Phytosulfokine promotes fruit ripening and quality via phosphorylation of transcription factor DREB2F in tomato.

Phytosulfokine (PSK), a plant peptide hormone with a wide range of biological functions, is recognized by its receptor PHYTOSULFOKINE RECEPTOR 1 (PSKR1). Previous studies have reported that PSK plays important roles in plant growth, development, and stress responses. However, the involvement of PSK in fruit development and quality formation remains largely unknown. Here, using tomato (Solanum lycopersicum) as a research model, we show that exogenous application of PSK promotes the initiation of fruit ripening and quality formation, while these processes are delayed in pskr1 mutant fruits. Transcriptomic profiling revealed that molecular events and metabolic pathways associated with fruit ripening and quality formation are affected in pskr1 mutant lines and transcription factors are involved in PSKR1-mediated ripening. Yeast screening further identified that DEHYDRATION-RESPONSIVE ELEMENT BINDING PROTEIN 2F (DREB2F) interacts with PSKR1. Silencing of DREB2F delayed the initiation of fruit ripening and inhibited the promoting effect of PSK on fruit ripening. Moreover, the interaction between PSKR1 and DREB2F led to phosphorylation of DREB2F. PSK improved the efficiency of DREB2F phosphorylation by PSKR1 at the tyrosine-30 site, and the phosphorylation of this site increased the transcription level of potential target genes related to the ripening process and functioned in promoting fruit ripening and quality formation. These findings shed light on the involvement of PSK and its downstream signaling molecule DREB2F in controlling climacteric fruit ripening, offering insights into the regulatory mechanisms governing ripening processes in fleshy fruits.

To Investigate the Diagnostic Accuracy and Prognostic Value of Amplitude-Integrated Electroencephalography (aEEG) in Neonatal Hypoxic Ischemic Encephalopathy.

Objective: The objective of this study is to investigate the diagnostic accuracy and prognostic value of amplitude-integrated electroencephalography (aEEG) in neonatal hypoxic ischemic encephalopathy (HIE). Methods: Fifty-three neonates with HIE admitted to our hospital from February 2020 to September 2021 were included in the encephalopathy group, while 22 healthy neonates born in our hospital during the same period were included in the healthy group. The neonates were separated into three subgroups based on their aEEG results: normal, slightly abnormal, and severely abnormal. We investigated the correlation between aEEG monitoring and HIE clinical grading, as well as the rate of HIE abnormal prognosis, and we analyzed the prognostic value of aEEG in HIE. Results: The aEEGs of all neonates in the healthy group were normal. In the encephalopathy group, there were 24 neonates with normal aEEGs (including 20 with mild HIE and 4 with moderate HIE), 16 neonates with mildly abnormal aEEGs (including 4 with mild HIE, 10 with moderate HIE, and 2 with severe HIE), and 13 neonates with severely abnormal aEEGs (including 4 with moderate HIE and 9 with severe HIE). A very close correlation between aEEG monitoring results and HIE grading and prognosis was found (P < .05). The head circumference of neonates with severely abnormal aEEGs was smaller than that of the other two groups and was significantly smaller than that of the healthy group (P < .05). However, there was no significant difference in the body length and weight of neonates in the severely abnormal aEEG group when compared to other groups (P > .05). Conclusion: The brain function of neonates with HIE can be accurately diagnosed with aEEG, and this diagnostic technique has a crucial application value in the early diagnosis and prognosis evaluation of neonatal HIE.

Glucose sensing by regulator of G protein signaling 1 (RGS1) plays a crucial role in coordinating defense in response to environmental variation in tomato.

Low light intensities affect the outbreak of plant diseases. However, the underlying molecular mechanisms remain poorly understood. High-performance liquid chromatography analysis of tomato (Solanum lycopersicum) revealed that apoplastic glucose (Glc) levels decreased in response to low light. Conversely, low-light-induced susceptibility to Pseudomonas syringae pv tomato (Pst) DC3000 was significantly alleviated by exogenous Glc treatment. Using cell-based biolayer interferometry assays, we found that Glc specifically binds to the tomato regulator of G protein signaling 1 (RGS1). Laser scanning confocal microscopy imaging revealed that Glc triggers RGS1 endocytosis, which influences the uncoupling of the RGS1-Gα (GPA1) and GPA1-Gß (SlGB1) proteins, in a dose- and duration-dependent manner. Analysis of G protein single and double mutants revealed that RGS1 negatively regulates disease resistance under low light and is required for Glc-enhanced defense. Downstream of RGS1-Glc binding, GPA1 negatively mediates the light-intensity-regulated defense, whereas SlGB1 positively regulates this process. These results reveal a novel light-intensity-responsive defense system that is mediated by a Glc-RGS1-G protein signaling pathway. This information will be critical for future investigations of how plant cells sense extracellular sugars and adjust defense under different environments, as well as for genetic engineering approaches to improve stress resilience.

Ethylene response factors 15 and 16 trigger jasmonate biosynthesis in tomato during herbivore resistance.

Jasmonates (JAs) are phytohormones with crucial roles in plant defense. Plants accumulate JAs in response to wounding or herbivore attack, but how JA biosynthesis is triggered remains poorly understood. Here we show that herbivory by cotton bollworm (Helicoverpa armigera) induced both ethylene (ET) and JA production in tomato (Solanum lycopersicum) leaves. Using RNA-seq, ET mutants, and inhibitors of ET signaling, we identified ET-induced ETHYLENE RESPONSE FACTOR 15 (ERF15) and ERF16 as critical regulators of JA biosynthesis in tomato plants. Transcripts of ERF15 and ERF16 were markedly upregulated and peaked at 60 and 15 min, respectively, after simulated herbivore attack. While mutation in ERF16 resulted in the attenuated expression of JA biosynthetic genes and decreased JA accumulation 15 min after the simulated herbivory treatment, these changes were not observed in erf15 mutants until 60 min after treatment. Electrophoretic mobility shift assays and dual-luciferase assays demonstrated that both ERFs15 and 16 are transcriptional activators of LIPOXYGENASE D, ALLENE OXIDE CYCLASE, and 12-OXO-PHYTODIENOIC ACID REDUCTASE 3, key genes in JA biosynthesis. Furthermore, JA-activated MYC2 and ERF16 also function as the transcriptional activators of ERF16, contributing to dramatic increases in ERF16 expression. Taken together, our results demonstrated that ET signaling is involved in the rapid induction of the JA burst. ET-induced ERF15 and ERF16 function as powerful transcriptional activators that trigger the JA burst in response to herbivore attack.

High CO2 - and pathogen-driven expression of the carbonic anhydrase ßCA3 confers basal immunity in tomato.

Atmospheric CO2 concentrations exert a strong influence on the susceptibility of plants to pathogens. However, the mechanisms involved in the CO2 -dependent regulation of pathogen resistance are largely unknown. Here we show that the expression of tomato (Solanum lycopersicum) ß-CARBONIC ANHYDRASE 3 (ßCA3) is induced by the virulent pathogen Pseudomonas syringae pv. tomato DC3000. The role of ßCA3 in the high CO2 -mediated response in tomato and two other Solanaceae crops is distinct from that in Arabidopsis thaliana. Using ßCA3 knock-out and over-expression plants, we demonstrate that ßCA3 plays a positive role in the activation of basal immunity, particularly under high CO2 . ßCA3 is transcriptionally activated by the transcription factor NAC43 and is also post-translationally regulated by the receptor-like kinase GRACE1. The ßCA3 pathway of basal immunity is independent on stomatal- and salicylic-acid-dependent regulation. Global transcriptome analysis and cell wall metabolite measurement implicate cell wall metabolism/integrity in ßCA3-mediated basal immunity under both CO2 conditions. These data not only highlight the importance of ßCA3 in plant basal immunity under high CO2 in a well-studied susceptible crop-pathogen system, but they also point to new targets for disease management strategies in a changing climate.

Supine versus semi-Fowler's positions for tracheal extubation in abdominal surgery-a randomized clinical trial.

BACKGROUND: Tracheal extubation is commonly performed in the supine position. However, in patients undergoing abdominal surgery, the supine position increases abdominal wall tension, especially during coughing and deep breathing, which may aggravate pain and lead to abdominal wound dehiscence. The semi-Fowler's position may reduce abdominal wall tension, but its safety and comfort in tracheal extubation have not been reported. We aimed to evaluate the safety and comfort of different extubation positions in patients undergoing abdominal surgery. METHODS: We enrolled 141 patients with an American Society of Anesthesiologists grade of I-III who underwent abdominal surgery. All patients were anesthetized with propofol, fentanyl, cisatracurium, and sevoflurane. After surgery, all patients were transferred to the post-anesthesia care unit (PACU). Patients were then randomly put into the semi-Fowler's (n = 70) or supine (n = 71) position while 100% oxygen was administered. The endotracheal tube was removed after the patients opened their eyes and regained consciousness. Vital signs, coughing, and pain and comfort scores before and/or after extubation were recorded until the patients left the PACU. RESULTS: In comparison with the supine position, the semi-Fowler's position significantly decreased the wound pain scores at all intervals after extubation (3.51 ± 2.50 vs. 4.58 ± 2.26, 2.23 ± 1.68 vs. 3.11 ± 2.00, 1.81 ± 1.32 vs. 2.59 ± 1.88, P = 0.009, 0.005 and 0.005, respectively), reduced severe coughing (8[11.43%] vs. 21[29.58%], P = 0.008) and bucking after extubation (3[4.29%] vs. 18[25.35%], P < 0.001), and improved the comfort scores 5 min after extubation (6.11 ± 2.30 vs. 5.17 ± 1.78, P = 0.007) and when leaving from post-anesthesia care unit (7.17 ± 2.27 vs. 6.44 ± 1.79, P = 0.034). The incidences of vomiting, emergence agitation, and respiratory complications were of no significant difference. CONCLUSION: Tracheal extubation in the semi-Fowler's position is associated with less coughing, sputum suction, and pain, and more comfort, without specific adverse effects when compared to the conventional supine position. TRIAL REGISTRATION: Chinese Clinical Trial Registry, ChiCTR1900025566 . Registered on 1st September 2019.

Role of ethylene biosynthesis and signaling in elevated CO2-induced heat stress response in tomato.

MAIN CONCLUSION: This article unveiled that ethylene biosynthesis and signaling play a critical role in heat stress response of tomato plants under elevated CO2. Plant responses to elevated CO2 and heat stress are tightly regulated by an intricate network of phytohormones. Plants accumulate ethylene (ET), the smallest hormone, in response to heat stress; however, the role of ET and its signaling in elevated CO2-induced heat stress response remains largely unknown. In this study, we found that transcript levels of multiple genes relating to ET synthesis, signaling, and heat shock proteins (HSPs) were induced by elevated CO2 (800 µmol mol-1) compared to ambient CO2 (400 µmol mol-1) in tomato leaves under controlled temperature conditions (25 °C). Elevated CO2-induced responses to heat stress (42 °C) were closely associated with increased ET production and HSP70 expression at both transcript and protein levels. Pretreatment with an antagonist of ET, 1-methylcyclopropene that inhibits ET-dependent responses, abolished elevated CO2-induced stress response without affecting the ET production rate. In addition, silencing of ethylene response factor 1 (ERF1) compromised elevated CO2-induced responses to heat stress, which was associated with the concomitant reduction in the transcript of heat shock factor A2, HSP70 and HSP90, indicating that ERF1 is required for elevated CO2-induced responses to heat. All these results provide convincing evidence on the importance of ET biosynthesis and signaling in elevated CO2-induced heat stress response in tomato plants. Thus, the study advances our understanding of the mechanisms of elevated CO2-induced stress response and may potentially be useful for breeding heat-tolerant tomatoes in the era of climate change.

Stomatal movements are involved in elevated CO2 -mitigated high temperature stress in tomato.

Climate changes such as heat waves often affect plant growth and pose a growing threat to natural and agricultural ecosystems. Elevated atmospheric CO2 can mitigate the negative effects of heat stress, but the underlying mechanisms remain largely unclear. We examined the interactive effects of elevated CO2 (eCO2 ) and temperature on the generation of the hydrogen peroxide (H2 O2 ) and stomatal movement characteristics associated with heat tolerance in tomato seedlings grown under two CO2 concentrations (400 and 800 µmol mol-1 ) and two temperatures (25 and 42°C). eCO2 ameliorated the negative effects of heat stress, which was accompanied by greater amounts of RESPIRATORY BURST OXIDASE 1 (RBOH1) transcripts, apoplastic H2 O2 accumulation and decreased stomatal aperture. Silencing RBOH1 and SLOW-TYPE ANION CHANNEL, impeded eCO2 -induced stomatal closure and compromised the eCO2 -enhanced water use efficiency as well as the heat tolerance. Our findings suggest that RBOH1-dependent H2 O2 accumulation was involved in the eCO2 -induced stomatal closure, which participate in maintaining balance between water retention and heat loss under eCO2 concentrations. This phenomenon may be a contributor to eCO2 -induced heat tolerance in tomato, which will be critical for understanding how plants respond to both future climate extremes and changes in CO2 .

Correction: The novel leucine-rich repeat receptor-like kinase MRK1 regulates resistance to multiple stresses in tomato.

[This corrects the article DOI: 10.1093/hr/uhab088.].

A novel leucine-rich repeat receptor-like kinase MRK1 regulates resistance to multiple stresses in tomato.

Leucine-rich repeat receptor-like kinases (LRR-RLKs) are ubiquitous in higher plants, which act as receptors of extracellular signals to trigger multiple physiological processes. However, the functions of the majority of LRR-RLKs remain largely unknown, especially in tomato (Solanum lycopersicum L.). Here, we found that MRK1 (Multiple resistance-associated kinase 1), encoding a novel tomato LRR-RLK, was significantly induced either by temperature stresses or bacterial pathogen attacks. Knocking out MRK1 impaired the tolerance to both cold and heat stress, accompanied with the decrease in transcripts of master regulators C-repeat binding factor 1 (CBF1) and Heat shock transcription factor a-1a (HsfA1a), respectively. Additionally, mrk1 mutants were hypersensitive to Pseudomonas syringae pv. tomato DC3000 and Ralstonia solanacearum and compromised pattern-triggered immunity (PTI) responses as evidenced by decreased reactive oxygen species production and reduced upregulation of the PTI marker genes. Moreover, bimolecular fluorescence complementation, split-luciferase assay and coimmunoprecipitation supported the existence of complex formation between the MRK1, FLS2 and Somatic embryogenesis receptor kinase (SERK3A/SERK3B) in a ligand-independent manner. This work demonstrates that tomato MRK1 as a novel positive regulator of multiple stresses, which might be a potential breeding target to improve crop stress resistance.

An Essential Role of Mitochondrial α-Ketoglutarate Dehydrogenase E2 in the Basal Immune Response Against Bacterial Pathogens in Tomato.

Plants intensely modulate respiration when pathogens attack, but the function of mitochondrial respiration-related genes in plant-bacteria interaction is largely unclear. Here, the functions of α-ketoglutarate dehydrogenase (α-kGDH) E2 subunit and alternative oxidase (AOX) were investigated in the interaction between tomato and the virulent bacterial pathogen Pseudomonas syringae pv. tomato DC3000 (Pst). Pst inoculation suppressed the transcript abundance of α-kGDH E2, but enhanced AOX expression and salicylic acid (SA) accumulation. Gene silencing and transient overexpression approaches revealed that plant susceptibility to Pst was significantly reduced by silencing α-kGDH E2 in tomato, but increased by overexpressing α-kGDH E2 in Nicotiana benthamiana, whereas silencing or overexpressing of AOX1a did not affect plant defense. Moreover, silencing octanoyltransferase (LIP2), engaged in the lipoylation of α-kGDH E2, significantly reduced disease susceptibility and hydrogen peroxide accumulation. Use of transgenic NahG tomato plants that cannot accumulate SA as well as the exogenous SA application experiment evidenced that α-kGDH E2 acts downstream of SA defense pathway. These results demonstrate tomato α-kGDH E2 plays a negative role in plant basal defense against Pst in an AOX-independent pathway but was associated with lipoylation and SA defense pathways. The findings help to elucidate the mechanisms of mitochondria-involved plant basal immunity.

[Hyperbaric oxygen improves long-term learning-memory deficits and brain injury in neonatal rat with hypoxia-ischemia brain damage].

OBJECTIVE: To investigate the effect of hyperbaric oxygen (HBO) on long-term learning-memory disabilities and brain injury induced by hypoxia-ischemia in neonatal rat. METHODS: In the study, eighteen rats aged seven days were divid into three groups: (1) sham-operated group (SHAM), (2) hypoxia-ischemia group (HIBD), (3) HBO-treated hypoxia-ischemia group (HIBD + HBO). In hypoxia-ischemia groups, left common carotid artery was ligated permanently on the seventh postnatal day, two hours after the procedure; hypoxia (92% nitrogen and 8% oxygen) was induced for 2 h. In HBO-treated hypoxia-ischemia group, single HBO (2. 5 ATA, 1.5 h) was administered at one hour after the hypoxia period. At the six weeks old, step-down inhibitory avoidance test was used to evaluate the short-term memory of rats. Learning and long-term spatial memory deficits were tested using Morris water maze at eight weeks old of rats. Rats were then perfused and brains removed for macroscopic and microscopic evaluation. The cell density of hippocampus were used to evaluate the degree of brain injure. RESULTS: In HIBD+HBO group, the latency to step down the platform was significantly longer than that of HIBD group (P<0.05); in HIBD+HBO group, the mean latencies to reach the platform was significantly shorter than that of HIBD group (P < 0.05); in HIBD + HBO group, the time spent in the target quadrant was significantly lower than that in HIBD group (P<0.05). Histopathological evaluation demonstrated that HBO also significantly diminished brain injury and decreased the cell loss of hippocampal CA1 region. CONCLUSION: Single HBO (2.5 ATA, 1.5 h) can significantly improve long-term learning-memory deficits and attenuate brain injury in rats with hypoxia-ischemia brain damage.

Thymosin ß4 inhibits microglia activation through microRNA 146a in neonatal rats following hypoxia injury.

Neuroinflammation mediated by activated microglia plays a pivotal role in the pathogenesis of neurological disorders, including hypoxic injury of the developing brain. Thymosin ß4 (Tß4), the major G-actin-sequestering molecule, has an anti-inflammatory effect and has been used to treat various neurological diseases. However, the effect of Tß4 on hypoxia-induced microglia activation in the developing brain remains unclear. We investigate here the effect of Tß4 on microglia activation of neonatal rats after hypoxia exposure. Tß4 treatment was carried out on 1-day-old rats and BV-2 cells. Tß4 expression in microglia was determined by quantitative real time-PCR, western blotting, and immunofluorescence staining. Secretion of tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß), and nitric oxide (NO) was assessed by enzyme-linked immunosorbent assay and colorimetric assay. mRNA expression of TNF-α and IL-1ß, and microRNA 146a expression was determined by quantitative real time-PCR. We showed that Tß4 treatment significantly inhibited secretion of inflammatory mediators in the cerebellum of neonatal rats following hypoxia injury. Increased expression of endogenous Tß4 in microglia was observed both in hypoxic rats and in BV-2 cells. Tß4 treatment significantly inhibited the expression and secretion of hypoxia-induced TNF-α, IL-1ß, and NO. Remarkably, microRNA 146a expression was found to have increased in Tß4-treated BV-2 cells. We demonstrated the anti-inflammatory effect of Tß4 in neonatal rats following hypoxic brain injury. More importantly, our data reveal, for the first time, that Tß4 inhibits microglia activation in vitro. Therefore, this study contributes to understanding the role and mechanism of Tß4 function in central nervous system diseases.

Transcatheter closure of congenital perimembranous ventricular septal defect in children using symmetric occluders: an 8-year multiinstitutional experience.

BACKGROUND: Perimembranous ventricular septal defects (pmVSDs) are one of the most common forms of congenital cardiac malformation in children. Results of transcatheter pmVSD closure remain debatable, prompting the need for further evaluation with regard to the safety and efficacy of this procedure. The aim of the study was to analyze the safety, efficacy, and long-term follow-up data associated with transcatheter closure of pmVSDs in children using symmetric occluders. METHODS: From December 2002 to October 2011, 525 children with pmVSDs between 2 and 12 years of age underwent transcatheter closure at three major heart centers in northwest China with symmetric pmVSD occluders. All patients were followed up until October 2011 with electrocardiogram and transthoracic echocardiography. Adverse events were recorded and evaluated. RESULTS: There were 252 male and 273 female patients with an average weight of 21.5 kg. The mean age at the time of transcatheter closure was 5.6 years, and the average ratio of pulmonic to systemic blood flow was 2.5. Transcatheter intervention was successfully performed in 502 patients (95.6%). The median device size implanted was 6.5 mm (range, 4 to 18 mm). During a median 45-month follow-up period, no mortality occurred. A total of three major adverse events (0.6%) were reported; two were valve-related. Meanwhile, 104 minor adverse events were detected during the entire follow-up period. All individuals experiencing major adverse events were younger than 3 years of age. The incidence of major adverse events in patients younger than 3 years old was significantly higher than that of patients older than 3 years old (3.75% versus 0.00%; Fisher's exact test p=0.004). CONCLUSIONS: Data from the current study suggest that transcatheter pmVSD closure using symmetric occluders displayed an excellent success rate and long-term follow-up results. The transcatheter approach provides a less-invasive alternative to open surgery and displays some promise in the treatment of pmVSDs in certain patient populations.

Transcatheter closure of perimembranous ventricular septal defect in a patient with abnormal inferior vena cava return.

An 8-year-old boy with a 3.8 mm perimembranous ventricular septal defect (PmVSD) and abnormal inferior vena cava return was attempted cardiac catheterization to occlude the VSD. Through the right jugular vein and right femoral artery approach, an 8 mm Amplatzer VSD occluder was successfully deployed under fluoroscopic and echocardiographic guidance. After a 2 year follow-up, the patient is symptom-free. Our report offers a new perspective to percutaneous treatment of PmVSD with abnormal inferior vena cava return.

[Optimal therapeutic window of hyperbaric oxygenation in neonatal rat with hypoxic-ischemic brain damage].

OBJECTIVE: Hyperbaric oxygenation (HBO) is an attractive procedure that has been used in treatment of hypoxic-ischemic encephalopathy (HIE). However, depending on the HBO protocol, especially the time point of starting treatment of HBO, different and conflicting results were obtained. This study was undertaken to search for the optimal therapeutic window of ABO in neonatal rat with hypoxic-ischemic brain damage (HIBD). METHODS: Eighty-four healthy seven-day-old SD rats were used as research subjects and were randomly divided into seven groups with 12 in each: sham group, HI group, HI (1 h) + HBO group (HBO starting 1 h after HI), HI (3 h) + HBO group (HBO starting 3 h after HI), HI (6 h) + HBO group (HBO starting 6 h after HI), HI (12 h) + HBO group (HBO starting 12 h after HI), HI (24 h) + HBO group (HBO starting 24 h after HI). Single HBO treatment (2.5 atmospheres absolute, ATA for 1.5 h) was used in this study. Two indexes were used to assess the effect of HBO that included short-term (48 h after HI) histology change (the cell density in CA1 of hippocampus and cortex) and long-term (5 w and 6 w after HI) neurobehavioral testing (grip test and treadmill test for evaluating the deficits of sensor motor; step-down avoidance test for assessing the deficits of memory). RESULTS: In HI (1 h) + HBO, HI (3 h) + HBO and HI (6 h) + HBO groups, neuron density of cortex and CA1 of hippocampus were 1981.76 +/- 299.55, 1841.53 +/- 241.21, 1525.78 +/- 189.00 and 4430.56 +/- 1180.31, 4507.54 +/- 1374.32, 3883.48 +/- 821.87, respectively, which were significantly higher than HIBD group (987.86 +/- 285.39 and 1813.59 +/- 295.33, P < 0.05, ANOVA). But in HI (12 h) + HBO and HI (24 h) + HBO, the neuron density of cortex and CA1 of hippocampus compared with those in HIBD group had no statistical significance (P > 0.05, ANOVA). In the sensor motor testing performed at 5 w after HI of rat, the grip time in grip test and the stay time in treadmill test of HI (1 h) + HBO, HI (3 h) + HBO and HI (6 h) + HBO groups were 193.39 +/- 51.19, 168.39 +/- 34.02, 168.95 +/- 34.93 and 130.34 +/- 42.56, 128.20 +/- 27.69, 125.74 +/- 36.99, respectively, which, compared with HIBD group, were significantly prolonged (P < 0.05, ANOVA). But in HI (12 h) + HBO and HI (24 h) + HBO groups, the time was not significantly longer compared with HI (P > 0.05, ANOVA). In the step-down avoidance test which was performed at 6 w after HI, the step-down latencies of HI (1 h) + HBO, HI (3 h) + HBO and HI (6 h) + HBO were 96.91 +/- 29.91, 90.35 +/- 28.44 and 76.46 +/- 38.70, respectively, which were significantly prolonged (P < 0.05, ANOVA), but in HI (12 h) + HBO and HI (24 h) + HBO, the latencies did not significantly increase compared with HIBD, P > 0.05, ANOVA. CONCLUSIONS: The optimal therapeutic window of HBO in neonatal rat with HIBD was within the first 6 hours after HI. In this therapeutic window, HBO was highly effective in reducing the cell loss in CA1 of hippocampus and cortex.