Graduate Student Literature Review: Developmental adaptations of immune function in calves and the influence of the intestinal microbiota in health and disease.

This graduate student literature review provides an examination of the ontological adaptations of the calf's immune system and how the intestinal microbiota influences calf immune function in health and disease. Within dairy rearing systems, various nutritional and management factors have emerged as critical determinants of development influencing multiple physiological axes in the calf. Furthermore, we discuss how multiple pre- and postnatal maternal factors influence the trajectory of immune development in favor of establishing regulatory networks to successfully cope with the new environment, while providing early immune protection via immune passive transfer from colostrum. Additionally, our review provides insights into the current understanding of how the intestinal microbiota contributes to the development of the intestinal and systemic immune system in calves. Lastly, we address potential concerns related to the use of prophylactic antimicrobials and waste milk, specifically examining their adverse effects on intestinal health and metabolic function. By examining these factors, we aim to better understand the intricate relationship between current management practices and their long-term effect on animal health.

Dynamics of oxidative stress and immune responses in neonatal calves during diarrhea.

Oxidative stress is the imbalanced redox status between oxidant production and their scavengers leading to intestinal physiological dysfunction. However, the role of systemic and local oxidative status during neonatal calf diarrhea is not known. This study assessed systemic (serum) and local (fecal) oxidative status when calves either naturally developed diarrhea or naturally recovered. Healthy calves were enrolled in the study at d 18 of age, and their health status was monitored from the enrollment. Based on their enteric health status on d 21 and 28, calves were grouped as continuous diarrhea from d 21 to 28 (n = 14), diarrhea at d 21 but recovered at d 28 (DH group, n = 19), healthy at d 21 but developed diarrhea at d 28 (HD group, n = 15), and healthy throughout the study (HH group, n = 16). Serum and fecal samples were collected at d 21 and 28 from all calves in the morning 2 h after feeding. Dynamics of oxidative stress indicators including reactive oxygen species (ROS), malondialdehyde (MDA), H2O2, 8-hydroxy-2'-deoxyguanosine (8-OHDG), glutathione peroxidase, superoxide dismutase, catalase (CAT), and total antioxidant capacity and inflammatory indicators TNF-α, IL-1ß, IL-4, IL-6, IL-10, and IFN-γ were evaluated using serum samples. In addition, fecal oxidative stress indicators ROS and MDA were measured. Serum ROS, MDA, 8-OHDG, as well as fecal ROS and MDA, were higher, whereas serum CAT and H2O2 were lower in diarrheic calves than those of healthy calves. Serum ROS, MDA, and 8OHDG and fecal ROS and MDA increased in the HD group from d 21 to 28 as they developed diarrhea. In contrast, all these oxidative stress markers decreased in the DH group from d 21 to 28 as they recovered. However, serum H2O2 had an opposite changing trend, which became lower in the HD group and higher in the DH group at d 28. In conclusion, both systemic and local oxidative stress markers and cytokine profiles altered as calves moved from being healthy to having diarrhea or vice versa. Serum ROS, MDA, and 8-OHDG can be used to develop biomarkers to screen calves prone to enteric infections during the preweaning period.

[Clinical research progress in non-invasive positive pressure ventilation in 2023].

Non-invasive positive pressure ventilation (NPPV) is a widely used method of providing respiratory support in a variety of clinical settings, including emergency departments, general wards, and intensive care units. The relevant research articles on NPPV published between 1st October 2022 and 30th September 2023 were retrieved from Medline and reviewed. In the management of acute respiratory failure (ARF) associated with COVID-19, studies have highlighted the significant influence of regional economic status on the choice of respiratory support strategies. It has been observed that NPPV is more suitable for patients with mild to moderate acute respiratory distress syndrome (ARDS) than for those with severe ARDS, as the latter group has an increased risk of delayed intubation. In addition, patients with severe dyspnea tended to benefit more from NPPV compared with high flow nasal cannula (HFNC) and conventional oxygen therapy, with a reduced risk of self-induced lung injury. For non-COVID-19-related ARF, research shows no significant differences in mortality and intubation rates between HFNC and NPPV in patients with hypercapnic ARF. The updated HACOR score and ROX score have been validated to have a high predictive value for clinical outcomes in patients receiving NPPV for hypoxemic ARF. With regard to weaning from invasive mechanical ventilation, immediate application of NPPV after extubation showed a lower mortality rate compared to continued invasive weaning. Moreover, NPPV with active humidification significantly decreased the reintubation rate within 7 days after extubation compared with HFNC. The choice between using NPPV and HFNC should be based on the specific etiology of the patient's condition. The potential effect of noninvasive high-frequency oscillatory ventilation on CO2 clearance was also investigated.

[The occupational exposure prevention and control system for hazardous drugs in the United States].

Hazardous drugs represented by antineoplastic drugs have clear health hazards to occupational exposed populations, and this issue has received widespread attention all over the world in recent years. This article reviewed the laws, regulations, guidelines, and industry guidance documents for the prevention and control of occupational exposure to hazardous drugs issued by relevant departments and associations in the United States. It could provide a reference basis for the development of occupational environmental health standards and protection guidelines, with the aim of reducing the risk of occupational exposure to hazardous drugs and promoting the healthy development of healthcare services in China.

Maternal rumen and milk microbiota shape the establishment of early-life rumen microbiota in grazing yak calves.

Early-life gut microbial colonization and development exert a profound impact on the health and metabolism of the host throughout the life span. The transmission of microbes from the mother to the offspring affects the succession and establishment of the early-life rumen microbiome in newborns, but the contributions of different maternal sites to the rumen microbial establishment remain unclear. In the present study, samples from different dam sites (namely, oral, rumen fluid, milk, and teat skin) and rumen fluid of yak calves were collected at 6 time points between d 7 and 180 postpartum to determine the contributions of the different maternal sites to the establishment of the bacterial and archaeal communities in the rumen during early life. Our analysis demonstrated that the dam's microbial communities clustered according to the sites, and the calves' rumen microbiota resembled that of the dam consistently regardless of fluctuations at d 7 and 14. The dam's rumen microbiota was the major source of the calves' rumen bacteria (7.9%) and archaea (49.7%) compared with the other sites, whereas the potential sources of the calf rumen microbiota from other sites varied according to the age. The contribution of dam's rumen bacteria increased with age from 0.36% at d 7 to 14.8% at d 180, whereas the contribution of the milk microbiota showed the opposite trend, with its contribution reduced from 2.7% at d 7 to 0.2% at d 180. Maternal oral archaea were the main sources of the calves' rumen archaea at d 14 (50.4%), but maternal rumen archaea became the main source gradually and reached 66.2% at d 180. These findings demonstrated the potential microbial transfer from the dam to the offspring that could influence the rumen microbiota colonization and establishment in yak calves raised under grazing regimens, providing the basis for future microbiota manipulation strategies during their early life.

[Clinical update in non-invasive positive pressure ventilation for respiratory failure in 2022].

In this article, we searched the research literatures related to clinical investigation of non-invasive positive pressure ventilation (NPPV) in acute respiratory failure(ARF)/chronic respiratory failure(CRF) between 1st October 2021 and 30th September 2022 through Medline, and reviewed the important advances. Three prospective randomized controlled studies related to the efficacy and safety of NPPV and/or high-flow nasal cannula oxygen therapy (HFNC) on patients with COVID-19 with ARF were reported, showing that NPPV (including continuous positive airway pressure and bilevel positive airway pressure) was able to reduce the intubation rate, but the efficacy of HFNC was contradictory. In addition, progress has been made in outcome prediction models for ARF treated with NPPV, NPPV-related cardiac arrest, and the impact of human-machine interface on NPPV treatment outcomes. The effects of NPPV as preoxygenation method before intubation was reported to be able to reduce severe desaturation during intubation, especially in obese population. The use of NPPV in extubated patients resulting in reduced reintubation rate was also studied. With regard to long-term home application of NPPV, five indicators of successful initiation were proposed, but the success rate was low in clinical practice. Some reports showed that psychological support could improve the adherence to NPPV. The results of these studies contributed to the rational selection and optimal application of NPPV in clinical practice.

[Research progress on head imaging features of carbon monoxide poisoning and delayed encephalopathy].

Acute carbon monoxide poisoning and its delayed encephalopathy have obvious damage to the central nervous system. There are different neuroimaging changes in different stages of the disease, and they are relatively specific. This article reviews the clinical research progress on the imaging changes of carbon monoxide poisoning and delayed encephalopathy, including computed tomography (CT) , conventional magnetic resonance imaging (MRI) , diffusion weighted imaging (DWI) , diffusion tensor imaging (DTI) , diffusion kurtosis imaging (DKI) , magnetic resonance spectroscopy (MRS) and other imaging changes reflecting the function and metabolic state of the brain tissue.

[Application of artificial intelligence in digital chest radiography diagnosis of pneumoconiosis].

Pneumoconiosis is the occupational disease with the highest burden in China currently. The diagnosis of pneumoconiosis mainly relies on manual reading of X-ray high-kilovoltage or digital photography chest radiograph, which has some problems such as low efficiency, strong subjectivity, and cannot accurately judge the critical lesions. With the progress of machine-aided diagnosis technology, the efficient, objective and quantitative of artificial intelligence diagnosis technology just solve the shortcomings above. This paper reviews the research progress in digital chest radiography diagnosis of pneumoconiosis using artificial intelligence technology, especially deep learning model, combined with the limitations of conventional manual reading, in order to clarify the application prospect of artificial intelligence technology in the diagnosis of pneumoconiosis by digital chest radiography, and provide a direction for future research in this field.

[Analysis on the quality control of suspected occupational disease from the characteristics of applicants diagnosed with noise deafness].

Objective: To analyze the audiology and occupational health data of applicants diagnosed of occupational noise deafness, and to explore the influencing factors in the diagnosis of suspected occupational noise deafness. Methods: In May 2022, the information of patients diagnosed with occupational noise deafness in Peking University Third Hospital from January 2018 to December 2021 was collected, and the occupational health data of their working environment, clinical audiological examination results and diagnosis basis of occupational noise deafness were collected and analyzed. Multi-factor unconditional logistic regression analysis was used to analyze independent risk factors for the diagnosis of occupational noise deafness. Results: A total of 129 subjects were included, all of which were suspected cases of occupational noise deafness found in various occupational health examination institutions. Eight cases (6.20%) were diagnosed as occupational noise deafness, and 121 cases (93.80%) were non-occupational noise deafness. After hearing examination, only 27.27% (24/88) of the patients' audiological changes were consistent with the starting point of occupational noise deafness diagnosis. Further analysis of the noise intensity in the workplace showed that 16 patients were identified as non-occupational noise deafness because the noise intensity of the working environment was less than 85 dB. Logistic regression analysis showed that the working hours were more than 8 hours (OR=9.274, 95%CI: 1.388-61.950, P=0.022) and the noise intensity of the working environment (OR=1.189, 95%CI: 1.059-1.334, P=0.003) were independent risk factors for the diagnosis of occupational noise deafness. Conclusion: The exclusion rate of suspected occupational noise deafness found in occupational health examination is higher after adequate rest. The test results of working environment noise intensity provided by the employer can help to determine occupational noise deafness.

[Analysis on characteristic of stage â occupational cement pneumoconiosis patients].

Objective: To analyze the clinical and imaging characteristics of stage Ⅰ occupational cement pneumoconiosis patients. Methods: In October 2021, the data of patients with occupational cement pneumoconiosis diagnosed by the Third Hospital of Peking University from 2014 to 2020 were collected, and the data of the patients' initial exposure age, dust exposure duration, diagnosis age, incubation period, chest X-ray findings, lung function and other data were analyzed retrospectively. Spearman grade correlation was used for correlation analysis of grade count data. The influencing factors of lung function were analyzed by binary logistic regression. Results: A total of 107 patients were enrolled in the study. There were 80 male patients and 27 female patients. The inital exposure age was (26.2±7.7) years, the diagnosis age was (59.4±7.9) years, the dust exposure duration was (17.9±8.0) years, and the incubation period was (33.1±10.3) years. The initial dust exposure age and the dust exposure duration in female patients were less than those in men, and the incubation period was longer than that in men (P<0.05). The imaging analysis showed the small opacities as"pp"accounted for 54.2%. 82 patients (76.6%) had small opacities distributed in two lung areas. The lung areas distribution of small opacities in female patients was less than that in male patients (2.04±0.19 vs 2.41±0.69, P<0.001). There were 57 cases of normal pulmonary function, 41 cases of mild abnormality and 9 cases of moderate abnormality. The number of lung regions with small opacities on X-ray was the risk factor for abnormal lung function in cement pneumoconiosis patients (OR=2.491, 95%CI=1.197-5.183, P=0.015) . Conclusion: The patients with occupational cement pneumoconiosis had long dust exposure duration and incubation period, light imaging changes and pulmonary function damage. The abnormal lung function was related to the range of pulmonary involvement.

[Drug clinical comprehensive evaluation of tetrandrine in the treatment of pneumoconiosis].

Objective: To analyze the safety, effectiveness, economics, innovation, suitability and accessibility of tetrandrine in the treatment of pneumoconiosis, and provide evidence-based basis for health policy decision-making and clinical practice. Methods: In July 2022, the system searched PubMed, Embase, the Cochrane Library, CNKI, Wanfang, SinoMed databases (the retrieval time was from the establishment of the database to June 30, 2022), screened the documents that meet the standards, extracted and evaluated the data, and used the "HTA checklist" developed by the International Network of Agencies for Health Technology Assessment (INAHTA) to evaluate the HTA report. AMSTAR-2 Scale was used to evaluate the quality of systematic evaluation/Meta analysis. CHEERS Scale was used to evaluate the quality of pharmacoeconomics research. The included cohort study or case-control study was evaluated with the Newcastle-Ottawa Scale. The included randomized controlled trial (RCT) studies were evaluated using the Cochrane Risk Bias Assessment Tool (Cochrane RCT) quality evaluation criteria. Comprehensive comparison and analysis based on the characteristics of the data included in the study. Results: A total of 882 related literatures were detected from the initial screening. According to relevant standards, 8 RCT studies were finally selected for analysis. Statistical results showed that basic treatment with tetrandrine could better improve FEV(1) (MD=0.13, 95%CI: 0.06-0.20, P<0.001), FEV(1)/FVC (MD=4.48, 95%CI: 0.61-8.35, P=0.02) and clinical treatment efficiency. Tetrandrine had a low incidence of adverse reactions. The affordability coefficient of tetrandrine tablets was 0.295-0.492. Conclusion: Tetrandrine can improve the clinical symptoms and pulmonary ventilation function of pneumoconiosis patients, most of the adverse reactions are mild, and the clinical application is safe.

Invited review: Effect of subacute ruminal acidosis on gut health of dairy cows.

Subacute ruminal acidosis (SARA) is assumed to be a common disease in high-yielding dairy cows. Despite this, the epidemiological evidence is limited by the lack of survey data. The prevalence of SARA has mainly been determined by measuring the pH of ruminal fluid collected using rumenocentesis. This may not be sufficiently accurate, because the symptoms of SARA are not solely due to ruminal pH depression, and ruminal pH varies among sites in the rumen, throughout a 24-h period, and among days. The impact of SARA has mainly been studied by conducting SARA challenges in cows, sheep, and goats based on a combination of feed restriction and high-grain feeding. The methodologies of these challenges vary considerably among studies. Variations include differences in the duration and amount of grain feeding, type of grain, amount and duration of feed restriction, number of experimental cows, and sensitivity of cows to SARA challenges. Grain-based SARA challenges affect gut health. These effects include depressing the pH in, and increasing the toxin content of, digesta. They also include altering the taxonomic composition of microbiota, reducing the functionality of the epithelia throughout the gastrointestinal tract (GIT), and a moderate inflammatory response. The effects on the epithelia include a reduction in its barrier function. Effects on microbiota include reductions in their richness and diversity, which may reduce their functionality and reflect dysbiosis. Changes in the taxonomic composition of gut microbiota throughout the GIT are evident at the phylum level, but less evident and more variable at the genus level. Effects at the phylum level include an increase in the Firmicutes to Bacteroidetes ratio. More studies on the effects of a SARA challenge on the functionality of gut microbiota are needed. The inflammatory response resulting from grain-based SARA challenges is innate and moderate and mainly consists of an acute phase response. This response is likely a combination of systemic inflammation and inflammation of the epithelia of the GIT. The systemic inflammation is assumed to be caused by translocation of immunogenic compounds, including bacterial endotoxins and bioamines, through the epithelia into the interior circulation. This translocation is increased by the increase in concentrations of toxins in digesta and a reduction of the barrier function of epithelia. Severe SARA can cause rumenitis, but moderate SARA may activate an immune response in the epithelia of the GIT. Cows grazing highly fermentable pastures with high sugar contents can also have a low ruminal pH indicative of SARA. This is not accompanied by an inflammatory response but may affect milk production and gut microbiota. Grain-based SARA affects several aspects of gut health, but SARA resulting from grazing high-digestible pastures and insufficient coarse fiber less so. We need to determine which method for inducing SARA is the most representative of on-farm conditions.

Effects of replacing inorganic salts of trace minerals with organic trace minerals in pre- and postpartum diets on feeding behavior, rumen fermentation, and performance of dairy cows.

Our objectives were to evaluate the effects of complete replacement of supplementary inorganic salts of trace minerals (STM) by organic trace minerals (OTM) in both pre- and postpartum diets on feeding behavior, ruminal fermentation, rumination activity, energy metabolism, and lactation performance in dairy cows. Pregnant cows and heifers (n = 273) were blocked by parity and body condition score and randomly assigned to either STM or OTM diets at 45 ± 3 d before their expected calving date. Both groups received the same diet, except for the source of trace minerals (TM). The STM group was supplemented with Co, Cu, Mn, and Zn sulfates and Na selenite, whereas the OTM group was supplemented with Co, Cu, Mn, and Zn proteinates and selenized yeast. Treatments continued until 156 days in milk and pre- and postpartum diets were formulated to meet 100% of recommended levels of each TM in both treatments, taking into consideration both basal and supplemental levels. Automatic feed bins were used to assign treatments to individual cows and to measure feed intake and feeding behavior. Rumination activity was monitored by sensors attached to a collar from wk -3 to 3 relative to calving. Blood metabolites were evaluated on d -21, -10, -3, 0, 3, 7, 10, 14, 23, and 65 relative to calving. Ruminal fluid samples were collected using an ororuminal sampling device on d -21, 23, and 65 relative to calving, for measurement of ruminal pH and concentration of volatile fatty acids. Cows were milked twice a day and milk components were measured monthly. Cows supplemented with OTM tended to have longer daily feeding time (188 vs. 197 min/d), and greater dry matter intake (DMI; 12.9 vs. 13.3 kg), and had a more positive energy balance (3.6 vs. 4.2 Mcal/d) and shorter rumination time per kg of dry matter (DM; 40.1 vs. 37.5 min/kg of DM) than cows supplemented with STM during the prepartum period. In the postpartum period, OTM increased DMI in multiparous cows (24.1 vs. 24.7 kg/d) but not in primiparous cows (19.1 vs. 18.7 kg/d). The difference in DMI of multiparous cows was more evident in the first 5 wk of lactation, when it averaged 1 kg/d. Milk yield was not affected by treatment in multiparous cows (44.1 vs. 44.2 kg/d); however, primiparous cows supplemented with OTM had lesser yields than primiparous cows supplemented with STM (31.9 vs. 29.8 kg/d). Cows supplemented with OTM had a greater percentage of protein in milk (3.11 vs. 3.17%), reduced concentration of nonesterified fatty acids in serum (0.45 vs. 0.40 mmol/L), and rumination activity (30.1 vs. 27.8 min/kg of DM) than cows supplemented with STM. At the end of the transition period, cows supplemented with OTM had reduced molar proportion of acetate, reduced pH, and tended to have a greater concentration of total volatile fatty acids in ruminal fluid. In conclusion, complete replacement of STM by OTM caused modest changes in rumen fermentation, feeding behavior, energy metabolism, and performance of dairy cows, improving postpartum DMI in multiparous cows and reducing circulating levels of nonesterified fatty acids. The pre-absorptive effects of TM source and the parity specific responses on performance warrant further research.

[Application of cortical bone trajectory screw and sacral alar screw internal fixation for surgical treatment of lumbar adjacent segment degeneration].

Objective: To explore the application of cortical bone trajectory screw (CBTS) and sacral alar screw (SAS) internal fixation in the treatment of lumbar adjacent segment degeneration (ASD) and evaluate its clinical effect. Methods: Data of 24 patients who were diagnosed with ASD and treated by CBTS or SAS in Beijing Chaoyang Hospital were retrospectively reviewed. There were 14 males and 10 females with a mean age of (67.9±8.2) years. The patients were followed-up for (2.6±0.4) years. Perioperative parameters including operation time, intraoperative blood loss and postoperative time on the ground were counted. All patients were followed-up for at least 2 years. Visual analogue scale (VAS) and the Oswestry disability index (ODI) were compared between pre-operation and at the last follow-up. The internal fixation-related complications, pseudarthrosis and adjacent re-degeneration were evaluated in the follow-up. Results: There were 14 proximal ASD patients, 8 distal ASD patients, 1 both ends ASD patient and 1 ASD patient in between the fusion surgeries. Bone mineral density (BMD) T score of the adjacent vertebrae was -1.98±0.91 on average. The ASD patients were re-operated with CBTS and SAS internal fixation technique. A small incision was made in the revision surgery and the original fixation was not completely cut open and removed. The mean operation time was (125±36) min, mean blood loss was (85±33) ml. The postoperative ambulation time was (3.1±1.9) days, and the hospitalization time was (9.0±2.6) days. Before the operation, the average VAS (back pain) score was 5.2±1.0, the average of VAS (leg pain) score was 6.8±1.9 and ODI was 56.6%±12.8%. VAS score was reduced to 1.4±0.6 (waist pain) and 0.9±0.4 (leg pain). ODI was improved to 13.8%±6.3%. All the difference between preoperative and the last follow-up was statically significant (all P<0.01). No internal fixation failure, pseudarthrosis and adjacent re-degeneration were observed in the final follow-up. Conclusion: The application of CBTS and SAS internal fixation techniques in the surgical treatment of lumbar ASD has the advantages of less trauma, faster postoperative recovery, reliable internal fixation, and fewer complications, especially in patients with low bone mineral density.

[Analysis of common viral infection in surveillance cases of febrile respiratory syndrome in 9 provinces of China from 2009 to 2021].

Objective: To understand the common viral infection among the surveillance cases of fever respiratory syndrome (FRS) in nine provinces in China. Methods: The research data were obtained from nine provinces (Anhui, Beijing, Guangdong, Hebei, Hunan, Jilin, Shandong, Shaanxi and Xinjiang) in the "Infectious Disease Surveillance Technology Platform Information Management System" of the Chinese Center for Disease Control and Prevention from January 2009 to June 2021. Finally, 8 243 FRS cases with nucleic acid detection results of eight viruses [human influenza virus (HIFV), human respiratory syncytial virus (HRSV), human adenovirus (HAdV), human parainfluenza virus (HPIV), human rhinovirus (HRV), human metapneumovirus (HMPV), human coronavirus (HCoV) and human Boca virus (HBoV)] were included in the study. The χ2 test/Fisher exact probability method was used to analyze the difference of virus detection rate in different age groups, regions and seasons. Results The M (Q1, Q3) age of 8 243 FRS cases was 4 (1, 18) years old, and 56.56% (4 662 cases) were children under 5 years old. Males accounted for 58.1% (4 792 cases) of all cases. All cases were from outpatient/emergency department (2 043 cases) and inpatient department (6 200 cases). The virus detection rates of FRS cases from high to low were HRSV, HIFV, HPIV, HRV, HAdV, HMPV, HCoV and HBoV. Two or more viruses were detected simultaneously in 524 cases, accounting for 15.66% of virus-positive cases. The difference of the virus detection rate in different age groups was statistically significant (all P values<0.05), and the virus detection rate in children<5 years old was higher (49.96%). The positive rate of any virus in south China was higher than that in north China (P<0.001). The virus-positive FRS cases were detected throughout the year. The detection rate of HRSV was higher in autumn and winter. The detection rate of HIFV was higher in winter. The detection rate of HMPV was higher in winter and spring. The detection rates of HPIV, HRV, HCoV and HBoV were higher in summer and autumn, while there was no significant difference in the detection rate of HAdV in different seasons. Compared with 2009-2019, the detection rate of any virus in 2020-2021 decreased from 41.37% to 37.86%. The detection rate of HIFV decreased sharply from 10.62% to 1.37%. The detection rate of HPIV decreased from 8.24% to 5.88%. The detection rate of HRV and HBoV increased from 5.43% and 1.79% to 9.67% and 3.19%, respectively. Conclusion: HRSV and HIFV infections are more common among FRS cases in nine provinces in China from 2009 to 2021, and the epidemiological characteristics of eight common respiratory viruses vary in different age groups, regions and seasons.

[Clinical research progress in non-invasive positive pressure ventilation from 2020 to 2021].

Non-invasive positive pressure ventilation (NPPV), an essential respiratory support method, is widely used in acute/chronic respiratory failure and assisting rehabilitation in patients with chronic obstructive pulmonary disease (COPD). We searched the relevant research articles about NPPV published from 1st October 2020 to 30th September 2021 through Medline. Researches focusing on the clinical application and viral transmission protection during high-flow nasal cannula oxygen and NPPV in COVID-19, were mainly retrospective and of small sample size. It demonstrated that high-flow nasal cannula oxygen and NPPV might reduce intubation rates when treating patients with mild-to-moderate respiratory failure, but the risk of delayed intubation should draw particular precaution. When using NPPV in non-COVID-19-related de novo acute respiratory failure, diaphragm thickening fraction and tidal change of esophageal pressure were validated to predict the treatment outcome. In addition, some studies explored the compliance and related influencing factors associated with the treatment effects of early NPPV initiation on amyotrophic lateral sclerosis patients and the effects of NPPV on dynamic hyperinflation during exercise in COPD patients. Furthermore, the effectiveness of neurally adjusted ventilatory assist ventilation and a novel communication device optimizing the use of NPPV were also investigated and outlined.

[Efficacy of fenestrated atrial septal defect occulders on pulmonary hypertension dogs].

Objective: To explore the short-term efficacy of fenestrated atrial septal defect (ASD) occulders in the treatment of pulmonary arterial hypertension (PAH). Methods: Thirty-six healthy dogs were divided into the balloon atrial septostomy (BAS)+fenestrated ASD occulders group (n=12), BAS group (n=12) and non-septostomy group (n=12). PAH was induced by intra-atrial injection of dehydrogenized monocrotaline (1.5 mg/kg) in all dogs. Animals in the BAS+fenestrated ASD occulders group underwent atrial septal puncture and fenestrated ASD occulders implantation. Animals in the BAS group underwent balloon atrial septostomy. The non-septostomy group received no surgical intervention. The hemodynamic indexes and blood N-terminal pro-B-type natriuretic peptide (NT-proBNP) of dogs were measured before modeling, 2 months after modeling, 1, 3, and 6 months after surgery, respectively. Echocardiography was performed to observe the patency of the shunt and atrial septostomy of the dogs in the BAS+fenestrated ASD occulders group and BAS group at 1, 3, and 6 months after surgery. Three dogs were sacrificed in each group at 1, 3, and 6 months after surgery, respectively. Atrial septal tissue and fenestrated ASD occulders were removed to observe the patency and endothelialization of the device. Lung tissues were obtained for hematoxylin-eosin (HE) staining to observe the inflammatory cells infiltration and the thickening and narrowing of the pulmonary arterials. Results: Among 36 dogs, 2 dogs died within 24 hours after modeling, and 34 dogs were assigned to BAS+fenestrated ASD occulders group (n=12), BAS group (n=11), and non-septostomy group (n=11). Compared with BAS group, the average right atrial pressure (mRAP) and NT-proBNP of dogs in the BAS+fenestrated ASD occulders group were significantly reduced at 3 months after surgery (P<0.05), and the cardiac output (CO) was significantly increased at 6 months after surgery, arterial oxygen saturation (SaO2) was also significantly reduced (P<0.05). Compared with non-septostomy group, dogs in the BAS+fenestrated ASD occulders group had significantly lower mRAP and NT-proBNP at 1, 3, and 6 months after surgery (P<0.05), and higher CO and lower SaO2 at 6 months after surgery (P<0.05). Compared with the non-septostomy group, the dogs in the BAS group had significantly lower mRAP and NT-proBNP at 1 month after surgery (P<0.05), and there was no significant difference on mRAP and NT-proBNP at 3 and 6 months after surgery (P>0.05). Echocardiography showed that there was a minimal right-to-left shunt in the atrial septum in the BAS group at 1 month after the surgery, and the ostomy was closed in all the dogs in the BAS group at 3 months after the surgery. There was still a clear right-to-left shunt in the dogs of BAS+fenestrated ASD occulders group. The shunt was well formed and satisfactory endothelialization was observed at 1, 3 and 6 months after surgery. The results of HE staining showed that the pulmonary arterials were significantly thickened, stenosis and collapse occurred in the non-septostomy group. Pulmonary microvascular stenosis and inflammatory cell infiltration in the pulmonary arterials were observed in the non-septostomy group. Pulmonary arterial histological results were comparable between BAS+fenestrated ASD occulders group and non-septostomy group at 6 months after surgery. Conclusions: The fenestrated ASD occulder has the advantage of maintaining the open fistula hole for a longer time compared with simple balloon dilation. The fenestrated ASD occulder can improve cardiac function, and it is safe and feasible to treat PAH in this animal model.

Blockade of BK channels attenuates chronic visceral hypersensitivity in an IBS-like rat model.

BACKGROUND: Visceral hypersensitivity in irritable bowel syndrome (IBS) is still poorly understood, despite that chronic abdominal pain is the most common symptoms in IBS patients. To study effects of BK channels on visceral hypersensitivity in IBS rats and the underlying mechanisms, IBS rats were established by colorectal distention (CRD) in postnatal rats. The expression of large-conductance calcium and voltage-dependent potassium ion channels (BK channels) of the thoracolumbar spinal cord was examined in IBS and control rats. The effects of BK channel blockade on visceral hypersensitivity were evaluated. The interaction of BK channels and N-methyl-D-aspartate acid (NMDA) receptors was explored, and synaptic transmission at superficial dorsal horn (SDH) neurons of the thoracolumbar spinal cord was recorded by whole-cell patch clamp in IBS rats. RESULTS: The expression of the BK channels of the thoracolumbar spinal cord in IBS rats was significantly reduced. The blockade of BK channels could reduce the visceral hypersensitivity in IBS rats. There was an interaction between BK channels and NMDA receptors in the spinal cord. The frequency of spontaneous inhibitory postsynaptic currents (sIPSCs) in SDH neurons is significantly reduced in IBS rats. The blockade of BK channels depolarizes the inhibitory interneuron membrane and increases their excitability in IBS rats. CONCLUSIONS: BK channels could interact with NMDA receptors in the thoracolumbar spinal cord of rats and regulate visceral hypersensitivity in IBS rats.

Preweaning to postweaning rumen papillae structural growth, ruminal fermentation characteristics, and acute-phase proteins in calves.

This study evaluated pre- to postweaning ruminal structural development, fermentation characteristics, and acute-phase protein levels in calves with a high milk replacer (MR) feeding rate prior to weaning. Six ruminally cannulated Holstein bull calves were fed MR (150 g/L) at 15% of body weight (BW) in 2 equal volumes daily. Volumes were adjusted weekly based on BW. Calves were weaned using a 1-step weaning method, with MR decreased by 50% at the end of wk 5 and full weaning at the end of wk 6. Calf starter, chopped straw, and water were offered ad libitum. Intake was recorded daily, and BW was recorded weekly. From wk 5 to 12, ruminal pH was continuously measured using a ruminal pH bolus. Ruminal fluid was collected weekly from wk 5 to 12 for measurement of short-chain fatty acid concentrations and quantification of total bacteria and protozoa. Rumen papillae were obtained at wk 5, 6, 7, 8, and 12 for histological analysis. Serum amyloid A and lipopolysaccharide-binding protein were measured weekly. Data were analyzed using GLIMMIX procedure of SAS (SAS Institute Inc., Cary, NC), with week as a fixed effect and calf as a random effect. During the weaning step-down, starter intake was 3-fold higher and continued to increase until wk 12. Body weight increased from birth to wk 12; however, BW did not change during wk 6, 7, and 8, possibly due to low metabolizable energy intake caused by the weaning strategy. Preweaning ruminal pH was below 5.8 for approximately 936.3 ± 125.99 min/d, implying ruminal acidosis. Furthermore, ruminal pH below 5.8 reached a peak at wk 8 with 1,203.9 ± 227.65 min/d below pH 5.8 and slowly decreased to 388.1 ± 189.82 min/d below pH 5.8 at wk 12. Papillae surface area, length, and width increased during wk 12 compared with wk 5. Corneum thickness increased by week, whereas spinosum/basale thickness only increased during wk 8 compared with wk 5. The acute-phase protein concentration was highest at wk 1 and then decreased and remained constant until wk 12. In conclusion, even before step-down weaning, calves experienced ruminal acidosis despite low starter intake. Further, the observed prolonged ruminal pH depression suggests that dietary rumen adaptation after weaning can take several weeks in calves with a high MR feeding rate preweaning. The prolonged depressed ruminal pH did not affect acute-phase proteins and this finding, along with the other results, suggests that rumen epithelium barrier integrity is not compromised during weaning.

Longitudinal assessment revealed the shifts in rumen and colon mucosal-attached microbiota of dairy calves during weaning transition.

The objectives of this study were to investigate the shifts in rumen and colon mucosa-associated microbiota in dairy calves fed a high milk replacer feeding rate before and after weaning and to determine whether such shifts are associated with tissue physiological measures. Longitudinal biopsy was performed to collect rumen and colon mucosal tissues of 4 ruminally cannulated Holstein dairy bull calves (weaned at 6 wk of age) at the end of wk 5 (before weaning), 7 (weaning adaptation) and 12 (after weaning), and were used to assess mucosa-associated microbiota and their changes using amplicon sequencing. Both rumen and colon mucosa-associated bacterial communities shifted during the weaning process, as evidenced by their clear separation among 3 different weaning periods and increased α diversity (Shannon and Chao1 indices) during weaning transition. Among the 3 dominant bacterial phyla identified (relative abundance >1.0%), the relative abundance of Proteobacteria and Bacteroidetes decreased in the rumen mucosa, whereas the relative abundance of Firmicutes increased in both rumen and colon mucosa during weaning transition. In the rumen mucosa, Campylobacter (0.6-22.1%) gradually became prevalent during weaning transition, whereas Succinivibrio (6.2-10.3%) and Prevotella 1 (4.7-10.5%) were dominant regardless of weaning transition. In the colon mucosa, Bacteroides (12.8-25.4%) was dominant during weaning transition, although its relative abundance decreased after weaning. In the meantime, relative abundance of uncultured Lachnospiraceae increased from 2.2% to 25.7% during this period. In addition, genera Pyramidobacter (in the rumen mucosa) and Lachnoclostridium (in the colon mucosa) were positively correlated with rumen papilla surface area and colon mucosal thickness, respectively. Moreover, genera Ruminococcaceae UCG-005 and Sharpea in the rumen mucosa were positively correlated with the molar proportion of propionate and butyrate, respectively. Overall, our findings revealed that rumen and colon mucosa-associated bacterial communities altered in response to the weaning transition, and some bacterial taxa in these communities may have positive effects on rumen and colon mucosa development during this period.