[Research on the framework of biosafety standards for pathogenic microbial laboratories]

Developing and implementing biosafety standards for pathogenic microbiology laboratories is essential to achieving scientific, efficient, and standardized management and operation. This article analyzes the current standardization construction in biosafety in pathogenic microbiology laboratories domestically and internationally. It proposes a framework for the biosafety standard system of pathogenic microbiology laboratories, which mainly includes four parts: basic standards, management standards, technical standards, and industry applications. It provides a reference for the standardization work of pathogenic microbiology laboratories and helps to standardize the biosafety industry in China.

[Association between anti-tissue transglutaminase antibody titers and duodenal histopathology among adults with celiac disease]

To evaluate the association between serum anti-tissue transglutaminase antibody (anti-tTG) titers and the severity of histological damage to the duodenal mucosa and to predict a possible anti-tTG cutoff value for diagnosing celiac disease (CD) and villous atrophy in the domestic population. Clinical and pathological data from 76 adult CD patients with positive anti-tTG titers and duodenal biopsy results who were treated at the People's Hospital of Xinjiang Uygur Autonomous Region from July 2017 to January 2022 were retrospectively analyzed. The correlation between anti-tTG titers and the severity of duodenal mucosal damage was statistically assessed to predict the optimal anti-tTG titer cut-off value for diagnosing CD and villous atrophy. Of the 76 patients, 10 had underlying CD, and of the 66 patients with duodenal histopathology, four were Marsh Ⅰ, six were Marsh Ⅱ, and 56 were Marsh Ⅲa-c grade. In adults with CD, anti-tTG titers were shown to be associated with the severity of histological damage to the duodenal mucosa. When the anti-tTG level was ≥5 times the upper limit of normal (ULN), the sensitivity and specificity for diagnosing CD were 83.9% and 92.9%, respectively. When the anti-tTG titer was ≥8 times the ULN, the sensitivity and specificity for diagnosing villous atrophy were 67.9% and 90.0%, respectively. Anti-tTG levels had a strong predictive value for diagnosing CD in adults when titers exceeded 10 times the ULN. Thus, the anti-tTG cut-off value can be combined with clinical judgment to diagnose CD, limiting the use of invasive endoscopy.

[Establishment and application of a clustered management plan for pulmonary care of massive burn casualties]

Objective: To establish a clustered management plan for pulmonary care of massive burn casualties (hereinafter referred to as the clustered management plan for pulmonary care), and to explore its application effects. Methods: (1) A clustered care intervention group was established, including the medical and nursing staff from the Department of Burns and Plastic Surgery, Department of Respiratory Medicine, and Department of Infection Control at the Fourth Medical Center of PLA General Hospital (hereinafter referred to as our hospital). Four major links, including pulmonary care assessment, chest and lung physical therapy, artificial airway management, and specialized infection control were sorted out according to the key points and difficulties in pulmonary care for massive burn casualties. Evidence-based nursing methods were employed to retrieve articles related to the above-mentioned four links from PubMed, Chinese Journal Full-Text Database, VIP Database and Wanfang Data using terms of " mass burn, respiratory management and airway management" and terms of ",," , and the clustered management plan for pulmonary care was established based on reading and discussion in combination with clinical practice and experience. (2) In this non-randomized controlled study, the clustered management plan for pulmonary care was applied to 73 massive burn patients (48 males and 25 females, aged 32 (25, 38) years) who were admitted to our hospital from January 2016 to December 2019 and met the inclusion criteria, and they were included into the clustered care group; 43 massive burn patients (25 males and 18 females, aged 35 (17, 45) years) who were admitted to our hospital from January 2013 to December 2015, received routine care and met the inclusion criteria were retrospectively included into routine care group. The pulmonary infection rate and mortality of patients in the two groups were recorded during the hospital stay. Data were statistically analyzed with chi-square test, Mann-Whitney U test, and independent sample t test. Results: (1) The clustered management plan for pulmonary care included a total of 12 specific measures covering four aspects of pulmonary care. The contents in pulmonary care assessment clearly stated to include the previous medical history, history of injury, respiratory status, hoarseness, pulmonary auscultation, etc. Chest and lung physical therapy included how to guide patients to effectively cough and do pursed lip breathing and abdominal breathing exercise, etc. Artificial airway management specified the preparation for the establishment of artificial airway at clinical reception, the observation index and frequency after tracheotomy, the method of humidification, the method and frequency of sputum suction, and the management of mechanical ventilation, etc. Specialized infection control required to strengthen hand hygiene and ventilator management. (2) The pulmonary infection rate and mortality of patients in the clustered care group were 2.74% (2/73) and 4.11% (3/73), respectively, significantly lower than 25.58% (11/43) and 18.60% (8/43) in routine care group (χ(2)=11.986, 5.043, P<0.05 or P<0.01). Conclusions: The clustered management plan for pulmonary care developed for massive burn casualties focuses on the major links and key points. The measures are systemic and comprehensive, simple but precise, and highly operable, covering the entire process of massive burn care, hereby reducing the pulmonary infection rate significantly and improving the success rate of treatment.

Tuning interfacial Dzyaloshinskii-Moriya interactions in thin amorphous ferrimagnetic alloys

Skyrmions can be stabilized in magnetic systems with broken inversion symmetry and chiral interactions, such as Dzyaloshinskii-Moriya interactions (DMI). Further, compensation of magnetic moments in ferrimagnetic materials can significantly reduce magnetic dipolar interactions, which tend to favor large skyrmions. Tuning DMI is essential to control skyrmion properties, with symmetry breaking at interfaces offering the greatest flexibility. However, in contrast to the ferromagnet case, few studies have investigated interfacial DMI in ferrimagnets. Here we present a systematic study of DMI in ferrimagnetic CoGd films by Brillouin light scattering. We demonstrate the ability to control DMI by the CoGd cap layer composition, the stack symmetry and the ferrimagnetic layer thickness. The DMI thickness dependence confirms its interfacial nature. In addition, magnetic force microscopy reveals the ability to tune DMI in a range that stabilizes sub-100 nm skyrmions at room temperature in zero field. Our work opens new paths for controlling interfacial DMI in ferrimagnets to nucleate and manipulate skyrmions.

Development of a magnetic bead-based method for the collection of circulating extracellular vesicles

Cells release different types of extracellular vesicles (EVs). These EVs contain biomolecules, including proteins and nucleic acids, from their parent cells, which can be useful for diagnostic applications. The aim of this study was to develop a convenient procedure to collect circulating EVs with detectable mRNA or other biomolecules. Magnetic beads coated with annexin A5 (ANX-beads), which bound to phosphatidylserine moieties on the surfaces of most EVs, were tested for their ability to capture induced apoptotic bodies in vitro and other phosphatidylserine-presenting vesicles in body fluids. Our results show that up to 60% of induced apoptotic bodies could be captured by the ANX-beads. The vesicles captured from cultured media or plasma contained amplifiable RNA. Suitable blood samples for EV collection included EDTA-plasma and serum but not heparin-plasma. In addition, EVs in plasma were labile to freeze-and-thaw cycles. In rodents xenografted with human cancer cells, tumor-derived mRNA could be detected in EVs captured from serum samples. Active proteins could be detected in EVs captured from ascites but not from plasma. In conclusion, we have developed a magnetic bead-based procedure for the collection of EVs from body fluids and proved that captured EVs contain biomolecules from their parent cells, and therefore have great potential for disease diagnosis.

Detection of reactive oxygen species during the cell cycle under normal culture conditions using a modified fixed-sample staining method

We developed an alternative method of simultaneously monitoring the generation of reactive oxygen species (ROS) and cellular oxidative responses using the oxidation-sensitive fluorescent probe dichlorofluorescein (DCF) in fixed samples. In this study, we evaluated the ability of this method to detect ROS generation during the cell cycle under normal culture conditions using flow cytometric analyses. Among the fixatives tested, only acetone and paraformaldehyde did not alter the endogenous oxidation of the responsive dye 5-(and-6)-chloromethyl-2',7'-dichlorodihydrofluorescein diacetate (CM-H2DCFDA), which is a chloromethyl derivative of H2DCFDA. Only acetone fixation followed by staining with propidium iodide was able to detect ROS generation during the cell cycle without altering DCF oxidation. Further thymidine treatment led to cell cycle arrest at the G1 phase followed by the downregulation of total intracellular ROS. Paraformaldehyde-based fixation enabled the evaluation of ROS generation by immunostaining at a different phase of the cell cycle, whereas MPM2 co-staining enabled identification of the specific mitotic phase. This study demonstrates a modified fixed-sample method that can be used to measure intracellular ROS production during the cell cycle using standard immunostaining techniques.

Blockade of reactive oxygen species and Akt activation is critical for anti-inflammation and growth inhibition of metformin in phosphatase and tensin homolog-deficient RAW264.7 cells

CONTEXT

Metformin is widely used for treatment of type 2 diabetes and has a potential application on the treatment of inflammation and cancer. Phosphatase and tensin homolog (PTEN) plays a critical role in cancer cell growth and inflammation; however, precise mechanisms remain unclear.

OBJECTIVE

We aimed to investigate the possible mechanisms of how PTEN regulates metformin against cell growth and inflammation.

MATERIALS AND METHODS

We established PTEN knockdown in RAW264.7 murine macrophages (shPTEN cells) to detect inflammatory mediators using commercial kits, production of reactive oxygen species (ROS) by flow cytometry, cell growth by MTT assay and phosphorylated levels of signal molecules by western blot.

RESULTS

The shPTEN cells had a significant large amount of inflammatory mediators, such as inducible nitric oxide synthase (iNOS)/nitric oxide (NO) and cyclooxygenase-2 (COX-2)/prostaglandin E(2) (PGE(2)); and also elevated the production of ROS and increased cell proliferation. These effects were accompanied with the activation of Akt and p38 mitogen-activated protein kinase (MAPK), and the inactivation of an AMP-activated protein kinase (AMPK) activator and extracellular signal-regulated kinase 1/2. Pretreatment with metformin not only blocked these inflammatory mediators, but also caused growth inhibition induced by significant apoptosis. Furthermore, inactivation of Akt, blockade of ROS generation and independence of activations of AMPK and MAPK by metformin were also observed.

CONCLUSION

Macrophages with PTEN deficiency developed a continuous inflammatory microenvironment, which further aggravated tumor cell growth. Moreover, metformin affected PTEN-deficient cells dependent of inhibition of ROS production and Akt activation against enlarged inflammatory mediators and/or cell growth in shPTEN cells.

Glycogen synthase kinase-3β regulates anti-inflammatory property of fluoxetine

A selective serotonin reuptake inhibitor fluoxetine not only is widely used in the treatment of depression but also has an anti-inflammatory property. Glycogen synthase kinase-3beta (GSK-3β) is a vital factor in the inflammation process. How fluoxetine interferes with inflammation via a GSK-3β-dependent pathway remains unclear. The aim of this study is to investigate the effects of fluoxetine on lipopolysaccharide (LPS)-induced inflammation. Results showed that fluoxetine decreased mortality rate of the mice. It also inhibited LPS-induced release of nitric oxide (NO) and prostaglandin E2 (PGE2) in serum and RAW264.7 murine macrophages and expressions of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Upon LPS stimulation, fluoxetine caused a delay but increased in the phosphorylated levels of GSK-3β (ser9), whereas it did not affect LPS-induced activation of mitogen-activated protein kinase (MAPK) and generation of reactive oxygen species (ROS). Fluoxetine in combination with phosphatidylinositol 3-kinases/Akt inhibitors (LY294002 and Wortmannin) did not have a synergistic inhibition on LPS-induced NO release and PGE2 production. In addition, peroxisome proliferator-activated receptor γ (PPARγ) antagonist GW9622 showed no reverse effects of this inhibition of fluoxetine. GSK-3β knockdown blocked the inhibitory effects of fluoxetine on LPS-induced iNOS/NO release and COX-2/PGE2 production. These results indicated that GSK-3β regulated anti-inflammatory property of fluoxetine. However, Akt activation, ROS generation, and altered PPARγ activity were not involved in this inhibition of fluoxetine.

Dermatophagoides pteronyssinus 2 regulates nerve growth factor release to induce airway inflammation via a reactive oxygen species-dependent pathway

Group 2 allergen of Dermatophagoides pteronyssinus 2 (Der p2) induces airway inflammation without protease activity, and elevated nerve growth factor (NGF) levels are also found in this inflammation. How the allergen Der p2 regulates NGF release via reactive oxygen species (ROS) to induce inflammation remains unclear. In the present study, intratracheal administration of Der p2 to mice led to inflammatory cell infiltration, mucus gland hyperplasia, and NGF upregulation in the bronchial epithelium, as well as elevated ROS and NGF production in bronchoalveolar lavage fluids. In addition, Der p2 caused fibrocyte accumulation and mild fibrosis. p38 mitogen-activated protein kinase (MAPK) and c-Jun N-terminal kinase (JNK) inhibitors inhibited Der p2-induced NGF release in LA4 lung epithelial cells and MLg lung fibroblasts. Pretreatment with an antioxidant, tiron, reduced the Der p2-induced ROS production, NGF expression and release, p38 MAPK or JNK phosphorylation, and airway inflammation. These results suggest that Der p2 allergen-induced airway inflammation and elevated NGF release were through increasing ROS production and a MAPK-dependent pathway. The use of an antioxidant, tiron, may provide a new therapeutic modality for the treatment of allergic asthma.

[Effects of hypoxia on proliferation of pulmonary arterial smooth muscle cells]

AIM

To investigate the effects of hypoxia on the proliferation of different diameter intra-pulmonary artery smooth muscle cells (PASMCs), and to study the possible signal transduction pathway in proliferation caused by hypoxia.

METHODS

PASMCs were isolated from three different size of pulmonary arteries (>1 000 microm, 500-800 microm, 300-400 microm diameter) and cultured separately. 3H-TdR incorporation and cell number were used to measure cell proliferation.

RESULTS

3H-TdR incorporation and cell number of PASMCs from three sizes of pulmonary artery (> 1 000 microm, 500-800 microm, 800-400 microm diameter) increased 23.5% and 11.1%, 60.0% and 33.8%, 141.4% and 52.0%, respectively. Calcium antagonist (verapamil), PKC inhibitor (staurosporine), and Na(+)-H+ exchange inhibitor (amiloride) were used in PASMCs isolated from 300-400 microm diameter pulmonary artery. The results showed that verapamil, staurosporine and amiloride could notably block hypoxia-induced increase 3H-TdR incorporation and cell number.

CONCLUSION

Proliferation of pulmonary artery smooth muscle cell responded to hypoxia differently according to the artery size; activation of calcium channel, PKC and Na(+)-H+ exchange might mediate the proliferation initiated by hypoxia.

Effects of angiotensin-converting enzyme and angiotensin II on hypoxia-induced proliferation of cultured intra-pulmonary artery smooth muscle cells

AIM

To investigate whether local angiotensin-converting enzyme (ACE) and endogenous angiotensin II (ANG II) are involved directly in the proliferation of intra-pulmonary artery smooth muscle cells (PASMC) induced by hypoxia.

METHODS

Smooth muscle cells isolated from rabbit intra-pulmonary artery (300-400 microns-diameter) were cultured and used in the 3-8 passages. [3H]Thymidine incorporation and cell counts were used to measure PASMC proliferation.

RESULTS

Exposure of PASMC to hypoxia for 24 h resulted in an increase in the [3H]thymidine incorporation and cell number by 166.6% and 52.0% as compared with normoxia (P < 0.01). Treatment with either captopril or losartan markedly inhibited the increase, compared with the control, [3H]thymidine incorporation was inhibited by 51.3% (P < 0.01) and 49.8% (P < 0.01) and cell number was inhibited by 22.2% (P < 0.01) and 17.9% (P < 0.01), respectively, while PD-123319 showed no significant effect.

CONCLUSION

Local overexpression of PASMC ACE and ANG II play an important role in the proliferation of PASMC induced by hypoxia.

[Effect of hypoxia on angiotensin-converting enzyme activity and gene expression of intrapulmonary artery smooth muscle cells]

In order to observe the effect of hypoxia on pulmonary artery smooth muscle cells (PASMC), angiotensin-converting enzyme (ACE) activity was measured by colometry and the expression of ACE mRNA was detected by Northern blot, using rabbit isolated and cultured PASMC. The main results are as follows: (1) under normoxia both ACE activity and gene expression could be detected in PASMC; and (2) the expression level of ACE mRNA, after an initial latent period of 6 h hypoxia, began to show a marked increase with time in the next 12, 24 and 48 h. Exposure to hypoxia for 24 h resulted in an increase in either culture medium or cell ACE activity, as compared with that under normoxia. The results suggest that PASMC ACE increased by hypoxia might play an important role in the development of hypoxic pulmonary hypertension.

[Effects of hypoxia and anisodamine on products of TXA2 and PGI2 in cultured intra-pulmonary arteriolar smooth muscle cells]

The changes of contents of TXB2 and 6-Keto-PGF1a were studied in severely acute hypoxic cultured intra-pulmonary arteriolar smooth muscle cells (PASMCs) under the action of anisodamine. The results demonstrated that the contents of TXB2 and 6-Keto-PGF1a and their ratio were significantly increased in severe acute hypoxic PASMCs' medium. The content of TXB2 decreased significantly, but the content of 6-Keto-PGF1a was hardly affected by anisodamine under normoxia and hypoxia. These findings suggest that acute and severe hypoxia results in pulmonary vascular constriction through increased production of PASMCs and liberation of TXA2, or PGI2, and increased TXA2/PGI2 ratio. The latter effect of hypoxia could be prevented by anisodamine, which antagonized the effect of hypoxia induced pulmonary vasoconstriction.

[Effect of platelet activating factor on TxA2, PGI2 and Ca(2+)-ATPase activity in the intra-pulmonary artery smooth muscle cells]

The effects of exogenous platelet activating factor (PAF), BN52021 (an antagonist of PAF receptor), indomethacin and verapamil on the production of TxA2, PGI2 and activity of Ca(2+)-ATPase were investigated in rabbit intra-pulmonary smooth muscle cells (PASMCs). The results were as follows: (1) Under basic condition, active AA metablism was present in PASMCs. (2) Significant increase of TxA2 and PGI2 but not their ratio may result from binding of PAF receptor and activation of cyclooxgenase. (3) Activity of Ca(2+)-ATPase could be inhibited by exogenous PAF. (4) The inhibitory effect of PAF on PASMCs Ca(2+)-ATPase could be reversed by verapamil.

[Variation of plasma platelet activating factor during development and reversal of hypoxic pulmonary hypertension in conscious sheep]

A model of hypoxic pulmonary hypertension was made in conscious sheep, and plasma platelet activating factor (PAF) were measured by radioimmunoassay method during the beginning, progression and reversal of hypoxic pulmonary hypertension. The main results were as follows: (1) Under hypoxic condition for 4 days, the conscious sheep develops hypoxemia and marked hypoxic pulmonary vasoconstriction (HPV). These response were reversible. (2) At the beginning of hypoxia, plasma PAF increased, but did not continually increase with hypoxic prolongation and development of HPV. (3) Upon cessation of hypoxia with reversal of pulmonary hypertension, plasma PAF did not show any parallel decrease. These results indicate that plasma PAF is in no way involves in the development of HPV in conscious sheep.

Optical heteroassociative memory using spatial light rebroadcasters

A new device, a spatial light rebroadcaster, is described that can have optical disk resolution and high speed. Experimental results demonstrate resolution, speed, linearity, logic operation, and arithmetic computation. The device is suitable for optical computing, in particular for memory systems. Optical masking for controlling memory recall and 100 x 100 matrix-vector multiplication are demonstrated. A one pass optical heteroassociative memory system was assembled that uses an optical outer product formulation to store associated 32-bit vectors. Recall is achieved by optical matrix-vector multiplication. The results show the suitability of these devices for memory systems in optical computers.