, 3.54-3.87; ICU admission: RR, 6.49; 95% CI, 6.01-7.01; death: RR, 7.19; 95% CI, 6.47-7.99); Latino (hospitalization: RR, 3.06; 95% CI, 3.01-3.10; ICU admission: RR, 4.20; 95% CI, 4.08-4.33; death: RR, 3.85; 95% CI, 3.68-4.01); Black (hospitalization: RR, 2.85; 95% CI, 2.81-2.89; ICU admission: RR, 3.17; 95% CI, 3.09-3.26; death: RR, 2.58; 95% CI, 2.48-2.69); and Asian or Pacific Islander (hospitalization: RR, 1.03; 95% CI, 1.01-1.06; ICU admission: RR, 1.91; 95% CI, 1.83-1.98; death: RR, 1.64; 95% CI, 1.55-1.74). Conclusions and Relevance: In this cross-sectional analysis, American Indian or Alaska Native, Latino, Black, and Asian or Pacific Islander persons were more likely than White persons to have a COVID-19-associated hospitalization, ICU admission, or in-hospital death during the first year of the US COVID-19 pandemic. Equitable access to COVID-19 preventive measures, including vaccination, is needed to minimize the gap in racial and ethnic disparities of severe COVID-19.

The perfect storm: A case of COVID-19 infection in an adolescent patient with EVALI.

COVID-19 and EVALI share imaging findings and clinical features, including fever, respiratory, and gastrointestinal symptoms. To our knowledge, the clinical picture in patients presenting with both conditions simultaneously has not been reported. We present the case of a 17-year-old male with COVID-19 and EVALI, his hospital course, and clinical outcome.

The M4 insulator, the TM2 matrix attachment region, and the double copy of the heavy chain gene contribute to the enhanced accumulation of the PHB-01 antibody in tobacco plants.

The expression of recombinant proteins in plants is a valuable alternative to bioreactors using mammalian cell systems. Ease of scaling, and their inability to host human pathogens, enhance the use of plants to generate complex therapeutic products such as monoclonal antibodies. However, stably transformed plants expressing antibodies normally have a poor accumulation of these proteins that probably arise from the negative positional effects of their flanking chromatin. The induction of boundaries between the transgenes and the surrounding DNA using matrix attachment regions (MAR) and insulator elements may minimize these effects. With the PHB-01 antibody as a model, we demonstrated that the insertion of DNA elements, the TM2 (MAR) and M4 insulator, flanking the transcriptional cassettes that encode the light and heavy chains of the PHB-01 antibody, increased the protein accumulation that remained stable in the first plant progeny. The M4 insulator had a stronger effect than the TM2, with over a twofold increase compared to the standard construction. This effect was probably associated with an enhancer-promoter interference. Moreover, transgenic plants harboring two transcriptional units encoding for the PHB-01 heavy chain combined with both TM2 and M4 elements enhanced the accumulation of the antibody. In summary, the M4 combined with a double transcriptional unit of the heavy chain may be a suitable strategy for potentiating PHB-01 production in tobacco plants.

Field Trial and Molecular Characterization of RNAi-Transgenic Tomato Plants That Exhibit Resistance to Tomato Yellow Leaf Curl Geminivirus.

RNA interference (RNAi) is a widely used approach to generate virus-resistant transgenic crops. However, issues of agricultural importance like the long-term durability of RNAi-mediated resistance under field conditions and the potential side effects provoked in the plant by the stable RNAi expression remain poorly investigated. Here, we performed field trials and molecular characterization studies of two homozygous transgenic tomato lines, with different selection markers, expressing an intron-hairpin RNA cognate to the Tomato yellow leaf curl virus (TYLCV) C1 gene. The tested F6 and F4 progenies of the respective kanamycin- and basta-resistant plants exhibited unchanged field resistance to TYLCV and stably expressed the transgene-derived short interfering RNA (siRNAs) to represent 6 to 8% of the total plant small RNAs. This value outnumbered the average percentage of viral siRNAs in the nontransformed plants exposed to TYLCV-infested whiteflies. As a result of the RNAi transgene expression, a common set of up- and downregulated genes was revealed in the transcriptome profile of the plants selected from either of the two transgenic events. A previously unidentified geminivirus causing no symptoms of viral disease was detected in some of the transgenic plants. The novel virus acquired V1 and V2 genes from TYLCV and C1, C2, C3, and C4 genes from a distantly related geminivirus and, thereby, it could evade the repressive sequence-specific action of transgene-derived siRNAs. Our findings shed light on the mechanisms of siRNA-directed antiviral silencing in transgenic plants and highlight the applicability limitations of this technology as it may alter the transcriptional pattern of nontarget genes.

Lack of a relation between serum 25-hydroxyvitamin D concentrations and asthma in adolescents.

BACKGROUND: Decreased 25-hydroxyvitamin D [25(OH)D] concentrations have been associated with an increased prevalence and severity of asthma and a lower response to inhaled corticosteroids. OBJECTIVE: The objective was to determine the association between serum 25(OH)D concentrations and asthma prevalence, severity, and response to asthma treatment. DESIGN: Secondary analyses were conducted in 2 samples of adolescents 12-20 y of age: 1) NHANES 2001-2006 (n = 6487), a cross-sectional nationally representative sample of the US population, and 2) a cohort of inner-city adolescents with asthma managed prospectively for 46 wk with guidelines-based therapy in the Asthma Control Evaluation (ACE; n = 226) trial. RESULTS: Mean (±SD) serum 25(OH)D concentrations in the NHANES and ACE samples were lower in African Americans than in non-African Americans (NHANES: 14.9 ± 6.5 compared with 23.0 ± 8.4 ng/mL, P < 0.0001; ACE: 11.2 ± 6.9 compared with 15.8 ± 7.1 ng/mL, P < 0.0001). In the NHANES sample, mean concentrations did not differ between participants without and with asthma (African Americans: 14.9 ± 6.4 compared with 15.0 ± 6.6 ng/mL, respectively, P = 0.87; non-African Americans: 23.0 ± 8.5 compared with 23.6 ± 8.2 ng/mL, respectively, P = 0.16). In the ACE models that used either a predefined cutoff (<20 ng/mL) or linear regression, 25(OH)D concentrations showed either no relation or minor contradictory correlations with indicators of asthma severity, treatment requirements, spirometry, or atopy/inflammation. CONCLUSION: In 2 samples of adolescents, overall serum 25(OH)D concentrations were low and were not consistently associated with the presence of asthma, multiple asthma characteristics, asthma morbidity, or response to treatment. The ACE trial was registered at clinicaltrials.gov as NCT0011441.

Assessment of laryngopharyngeal sensation in children with dysphagia.

OBJECTIVES/HYPOTHESIS: To assess laryngopharyngeal sensation, prevalence of laryngopharyngeal sensory deficit and abnormal swallowing function parameters in children with dysphagia. STUDY DESIGN: Retrospective chart review. METHODS: The medical records of children who underwent flexible endoscopic evaluation of swallowing with sensory testing (FEESST) were reviewed. Laryngopharyngeal sensory threshold (LPST) was assessed based on the threshold intensity of air pulse stimulation eliciting laryngeal adductor reflex. Swallowing function parameters including pharyngeal residue, hypopharyngeal pooling of secretions, premature spillage, laryngeal penetration, and aspiration were evaluated. Prevalence of abnormal swallowing function parameters in children with normal and impaired LPST was compared. RESULTS: Forty children with dysphagia (28 male, 12 female; age range, 3 months to 17 years) underwent FEESST. LPST was normal in six patients, moderately impaired in 20 patients, and severely impaired in 10 patients. LPST could not be measured in four patients. Children showed one or more abnormal swallowing function parameters. The prevalence of abnormal swallowing parameters in patients with normal LPST was lower than that of patients with moderately or severely impaired LPST (P < .05). The prevalence of pharyngeal residue, hypopharyngeal pooling of secretions, and spillage in patients with severely impaired LPST was higher than that of patients with moderately impaired LPST (P < .05). CONCLUSIONS: The majority of children with dysphagia have impaired LPST. The prevalence of abnormal swallowing function parameters in children with normal LPST is lower than that in children with moderately or severely impaired LPST. Prevalence of aspiration tends to increase when the abnormal swallowing function parameters are associated with severely impaired LPST.

Development and validation of the Composite Asthma Severity Index--an outcome measure for use in children and adolescents.

BACKGROUND: Asthma severity is reflected in many aspects of the disease, including impairment and future risks, particularly for exacerbations. According to the Expert Panel Report 3: Guidelines for the Diagnosis and Management of Asthma, however, to assess more comprehensively the severity of asthma the level of current treatment needed to maintain a level of control should be included. OBJECTIVE: Development and validation of a new instrument, the Composite Asthma Severity Index (CASI), which can quantify disease severity by taking into account impairment, risk, and the amount of medication needed to maintain control. At present, there is no instrument available to measure and assess the multidimensional nature of asthma. METHODS: Twenty-six established asthma investigators, who are part of the National Institutes of Health-supported Inner City Asthma Consortium, participated in a modified Delphi consensus process to identify and weight the dimensions of asthma. Factor analysis was performed to identify independent domains of asthma by using the Asthma Control Evaluation trial. CASI was validated by using the Inner City Anti-IgE Therapy for Asthma trial. RESULTS: CASI scores include 5 domains: day symptoms and albuterol use, night symptoms and albuterol use, controller treatment, lung function measures, and exacerbations. At Asthma Control Evaluation trial enrollment, CASI ranged from 0 to 17, with a mean of 6.2. CASI was stable, with minimal change in variance after 1 year of treatment. In external validation, CASI detected a 32% larger improvement than did symptoms alone. CONCLUSION: CASI retained its discriminatory ability even with low levels of symptoms reported after months of guidelines-directed care. Thus, CASI has the ability to determine the level of asthma severity and provide a composite clinical characterization of asthma.

Life events and depressive symptoms in African American adolescents: do ecological domains and timing of life events matter?

Considerable research has documented associations between adverse life events and internalizing symptoms in adolescents, but much of this research has focused on the number of events experienced, with less attention to the ecological context or timing of events. This study examined life events in three ecological domains relevant to adolescents (i.e., family, peers, themselves) as predictors of the course of depressive symptoms among a community epidemiologically defined sample of 419 (47.2% females) urban African American adolescents. Given that youth depressive symptoms change over time, grade level was examined as a moderator. For males, the strength of associations between life events happening to participants, family life events, and peer life events and depressive symptoms did not change from grades 6-9. For females, the strength of the association between peer life events and depressive symptoms did not change over time, but the strength of associations between life events happening to participants and family life events and females' depressive symptoms decreased over time. Implications of the findings and directions for future research are discussed.

Adverse life events and depressive symptoms in african american youth: the role of control-related beliefs.

The association between experiences of adverse life events and adolescent depressive symptoms has been well documented. However, this association is not consistently observed in urban and low income African American youth. In addition, mechanisms linking life event stress and African American adolescents' depressive symptoms have received little attention. This study examined past year violent and nonviolent life events assessed in 6th grade as predictors of 7th grade depressive symptoms among a community epidemiologically defined sample of 447 (47% girls) urban African American adolescents. Depressive symptoms were assessed twice, at a 1-year interval, and initial depressive symptoms were controlled in the analyses. Control-related beliefs were examined as mediators of the association between life events and depressive symptoms, and gender was examined as a moderator of the association between control-related beliefs and depressive symptoms. Associations among study variables were examined in a series of models, from general to more specific. A model in which nonviolent and violent life events were examined separately and control and contingency beliefs examined as one latent variable was the most informative about the etiology of depressive symptoms in a sample of urban, African American youth. Implications of the findings for preventive interventions and future research are discussed.

Influence of the landscape matrix on the abundance of arboreal primates in fragmented landscapes.

Composition of the landscape matrix of surrounding forest fragments is thought to be critically important to the survival of arboreal primates because it offers structures that help the animals move between fragments and other foraging sites. However, little is known about the composition of the matrix used by these animals. The aim of this study was to quantitatively assess the importance of the landscape matrix and its effects on primate abundance, using black howler monkeys (Alouatta pigra) living in a landscape fragmented by the expansion of agriculture and pastures for livestock in southeastern Mexico. In 2008, a complete census of the monkeys was carried out across the 2000-ha landscape matrix, and for every site where we observed monkeys, we recorded canopy height, tree basal area, food-source abundance, and distance to the nearest fragment. A total of 244 howler monkeys, distributed among 48 groups (including six solitary males) were counted in the matrix. Mean troop size was 5.6 ± 2.8 individuals, and the mode was three individuals. The highest number of troops and greatest howler monkey abundance were recorded in the isolated trees, the eucalyptus plantation, and orchards. A generalized linear model revealed that monkey abundance tended to be higher in matrix elements with higher canopy height, greater food availability, and closest to rainforest fragments. These results suggest that it is necessary to take into account the many elements of the landscape when drawing up conservation and habitat management plans, particularly in order to establish connectivity among the fragments and elements of the matrix with native trees.

Current status of the habitat and population of the black howler monkey (Alouatta pigra) in Balancán, Tabasco, Mexico.

We evaluated the habitat and populations of the black howler monkey (Alouatta pigra) in the municipality of Balancán, Tabasco, southeastern Mexico, using a combination of field surveys and remotely sensed data. We identified 21,937 ha of remnant vegetation composed of 1,348 fragments. Fragments separated by up to 200 m were grouped into "clusters" of fragments in accordance with the maximum observed open distance crossed by A. pigra. A total of 11% or 84 of the 772 clusters identified through remote sensing were selected at random, and for these we determined the vegetation type, canopy height, area, and distance to the closest human settlement. In these same 84 clusters, which included a total area of 9,817 ha, from October to June of 2006 we located a total of 1,064 black howler monkeys, including 228 troops and 49 solitary monkeys. A. pigra was found in 62 (74.7%) of all clusters visited, with a cumulative area of 6,032 ha. Troops varied in size from 2 to 15 individuals (average 6.0+/-2.9 ind/troop). Adults were 67% (n=716) of detected individuals, whereas juveniles were 20.5% (n=218) and infants were 12.5% (n=133). We found black howlers to occur at an ecological density of 10.8 ind/km(2), which is low in comparison with A. pigra in other fragmented and conserved sites. We found a statistically significant relationship between the area of clusters and the abundance of howler monkeys (r(2)=0.2, F=10.47, gl=3, P=0.002). In addition, the probability of finding A. pigra was greater in secondary vegetation, riparian vegetation, tropical dry forest, undisturbed tropical oak forest, and palm forest (F=12, gl=3, P<0.0001), as compared with disturbed tropical oak forest. Our results provide data on the distribution, abundance, and population structure of black howler monkeys in a fragmented landscape in the southeast of Mexico. These data are a necessary prerequisite for conservation planning for this species.

A transformation procedure for recalcitrant tomato by addressing transgenic plant-recovery limiting factors.

Agrobacterium tumefaciens technology is the battle horse for tomato genetic transformation. However, tomato varieties with low regeneration capacity are very difficult to transform. In the past, tomato transformation through Agrobacterium infection was focused on varieties capable of high regeneration yield, while successful transformation of low regenerable cultivars has not been reported. The genotype response to tissue culture conditions is believed to drive the frequency of regeneration of transgenic plant, whereas the capacity for cell proliferation could determine the transformation efficiency through this technology. The Campbell-28 cultivar is an example of constraints arising from a high morphogenetic potential with low conversion compared to normal plants. In the present work the roles that contribute to improved transgenic plant recovery from this recalcitrant variety were explored for factors like Agrobacterium concentration and antibiotics for bacterial removal and transformant selection. Analysis of the efficiency from independent transformation experiments revealed a more than twofold increase of transformant regeneration after selection on ammonium glufosinate compared to kanamycin selection, showing a transformation efficiency of 21.5%.

Allergic airway responses in obese mice.

RATIONALE: Epidemiologic data indicate an increased incidence of asthma in the obese. OBJECTIVES: To determine whether obese mice exhibit augmented pulmonary responses after allergen sensitization and challenge. METHODS: Lean, wild-type (C57BL/6), obese ob/ob, and obese db/db mice were sensitized to ovalbumin (OVA), and then challenged with aerosolized OVA or phosphate-buffered saline (PBS). Changes in total pulmonary resistance (Rl) induced by intravenous methacholine were measured by forced oscillation. Blood was collected, bronchoalveolar lavage (BAL) was performed, and lungs were harvested for measurement of cytokine expression by real-time reverse transcription-polymerase chain reaction. MEASUREMENTS AND MAIN RESULTS: OVA challenge increased baseline Rl in ob/ob, but not wild-type, mice, and airway responsiveness was greater in ob/ob than wild-type mice, regardless of the challenge. Compared with PBS, OVA challenge caused an increase in the number of BAL fluid (BALF) cells, an increase in lung Th2 cytokine expression, and an increase in serum IgE. Significantly fewer BALF cells were recovered from OVA-challenged ob/ob versus wild-type mice, whereas serum IgE levels were elevated significantly more in ob/ob versus wild-type mice. BALF and lung Th2 cytokine expression was not different in ob/ob versus wild-type mice. Airway responsiveness was greater in db/db versus wild-type mice, regardless of the challenge, and OVA caused airway hyperresponsiveness in db/db but not wild-type mice, despite reduced BALF cells in OVA-challenged db/db versus wild-type mice. CONCLUSIONS: These results demonstrate that obesity enhances OVA-induced changes in pulmonary resistance and serum IgE and that these changes are not the result of increased Th2 type airway inflammation.

Churg-Strauss syndrome in children: a clinical and pathologic review.

Churg-Strauss syndrome is a vasculitis accompanied by asthma and eosinophilia. It is generally considered a disease of adults; occurrence in children has been reported infrequently. Here we report 2 pediatric patients with Churg-Strauss syndrome manifesting with prominent pulmonary involvement. One, a 16-year-old with a previous history of asthma, presented with pleuritic chest pain and a peripheral pulmonary nodule complicated by an eosinophilic pleural effusion. The other patient presented at age 6 with cough, weight loss, and radiographic infiltrates. Lung biopsies revealed elements characteristic of Churg-Strauss syndrome, including eosinophilic microabscesses and vasculitis. Three- and 5-year follow-up showed continued symptoms in both patients despite medical therapy. Both patients illustrate many of the typical features of Churg-Strauss syndrome. We report these cases to expand the scant knowledge about Churg-Strauss syndrome in pediatric patients and to heighten awareness that this serious disease may affect the pediatric population. The relevant literature on Churg-Strauss syndrome, with specific reference to childhood cases, is reviewed.

Intron-hairpin RNA derived from replication associated protein C1 gene confers immunity to tomato yellow leaf curl virus infection in transgenic tomato plants.

The whitefly-transmitted Tomato Yellow Leaf Curl Virus (TYLCV) is the major pathogen of tomato crop in Cuba and one of the most outstanding viral diseases of plants worldwide. In this work, we have developed transgenic tomato plants, transformed with an intron-hairpin genetic construction to induce post- transcriptional gene silencing against the early TYLCV replication associated protein gene (C1). The intron-hairpin RNA produced involves 726 nts of the 3' end of the TYLCV C1 gene as the arms of the hairpin, and the castor bean catalase intron. Transgenic tomato plants belonging to line 126, which harbor a single transgene copy, showed immunity to TYLCV, even in extreme conditions of infection (4-leaf-stage plants and 300 to many hundreds viruliferous whiteflies per plant during 60 days). Dot blot hybridization of these plants showed no TYLCV DNA presence 60 days after inoculation. Small interfering RNA molecules were detected in both inoculated and non-inoculated plants from line 126. These transgenic tomato plants of the otherwise very TYLCV-susceptible Campbell-28 tomato cultivar, are the first report of resistance to a plant DNA virus obtained by the use of the intron-hairpin RNA approach.

Beneficial effect of retinoic acid on the outcome of experimental acute renal failure.

BACKGROUND: Retinoic acid (RA) exerts beneficial effects on vascular remodelling and experimental nephritis, and plays a role in kidney development. Pathological changes caused by acute renal failure (ARF) result in high mortality. We determined whether RA ameliorates ARF-induced pathology caused by potassium dichromate (PD). METHODS: Adult Wistar female rats (210-250 g) were randomly allocated to four groups: (i) an ARF group that received PD [15 mg/kg body weight (bw), single dose subcutaneously]; (ii) a group that received PD plus RA (1 mg/kg bw) beginning at 5 days before PD and that continued for 14 additional days; (iii) a group that received PD plus thyroxine (T(4); 8 micro g/100 g bw) with RA; and (iv) a group that received only the vehicle for PD (saline solution). We evaluated functional, biochemical and morphological characteristics of the kidneys. RESULTS: PD-induced alterations in serum creatinine, creatinine clearance (C(cr)) and fractional excretion of sodium (FeNa) were less severe when rats received RA. PD increased lipoperoxidation and this alteration was partially blocked by RA. Animals undergoing ARF showed severe histological injury (brush border loss, acidophilia, oedema, pyknosis, karyorhexis, cell detachment and disruption of the basement membrane). These alterations were less severe in RA-treated rats, indicating a protective effect on functional and morphological alterations. Alterations in urinary sediment were reduced by RA. The simultaneous administration of T(4) with RA did not produce additional protection. CONCLUSION: RA exerted beneficial effects on the duration and severity of renal damage induced by PD in a model of renal failure resembling ARF in humans. The protective effect of RA may be mediated by diminished lipoperoxidative damage.