Does vaginal surgery for correction of pelvic organ prolapse improve urinary function? A prospective cohort study.

INTRODUCTION AND HYPOTHESIS: Pelvic organ prolapse (POP) is caused by an imbalance in the stability of the pelvic organs, resulting in loss of support. The most common types of POP, anterior and apical, are associated with lower urinary tract symptoms (LUTS) such as bladder outlet obstruction and detrusor overactivity (DO). Vaginal surgery may improve LUTS and overall urinary symptoms. We assessed urodynamic (UD) parameters and urinary symptoms before and after vaginal surgery for POP correction. METHODS: A prospective cohort of 59 women with symptomatic anterior and/or apical POP associated with urinary symptoms and with indications for vaginal surgery were included. POP surgeries included anterior colporrhaphy and vaginal hysterectomy with culdoplasty (VH) and with/without concomitant posterior colporrhaphy and mid-urethral sling (MUS). All participants underwent UD evaluation and answered urinary symptom questionnaires pre- and 3 months post-surgery. RESULTS: Anterior colporrhaphy was performed in all patients: 45.7% with associated VH and 54.2% with concomitant MUS. Preoperative ICIQ-OAB score >8 points was significantly associated with DO (p<0.02) and decreased after surgery (9±4.3 to 3.2±3.0, p<0.001). All other questionnaires demonstrated improvements in urinary symptoms. Stress urinary incontinence rate decreased from 59.6% to 21% (p<0.001). Post-void residual (PVR) volume and Valsalva maneuver also decreased (p<0.001). CONCLUSIONS: Pelvic organ prolapse surgery reduced the prevalence of urgency symptoms, and all questionnaires on urinary symptoms showed clinically significant improvement. Vaginal surgery for POP, even combined with MUS, significantly reduced PVR volume and improved urgency symptoms.

Hydroclimate changes across the Amazon lowlands over the past 45,000 years.

Reconstructing the history of tropical hydroclimates has been difficult, particularly for the Amazon basin-one of Earth's major centres of deep atmospheric convection. For example, whether the Amazon basin was substantially drier or remained wet during glacial times has been controversial, largely because most study sites have been located on the periphery of the basin, and because interpretations can be complicated by sediment preservation, uncertainties in chronology, and topographical setting. Here we show that rainfall in the basin responds closely to changes in glacial boundary conditions in terms of temperature and atmospheric concentrations of carbon dioxide. Our results are based on a decadally resolved, uranium/thorium-dated, oxygen isotopic record for much of the past 45,000 years, obtained using speleothems from Paraíso Cave in eastern Amazonia; we interpret the record as being broadly related to precipitation. Relative to modern levels, precipitation in the region was about 58% during the Last Glacial Maximum (around 21,000 years ago) and 142% during the mid-Holocene epoch (about 6,000 years ago). We find that, as compared with cave records from the western edge of the lowlands, the Amazon was widely drier during the last glacial period, with much less recycling of water and probably reduced plant transpiration, although the rainforest persisted throughout this time.

Convalescent plasma for COVID-19 in hospitalised patients: an open-label, randomised clinical trial.

BACKGROUND: The effects of convalescent plasma (CP) therapy in hospitalised patients with coronavirus disease 2019 (COVID-19) remain uncertain. This study investigates the effect of CP on clinical improvement in these patients. METHODS: This is an investigator-initiated, randomised, parallel arm, open-label, superiority clinical trial. Patients were randomly (1:1) assigned to two infusions of CP plus standard of care (SOC) or SOC alone. The primary outcome was the proportion of patients with clinical improvement 28 days after enrolment. RESULTS: A total of 160 (80 in each arm) patients (66.3% critically ill, 33.7% severely ill) completed the trial. The median (interquartile range (IQR)) age was 60.5 (48-68) years; 58.1% were male and the median (IQR) time from symptom onset to randomisation was 10 (8-12) days. Neutralising antibody titres >1:80 were present in 133 (83.1%) patients at baseline. The proportion of patients with clinical improvement on day 28 was 61.3% in the CP+SOC group and 65.0% in the SOC group (difference -3.7%, 95% CI -18.8-11.3%). The results were similar in the severe and critically ill subgroups. There was no significant difference between CP+SOC and SOC groups in pre-specified secondary outcomes, including 28-day mortality, days alive and free of respiratory support and duration of invasive ventilatory support. Inflammatory and other laboratory marker values on days 3, 7 and 14 were similar between groups. CONCLUSIONS: CP+SOC did not result in a higher proportion of clinical improvement on day 28 in hospitalised patients with COVID-19 compared to SOC alone.

Maintained barostatic regulation of heart rate in digesting snakes (Boa constrictor).

When snakes digest large meals, heart rate is accelerated by withdrawal of vagal tone and an increased non-adrenergic-non-cholinergic tone that seems to stem from circulating blood-borne factors exerting positive chronotropic effects. To investigate whether this tonic elevation of heart rate impairs the ability for autonomic regulation of heart during digestion, we characterised heart rate responses to pharmacological manipulation of blood pressure in the snake Boa constrictor through serial injections of sodium nitroprusside and phenylephrine. Both fasting and digesting snakes responded with a robust tachycardia to hypotension induced by sodium nitroprusside, with digesting snakes attaining higher maximal heart rates than fasting snakes. Both fasting and digesting snakes exhibited small reductions of the cardiac chronotropic response to hypertension, induced by injection of phenylephrine. All heart rate changes were abolished by autonomic blockade with the combination of atropine and propranolol. The digesting snakes retained the capacity for compensatory heart rate responses to hypotension, despite their higher resting values, and the upward shift of the barostatic response curve enables snakes to maintain the cardiac limb of barostatic regulation for blood pressure regulation.

South American monsoon response to iceberg discharge in the North Atlantic.

Heinrich Stadials significantly affected tropical precipitation through changes in the interhemispheric temperature gradient as a result of abrupt cooling in the North Atlantic. Here, we focus on changes in South American monsoon precipitation during Heinrich Stadials using a suite of speleothem records covering the last 85 ky B.P. from eastern South America. We document the response of South American monsoon precipitation to episodes of extensive iceberg discharge, which is distinct from the response to the cooling episodes that precede the main phase of ice-rafted detritus deposition. Our results demonstrate that iceberg discharge in the western subtropical North Atlantic led to an abrupt increase in monsoon precipitation over eastern South America. Our findings of an enhanced Southern Hemisphere monsoon, coeval with the iceberg discharge into the North Atlantic, are consistent with the observed abrupt increase in atmospheric methane concentrations during Heinrich Stadials.

Pharmacodynamics of propofol and alfaxalone in rattlesnakes (Crotalus durissus).

To characterise the effect of two common induction agents, propofol and alfaxalone, on mean arterial blood pressure (MAP) and heart rate (HR), we equipped 19 adult South American rattlesnakes (Crotalus durissus) with an indwelling arterial catheter approximately 24 h prior to recording of baseline resting values. Then, seven snakes received alfaxalone (15 mg kg-1) intravascularly (IV) through the catheter, while groups two and three (both n = 6) received propofol (15 mg kg-1 IV). The first two groups were not handled, while the group 3 was manually restrained for 2 min for a mock injection of 0.2 ml saline into the ventral tail vein. Baseline HR was similar in all groups and handling caused a significant tachycardia (p = 0.031) in group three. When given IV to undisturbed animals, both propofol and alfaxalone induced a significant increase in HR (p = 0.0022 and p = 0.0045, respectively) lasting approximately 30 min, but with values only significantly exceeding baseline for the first 5 min for propofol and the first 10 min with alfaxalone. Handling caused a significant increase in MAP (p = 0.0313). Propofol did not affect MAP (p = 0.1064), while alfaxalone caused a marked hypertension (although only significant at 2 min; p = 0.031). Manual restraint significantly increases both HR and MAP, which may lead to a masking of true cardiovascular effects of anaesthetic agents.

Fitness and mating compatibility of Chrysodeixis includens (W.) (Lepidoptera: Noctuidae) populations collected in different provinces and crops in Argentina.

Chrysodeixis includens, is an important Plusiinae pest that feeds on soybean, beans, and cotton. This species has a genetic structure determined by molecular markers in populations collected in soybean crops in Brazil and has developed resistance to insecticides. This had led to an increased interest in the genetic diversity of its populations in Argentina. This study aimed to characterize the fitness parameters and mating compatibility of geographically distant C. includens populations and on different host plants in Argentina. Intra- and inter-population crosses revealed that C. includens populations from Tucumán and Santiago del Estero provinces did not present any evidence of prezygotic and postzygotic incompatibilities, suggesting that both populations collected from soybean plants belonged to a single wide-ranging species. Prezygotic and postzygotic incompatibilities were detected between populations collected from different crops (soybean and bean). These incompatibilities may be caused by the different nutrients that each plant species renders, or the specific pest control strategies which may affect C. includens behavior. Studies of the genetic structure of C. includens populations based on mating isolation on other crops, as well as of the impact of management strategies on the specie, will increase understanding of the reproductive compatibility revealed by the present study.

Intraspecific variation in the axial skeleton of Aetosauroides scagliai (Archosauria: Aetosauria) and its implications for the aetosaur diversity of the Late Triassic of Brazil.

Aetosauria represents a remarkable clade of armored pseudosuchians in which some of its oldest members are recovered from late Carnian units of Brazil. Three species are known: the mid-sized aetosaur Aetosauroides scagliai, which also occurs in Argentina, and two small-sized species, Aetobarbakinoides brasiliensis and Polesinesuchus aurelioi. We provide a detailed description and comparative analysis of the axial skeleton of Aetosauroides, identifying some diagnostic features as variable. These include the deep pocket pit lateral to the base of the neural spine, the presence of the infradiapophyseal laminae and the lateral fossa ventral to the neurocentral suture. These features are not found in smaller and immature Aetosauroides specimens, resembling the condition found in Polesinesuchus, which is based solely on a juvenile individual, as revealed by osteoderm microstructure analysis. As Polesinesuchus cannot be anatomically differentiated from other small individuals of Aetosauroides, we propose it as a junior synonym of Aetosauroides scagliai. Our results shrink the number of putative 'dwarf' aetosaurs, indicating that morphological variation related to ontogeny affects aetosaur taxonomy and phylogeny.

Detection and Classification System for Rail Surface Defects Based on Eddy Current.

The prospect of growth of a railway system impacts both the network size and its occupation. Due to the overloaded infrastructure, it is necessary to increase reliability by adopting fast maintenance services to reach economic and security conditions. In this context, one major problem is the excessive friction caused by the wheels. This contingency may cause ruptures with severe consequences. While eddy's current approaches are adequate to detect superficial damages in metal structures, there are still open challenges concerning automatic identification of rail defects. Herein, we propose an embedded system for online detection and location of rails defects based on eddy current. Moreover, we propose a new method to interpret eddy current signals by analyzing their wavelet transforms through a convolutional neural network. With this approach, the embedded system locates and classifies different types of anomalies, enabling an optimization of the railway maintenance plan. Field tests were performed, in which the rail anomalies were grouped in three classes: squids, weld and joints. The results showed a classification efficiency of ~98%, surpassing the most commonly used methods found in the literature.

Detection of porcine circovirus type 2 (PCV2) in the Philippines and the complexity of PCV2-associated disease diagnosis.

Porcine circovirus type 2 (PCV2), an important pig viral pathogen, can cause porcine circovirus-associated disease (PCVAD), resulting in economic losses associated with decreased growth and mortalities. The diagnosis of PCVAD is complex requiring clinical, pathological and virological approaches. This study assessed PCV2 infection using histopathology and immunohistochemistry (IHC) on tissue samples and quantitative polymerase chain reaction (qPCR) on serum samples from 47 grower-finisher pigs allocated in three clinical groups in the Philippines. Typical PCV2 histopathological lesions were observed in mediastinal lymph nodes (MLN) of eight of 47 pigs. Lymphoid depletion was seen in all eight pigs and granulomatous inflammation in one of these pigs. Four of these eight pigs were PCV2 positive by both IHC and qPCR. IHC revealed PCV2 antigen in 8 pigs in at least one of the following tissues: MLN (5/8), spleen (3/8), tonsils (4/8) and lungs (5/8). PCV2 antigen was observed in 3/8 MLN with lymphoid depletion and in one MLN with depletion and granulomatous inflammation. The qPCR test showed that 33 sera had a non-detectable level, twelve had < 106 and two had > 106 PCV2 DNA copies/ml serum. One pig with lymphoid depletion had > 106 PCV2 DNA copies/ml serum, and another pig without MLN lesions also had > 106 PCV2 DNA copies/ml serum. These findings suggest that PCVAD is present in the Philippines and confirm the challenges of PCVAD diagnosis as different patterns of results were obtained from the different tests.

Cholinergic regulation along the pulmonary arterial tree of the South American rattlesnake: vascular reactivity, muscarinic receptors, and vagal innervation.

Vascular tone in the reptilian pulmonary vasculature is primarily under cholinergic, muscarinic control exerted via the vagus nerve. This control has been ascribed to a sphincter located at the arterial outflow, but we speculated whether the vascular control in the pulmonary artery is more widespread, such that responses to acetylcholine and electrical stimulation, as well as the expression of muscarinic receptors, are prevalent along its length. Working on the South American rattlesnake (Crotalus durissus), we studied four different portions of the pulmonary artery (truncus, proximal, distal, and branches). Acetylcholine elicited robust vasoconstriction in the proximal, distal, and branch portions, but the truncus vasodilated. Electrical field stimulation (EFS) caused contractions in all segments, an effect partially blocked by atropine. We identified all five subtypes of muscarinic receptors (M1-M5). The expression of the M1 receptor was largest in the distal end and branches of the pulmonary artery, whereas expression of the muscarinic M3 receptor was markedly larger in the truncus of the pulmonary artery. Application of the neural tracer 1,1'-dioctadecyl-3,3,3',3'-tetramethylindo-carbocyanine perchlorate (DiI) revealed widespread innervation along the whole pulmonary artery, and retrograde transport of the same tracer indicated two separate locations in the brainstem providing vagal innervation of the pulmonary artery, the medial dorsal motor nucleus of the vagus and a ventro-lateral location, possibly constituting a nucleus ambiguus. These results revealed parasympathetic innervation of a large portion of the pulmonary artery, which is responsible for regulation of vascular conductance in C. durissus, and implied its integration with cardiorespiratory control.

Heart rate variability in the tegu lizard, Salvator merianae, its neuroanatomical basis and role in the assessment of recovery from experimental manipulation.

Using long-term, remote recordings of heart rate (fH) on fully recovered, undisturbed lizards, we identified several components of heart rate variability (HRV) associated with respiratory sinus arrhythmia (RSA): 1.) A peak in the spectral representation of HRV at the frequency range of ventilation. 2.) These cardiorespiratory interactions were shown to be dependent on the parasympathetic arm of the autonomic nervous system. 3.) Vagal preganglionic neurons are located in discrete groups located in the dorsal motor nucleus of the vagus and also, in a ventro-lateral group, homologous to the nucleus ambiguus of mammals. 4.) Myelinated nerve fibers in the cardiac vagus enabling rapid communication between the central nervous system and the heart. Furthermore, the study of the progressive recovery of fH in tegu following anesthesia and instrumentation revealed that 'resting' levels of mean fH and reestablishment of HRV occurred over different time courses. Accordingly, we suggest that, when an experiment is designed to study a physiological variable reliant on autonomic modulation at its normal, resting level, then postsurgical reestablishment of HRV should be considered as the index of full recovery, rather than mean fH.

Swimming exercise changed the collagen synthesis and calcification in calcaneal tendons of mice.

Obesity is characterized by the excess of body fat and, therefore, may cause musculoskeletal alterations that can negatively influence the tendons. Such overweight-influenced alterations are exercise sensitive though. Morphological and biochemical alterations were reported in the calcaneal tendon of mice submitted to a lipid-rich diets along with practicing exercises, with the following groups: normal diet without exercise (ND), normal diet with exercise (NDex), lipid-rich diet without exercise (LD), lipid-rich diet without exercise (LDex). The calcaneal tendons were removed and subjected to histological and biochemical analysis. Layers of the tissue were stained with Hematoxylin and Eosin, Picrosirius Red and Von Kossa while a protein dosage was conduce by the Bradford method. The morphologicals analysis there was no statistical difference concerning the number of fibroblasts among the groups. Groups submitted to exercises showed higher amount of collagen and non-collagenous protein deposition. The lipid-rich diet without exercse group had a more disorganized collagen matrix with intense basophilia. The same group had areas of calcification confirmed by Von Kossa technique. Practicing physical activity, such as swimming, can improve the changes caused in the calcaneal tendon in mice submitted to a lipid-rich diets, having a better collagen organization and the synthesis.

Identification and Localization of Track Circuit False Occupancy Failures Based on Frequency Domain Reflectometry.

Railway track circuit failures can cause significant train delays and economic losses. A crucial point of the railway operation system is the corrective maintenance process. During this operation, the railway lines have the circulation of trains interrupted in the respective sector, where traffic restoration occurs only after completing the maintenance process. Depending on the cause and length of the track circuit, identifying and solving the problem may take a long time. A tool that assists in track circuit fault detection during an inspection adds agility and efficiency in its restoration and cost reduction. This paper presents a new method, based on frequency domain reflectometry, to diagnose and locate false occupancy failures of track circuits. Initially, simulations are performed considering simplified track circuit approximations to demonstrate the operation of the proposed method, where the fault position is estimated by identifying the null points and through non-linear regression on signal amplitude response. A field test is then carried out in a track circuit approximately 1500 m long to validate the proposed method. The results show that the proposed method can identify and estimate the fault location due to a short circuit between rails with high accuracy.

Renal Outcomes of Vasopressin and Its Analogs in Distributive Shock: A Systematic Review and Meta-Analysis of Randomized Trials.

OBJECTIVES: To systematically review the literature and synthesize evidence concerning the effects of vasopressin and its analogs compared with other vasopressors in distributive shock, focusing on renal outcomes. DATA SOURCES: We performed a systematic review in MEDLINE, Embase, Cochrane Central, and Clinicaltrials.gov databases. STUDY SELECTION: Randomized clinical trials that compared vasopressin and its analogs with other vasopressors and reported renal outcomes in adult patients with distributive shock. DATA EXTRACTION: Paired reviewers independently screened citations, conducted data extraction and assessed risk of bias. Three prespecified subgroup analyses were conducted. Three main outcomes related to acute renal failure were analyzed: the need for renal replacement therapy, acute kidney injury incidence, and acute kidney injury-free days. I test was used to evaluate heterogeneity between studies. Substantial heterogeneity was defined as I greater than 50%. A random-effects model with Mantel-Haenszel weighting was used for all analyses. Heterogeneity was explored using subgroup analysis. The quality of evidence for intervention effects was summarized using Grading of Recommendations Assessment, Development, and Evaluation methodology. This study was registered in the PROSPERO database (CRD42017054324). DATA SYNTHESIS: Three-thousand twenty-six potentially relevant studies were identified, and 30 articles were reviewed in full. Seventeen studies met the inclusion criteria, including a total of 2,833 individuals. Of these, 11 studies (2,691 individuals) were suitable for quantitative meta-analysis. Overall, the evidence was of low to moderate quality. Patients who received vasopressin and its analogs had a reduced need for renal replacement therapy (odds ratio, 0.59 [0.37-0.92]; p = 0.02; I = 49%) and a lower acute kidney injury incidence (odds ratio, 0.58 [0.37-0.92]; p = 0.02; I = 63%). These results should be interpreted with caution, due to excessive heterogeneity. Acute kidney injury-free data was not pooled, since the small number of studies and extreme heterogeneity. CONCLUSIONS: In patients with distributive shock, vasopressin and its analogs use is associated with a reduced need for renal replacement therapy and lower acute kidney injury incidence. These results are supported by high risk of bias evidence.

The respiratory mechanics of the yacare caiman (Caiman yacare).

The structure and function of crocodilian lungs are unique compared with those of other reptiles. We examined the extent to which this and the semi-aquatic lifestyle of crocodilians affect their respiratory mechanics. We measured changes in intratracheal pressure in adult and juvenile caiman (Caiman yacare) during static and dynamic lung volume changes. The respiratory mechanics of juvenile caiman were additionally measured while the animals were floating in water and submerged at 30, 60 and 90 deg to the water's surface. The static compliance of the juvenile pulmonary system (2.89±0.22 ml cmH2O-1 100 g-1) was greater than that of adults (1.2±0.41 ml cmH2O-1 100 g-1), suggesting that the system stiffens as the body wall becomes more muscular and keratinized in adults. For both age groups, the lungs were much more compliant than the body wall, offering little resistance to air flow (15.35 and 4.25 ml cmH2O-1 100 g-1 for lungs, versus 3.39 and 1.67 ml cmH2O-1 100 g-1 for body wall, in juveniles and adults, respectively). Whole-system dynamic mechanics decreased with increasing ventilation frequency (fR), but was unaffected by changes in tidal volume (VT). The vast majority of the work of breathing was required to overcome elastic forces; however, work to overcome resistive forces increased proportionally with fR Work of breathing was higher in juvenile caiman submerged in water at 90 deg because of an increase in work to overcome both elastic and flow resistive forces. The lowest power of breathing was found to occur at high fR and low VT for any given minute ventilation (V̇E) in caiman of all ages.

TcNST2 encodes a Golgi-localized UDP-galactose transporter in Trypanosoma cruzi.

Survival and infectivity of trypanosomatids rely on cell-surface and secreted glycoconjugates, many of which contain a variable number of galactose residues. Incorporation of galactose to proteins and lipids occurs along the secretory pathway from UDP-galactose (UDP-Gal). Before being used in glycosylation reactions, however, this activated sugar donor must first be transported across the endoplasmic reticulum and Golgi membranes by a specific nucleotide sugar transporter (NST). In this study, we identified an UDP-Gal transporter (named TcNST2 and encoded by the TcCLB.504085.60 gene) from Trypanosoma cruzi, the etiological agent of Chagas disease. TcNST2 was identified by heterologous expression of selected putative nucleotide sugar transporters in a mutant Chinese Hamster Ovary cell line. TcNST2 mRNA levels were detected in all T. cruzi life-cycle forms, with an increase in expression in axenic amastigotes. Confocal microscope analysis indicated that the transporter is specifically localized to the Golgi apparatus. A three-dimensional model of TcNST2 suggested an overall structural conservation as compared with members of the metabolite transporter superfamily and also suggested specific features that could be related to its activity. The identification of this transporter is an important step toward a better understanding of glycoconjugate biosynthesis and the role NSTs play in this process in trypanosomatids.

Blood flow distribution in embryonic common snapping turtles Chelydra serpentina (Reptilia; Chelonia) during acute hypoxia and α-adrenergic regulation.

Embryonic turtles have four distinct vascular beds that separately perfuse the developing embryo's body and the extra-embryonic yolk sac, amnion and chorioallantoic membrane (CAM). The mechanisms enabling differential regulation of blood flow through these separate beds, in order to meet the varying demands of the embryo during development, is of current interest. The present investigation followed the changes in blood flow distribution during an acute exposure to hypoxia and after α-adrenergic blockade. We monitored heart rate (fH), mean arterial pressure (Pm), and determined relative blood flow distribution (%Q̇sys) using colored microspheres. At 70% and 90% of the incubation period hypoxia elicited a bradycardia without changing Pm while %Q̇sys was altered only at 70%, increasing to the CAM and liver. Blockade of α-adrenergic responses with phentolamine did not change fH or Pm but increased %Q̇sys to the shell. These results show the capacity of embryos to redistribute cardiac output during acute hypoxia, however α-adrenergic receptors seemed to play a relatively small role in embryonic cardiovascular regulation.

Mammal tooth traces in a ferruginous cave in southeastern Brazil and their relevance to cave legal protection.

We describe the first occurrence of biogenic traces made by mammals within an iron formation cave located in the Serra da Ferrugem Ridge, in Southeastern Brazil. These bioerosions are tooth traces produced in boulders, walls and floor within the cave. The traces occur as sets of two or more grooves, which are highly variable in size. The grooves were compared to tooth traces artificially produced by imprinting the incisors of different mammal species collected in the cave region on soft clay. Among those, the following taxa are potential tracemakers: Akodon sp., Oligoryzomys sp., Necromys lasiurus, Rhipidomys mastacalis, Oecomys gr. concolor, Trinomys moojeni, and Hydrochoerus hydrochaeris. The age of the traces is unknown; therefore, any discussion on its fossil nature is circumstantial. Regardless of its relevance to paleontology, the presence of ichnological features should be considered as an additional cave value, according to the current Brazilian legislation regarding cave protection.

Performance of Field-Collected Spodoptera frugiperda (Lepidoptera: Noctuidae) Strains Exposed to Different Transgenic and Refuge Maize Hybrids in Argentina.

Spodoptera frugiperda (J. E. Smith) is one of the major pests of maize in Argentina. The main tool for its control is the use of genetically modified maize hybrids expressing Bacillus thuringiensis (Bt) insecticidal proteins. Maize growers in Argentina initially controlled this pest with Bt maize that expressed a single Bt protein (Cry1Ab or Cry1F). Currently it is necessary to plant maize cultivars that produce two Bt proteins to achieve the satisfactory control. Recently, Cry1F field-evolved resistant populations of this species were confirmed in Argentina. The objective of this study was to evaluate the performance of S. frugiperda field-collected strains on different Bt and non-Bt maize hybrids. Strains were collected from non-Bt maize (T1), Agrisure TDMax (T2), Agrisure Viptera (T3), Agrisure Viptera 3110 (T4), Genuity VT Triple Pro (T5), and Power Core (T6). Three experiments were performed to 1) determine the survivorship and reproduction of field-collected larvae (F0) from Bt maize hybrids, 2) evaluate Cry1F resistance using an F1 screen, and 3) assess the performance of F1 strains on different maize hybrids. In the F0, the survivorship from larva to adult ranged from 0 to 63%. We obtained adults from only the T1, T2, T5, and T6 strains with no significant differences in the reproductive parameters. Continuously rearing F1 larvae on their collected hosts affected larval duration, which was significantly shorter for a known-laboratory Bt-susceptible strain than the field-collected strains. Our results support the existence of Cry1F-resistance alleles in S. frugiperda field populations in Argentina.