A novel class of xylanases specifically degrade marine red algal ß1,3/1,4-mixed-linkage xylan.

Xylans are polysaccharides composed of xylose and include ß1,4-xylan, ß1,3-xylan, and ß1,3/1,4-mixed-linkage xylan (MLX). MLX is widely present in marine red algae and constitutes a significant organic carbon in the ocean. Xylanases are hydrolase enzymes that play an important role in xylan degradation. While a variety of ß1,4-xylanases and ß1,3-xylanases involved in the degradation of ß1,4-xylan and ß1,3-xylan have been reported, no specific enzyme has yet been identified that degrades MLX. Herein, we report the characterization of a new MLX-specific xylanase from the marine bacterium Polaribacter sp. Q13 which utilizes MLX for growth. The bacterium secretes xylanases to degrade MLX, among which is Xyn26A, an MLX-specific xylanase that shows low sequence similarities (<27%) to ß1,3-xylanases in the glycoside hydrolase family 26 (GH26). We show that Xyn26A attacks MLX precisely at ß1,4-linkages, following a ß1,3-linkage toward the reducing end. We confirm that Xyn26A and its homologs have the same specificity and mode of action on MLX, and thus represent a new xylanase group which we term as MLXases. We further solved the structure of a representative MLXase, AlXyn26A. Structural and biochemical analyses revealed that the specificity of MLXases depends critically on a precisely positioned ß1,3-linkage at the -2/-1 subsite. Compared to the GH26 ß1,3-xylanases, we found MLXases have evolved a tunnel-shaped cavity that is fine-tuned to specifically recognize and hydrolyze MLX. Overall, this study offers a foremost insight into MLXases, shedding light on the biochemical mechanism of bacterial degradation of MLX.

A Bifunctional Wearable Sensor Based on a Nanoporous Membrane for Simultaneous Detection of Sweat Lactate and Temperature.

Wearable sensors for non-invasive, real-time detection of sweat lactate have far-reaching implications in the fields of health care and exercise physiological responses. Here, we propose a wearable electrochemical sensor with gold nanoelectrode arrays fabricated on the nanoporous polycarbonate (PC) membrane by encapsulating lactate oxidase (LOx) in chitosan (CS) hydrogel for detecting body temperature and sweat lactate concurrently. Flexible gold nanoporous electrodes not only enhance electrode area but also offer a nanoconfined space to accelerate the catalytic reaction of LOx and control substrate concentration on the surface of LOx to decrease substrate inhibition. The proposed sensor has a long durability of 13 days and better selectivity for the detection of sweat lactate over a wide linear range (0.01-35 mM) with a low detection limit (0.144 µM). Furthermore, temperature-dependent transmembrane currents passing through the sensor are used to estimate body temperature. We then use multiple linear regression to adjust the effect of temperature on lactate detection and succeed in monitoring lactate molecules in sweat and body temperature during exercise.

The catabolic specialization of the marine bacterium Polaribacter sp. Q13 to red algal ß1,3/1,4-mixed-linkage xylan.

Catabolism of algal polysaccharides by marine bacteria is a significant process of marine carbon cycling. ß1,3/1,4-Mixed-linkage xylan (MLX) is a class of xylan in the ocean, widely present in the cell walls of red algae. However, the catabolic mechanism of MLX by marine bacteria remains elusive. Recently, we found that a marine Bacteroidetes strain, Polaribacter sp. Q13, is a specialist in degrading MLX, which secretes a novel MLX-specific xylanase. Here, the catabolic specialization of strain Q13 to MLX was studied by multiomics and biochemical analyses. Strain Q13 catabolizes MLX with a canonical starch utilization system (Sus), which is encoded by a single xylan utilization locus, XUL-Q13. In this system, the cell surface glycan-binding protein SGBP-B captures MLX specifically, contributing to the catabolic specificity. The xylanolytic enzyme system of strain Q13 is unique, and the enzymatic cascade dedicates the stepwise hydrolysis of the ß1,3- and ß1,4-linkages in MLX in the extracellular, periplasmic, and cytoplasmic spaces. Bioinformatics analysis and growth observation suggest that other marine Bacteroidetes strains harboring homologous MLX utilization loci also preferentially utilize MLX. These results reveal the catabolic specialization of MLX degradation by marine Bacteroidetes, leading to a better understanding of the degradation and recycling of MLX driven by marine bacteria.IMPORTANCERed algae contribute substantially to the primary production in marine ecosystems. The catabolism of red algal polysaccharides by marine bacteria is important for marine carbon cycling. Mixed-linkage ß1,3/1,4-xylan (MLX, distinct from hetero-ß1,4-xylans from terrestrial plants) is an abundant red algal polysaccharide, whose mechanism of catabolism by marine bacteria, however, remains largely unknown. This study reveals the catabolism of MLX by marine Bacteroidetes, promoting our understanding of the degradation and utilization of algal polysaccharides by marine bacteria. This study also sets a foundation for the biomass conversion of MLX.

Diagnostic value of serum NLRP3, metalloproteinase-9 and interferon-γ for postoperative hydrocephalus and intracranial infection in patients with severe craniocerebral trauma.

Traumatic brain injury (TBI) is a major cause of morbidity and mortality globally. We unveiled the diagnostic value of serum NLRP3, metalloproteinase-9 (MMP-9) and interferon-γ (IFN-γ) levels in post-craniotomy intracranial infections and hydrocephalus in patients with severe craniocerebral trauma to investigate the high risk factors for these in patients with TBI, and the serological factors predicting prognosis, which had a certain clinical predictive value. Study subjects underwent bone flap resection surgery and were categorized into the intracranial infection/hydrocephalus/control (without postoperative hydrocephalus or intracranial infection) groups, with their clinical data documented. Serum levels of NLRP3, MMP-9 and IFN-γ were determined using ELISA kits, with their diagnostic efficacy on intracranial infections and hydrocephalus evaluated by receiver operating characteristic curve analysis. The independent risk factors affecting postoperative intracranial infections and hydrocephalus were analysed by logistic multifactorial regression. The remission after postoperative symptomatic treatment was counted. The intracranial infection/control groups had significant differences in Glasgow Coma Scale (GCS) scores, opened injury, surgical time and cerebrospinal fluid leakage, whereas the hydrocephalus and control groups had marked differences in GCS scores, cerebrospinal fluid leakage and subdural effusion. Serum NLRP3, MMP-9 and IFN-γ levels were elevated in patients with post-craniotomy intracranial infections/hydrocephalus. The area under the curve values of independent serum NLRP3, MMP-9, IFN-γ and their combination for diagnosing postoperative intracranial infection were 0.822, 0.722, 0.734 and 0.925, respectively, and for diagnosing hydrocephalus were 0.865, 0.828, 0.782 and 0.957, respectively. Serum NLRP3, MMP-9 and IFN-γ levels and serum NLRP3 and MMP-9 levels were independent risk factors influencing postoperative intracranial infection and postoperative hydrocephalus, respectively. Patients with hydrocephalus had a high remission rate after postoperative symptomatic treatment. Serum NLRP3, MMP-9 and IFN-γ levels had high diagnostic efficacy in patients with postoperative intracranial infection and hydrocephalus, among which serum NLRP3 level played a major role.

CS/PVP Hydrogel-Based Nanocapillary for Monitoring Bacterial Growth and Rapid Antibiotic Susceptibility Testing.

Infection with drug-resistant bacteria poses a significant threat to human health. Judicious use of antibiotics could reduce the likelihood of bacterial resistance, which can be evaluated through antibiotic susceptibility testing (AST). This paper focuses on the application of a needle-like nanocapillary tip filled with chitosan (CS)/polyethylene pyrrolidone (PVP) hydrogel based on its specific pH-sensitive properties. The gel-filled nanocapillary has the potential to be used for electrical pH detection with a sensitivity of 3.06 nA/pH and a linear range from 7.3 to 4.3. Such sensitivity for pH measurement could be extended for monitoring of bacterial (such as Escherichia coli and Streptococcus salivarius) growth because of the relationship between pH and bacterial growth. Bacterial growth curves obtained using the hydrogel-filled nanocapillary showed good agreement with the OD600 method. Moreover, this device could be applied for rapid AST for tetracycline and norfloxacin on E. coli with minimum inhibitory concentrations of 2 and 0.125 µg/mL, respectively. This study expands the application of the hydrogel-based nanocapillary for bacterial research by monitoring changes in pH values.

Sensitive electrochemical flow injection analysis of H2O2 released from cells with a pass-through mode.

Conventional plate electrodes were commonly used in electrochemical flow injection analysis and only part of molecules diffused to the plane of electrodes could be detected, which would limit the performance of electrochemical detection. In this study, a low-cost native stainless steel wire mesh (SSWM) electrode was integrated into a 3D-printed device for electrochemical flow injection analysis with a pass-through mode, which is different compared with previous flow-through mode. This strategy was applied for sensitive analysis of hydrogen peroxide (H2O2) released from cells. Under the optimal conditions (the applied potentials, the flow rate and the sample volume), the device exhibits high sensitivity toward H2O2. Linear relationships could be achieved between electrochemical responses and the concentration of H2O2 ranging from 1 nM to 1 mM. The excellent analytical performance of the SSWM-based device could be attributed to the pass-through mode based on the mesh microstructure and intrinsic catalytic properties for H2O2 by stainless steel. This approach could be further successfully extended for screening of H2O2 released from HeLa cells with electrochemical responses linear to the number of cells in a range of 3 - 1.35 × 104 cells with an injection volume of 30 µL. This study revealed the potential of mesh electrodes in electrochemical flow injection analysis for cellular function and pathology and its possible extension in cell counting and on-line analysis.

Analysis of the split insemination (IVF+ICSI) treatment in patients with borderline semen in first cycle.

PURPOSE: The aim of this study was to verify the effectiveness of the split insemination (IVF+ICSI) in patients with borderline semen for the first cycle, we furthermore compared the treatment outcome of the conventional IVF and ICSI on sibling oocytes with the rate of blastocyst formation in different days (day 5 or day 6) as primary outcome and pregnancy as secondary outcome to provide theoretical support for embryo selection. METHODS: Between January 2017 and November 2021,190 couples undergoing the split insemination (IVF+ICSI) cycle were enrolled in the study with at least eight oocytes and the borderline semen in first cycle to analyze the basic characteristics and clinical outcome. The remaining 157 patients were analyzed in this study to compare the IVF and ICSI after excluding those who were completely unfertilized by IVF (n=33) including a patient who was completely unfertilized by IVF and ICSI. RESULTS: Present study showed that about 32(32/190,16.8%) patients with borderline semen in first cycle were completely unfertilized performing the conventional IVF and only 1(1/190,0.53%) patient was completely unfertilized using the IVF and ICSI in the split insemination (IVF+ICSI), the rate of total fertilization failure (TFF) was significantly decrease by the ICSI treatment (16.8%&0.53%,P<0.0001). By the split oocytes, the fertilization rate was significantly superior in ICSI(729/982,74.2%) compared to IVF (486/940, 51.7%, P<0.0001), the usable blastocyst and high-quality blastocyst rate on the fifth day were statistically superior in IVF compared to ICSI(31.3% &22.8%,P=0.009) (27.3%&20.6%,P=0.03), The pregnancy rate, implantation rate and live birth rate in the IVF first cycle were higher than the ICSI(75.9%&64%, respectively) (52.3%&41.8%, respectively)(64.8%&54.7%, respectively),although there was no statistical difference,it is also about ten percentage points difference. CONCLUSIONS: The treatment of sibling oocyte with both IVF and ICSI could be an appropriate choice to prevent TFF and preserve the embryo development potential for the patients with the borderline semen in present study. Furthermore, the embryo development potential from conventional IVF was better than the embryo from the ICSI technology, the ICSI technology may have a negative effect on the embryo development.

Gilvimarinus xylanilyticus sp. nov., a novel 1,3-xylanase-secreting bacterium isolated from a marine green alga.

1,3-xylan, an important organic carbon in the ocean, is peculiar to marine algae. 1,3-xylanase-secreting bacteria and their extracellular 1,3-xylanases play pivotal roles in the degradation and biomass conversion of 1,3-xylan. However, only a few 1,3-xylanase-secreting bacteria and 1,3-xylanases have been reported. Here, we identified a novel marine bacterium capable of secreting 1,3-xylanases, designated as strain HB14T. Phylogenetic analysis revealed that strain HB14T clustered tightly with known species of the genus Gilvimarinus, showing the highest 16S rRNA gene sequence similarity (97.7%) with the type strain of Gilvimarinus chinensis. Based on phylogenetic, genomic, chemotaxonomic and phenotypic studies, strain HB14T was classified as a representative of a novel species in the genus Gilvimarinus, for which the name Gilvimarinus xylanilyticus sp. nov. was proposed. The type strain is HB14T (=CCTCC AB 2022109T = KCTC 92379T). Four 1,3-xylanases secreted by strain HB14T were identified based on genome and secretome analyses, and the two (Xyn65 and Xyn80) with relatively higher abundance in secretome were successfully expressed in Escherichia coli and biochemically characterized. They showed the highest activity at pH 6.0-7.0 and 40°C and released mainly 1,3-xylobiose and 1,3-xylotriose from 1,3-xylan. These data suggest that strain HB14T acts as a player in marine 1,3-xylan degradation and recycling and that its extracellular 1,3-xylanases may have a good potential in 1,3-xylooligosaccharides preparation.

[Expression of annexin A7 in spermatogonial stem cells].

OBJECTIVE: To study the expression of Annexin A7 in the mouse testis, especially in different types of spermatogonia. METHODS: We prepared Annexin A7 recombinant protein using prokaryotic expression, adsorbed the Annexin A7 antibody with it after identified by mass spectrometry, and detected the expression of Annexin A7 by Western-blot and immunohistochemistry. RESULTS: Annexin A7 was expressed in a development-dependent manner in the spermatogonia of the prepubertal mice and in the type-A single (As) and type-A paired (Apr) spermatogonia of adult mice. These results were confirmed by the co-localization of Annexin A7 and Stra8, a known determinant of differentiated spermatogonial stem cells (SSCs). CONCLUSION: Annexin A7 is the internal factor of As and Apr spermatogonia, which might be involved in the biological functions of SSCs.

Diversity of Marine 1,3-Xylan-Utilizing Bacteria and Characters of Their Extracellular 1,3-Xylanases.

1,3-xylan is present in the cell walls of some red and green algae and is an important organic carbon in the ocean. However, information on its bacterial degradation is quite limited. Here, after enrichment with 1,3-xylan, the diversity of bacteria recovered from marine algae collected in Hainan, China, was analyzed with both the 16S rRNA gene amplicon sequencing and the culture-dependent method. Bacteria recovered were affiliated with more than 19 families mainly in phyla Proteobacteria and Bacteroidetes, suggesting a high bacterial diversity. Moreover, 12 strains with high 1,3-xylanase-secreting ability from genera Vibrio, Neiella, Alteromonas, and Gilvimarinus were isolated from the enrichment culture. The extracellular 1,3-xylanases secreted by Vibrio sp. EA2, Neiella sp. GA3, Alteromonas sp. CA13-2, and Gilvimarinus sp. HA3-2, which were taken as representatives due to their efficient utilization of 1,3-xylan for growth, were further characterized. The extracellular 1,3-xylanases secreted by these strains showed the highest activity at pH 6.0-7.0 and 30-40°C in 0-0.5M NaCl, exhibiting thermo-unstable and alkali-resistant characters. Their degradation products on 1,3-xylan were mainly 1,3-xylobiose and 1,3-xylotriose. This study reveals the diversity of marine bacteria involved in the degradation and utilization of 1,3-xylan, helpful in our understanding of the recycling of 1,3-xylan driven by bacteria in the ocean and the discovery of novel 1,3-xylanases.

Risk assessment of insect pest expansion in alpine ecosystems under climate change.

BACKGROUND: Growth in insect pest populations poses a significant threat to ecosystem functions and services, societal development, and food security in alpine regions under climate change. Risk assessments are important prioritization tools for pest management, which must be used to study insect pest expansion in alpine ecosystems under global warming. We used species distribution modeling to simulate the current and future distribution probabilities of 58 insect pest species in the Qinghai Province, China, based on a comprehensive field investigation. Subsequently, general linear modeling was used to explore the relationship between the distribution probability of these species and the damage caused by them. Finally, we assessed the ecological risk of insect pest expansion across different alpine ecosystems under climate change. RESULTS: Climate change could increase the distribution probabilities of insect pest species across different alpine ecosystems. However, the presence of insect pest species may not correspond to the damage occurrence in alpine ecosystems based on percent leaf loss, amount of stunting, and seedling death of their host species. Significant positive relationships between distribution probability and damage occurrence were found for several of the examined insect pest species. Insect pest expansion is likely to increase extensively in alpine ecosystems under increasing carbon dioxide (CO2 ) emission scenarios. CONCLUSION: The relationships between distribution probability and damage occurrence should be considered in species distribution modeling for risk assessment of insect pest expansion under climate change. Our study could improve the effectiveness of risk assessment of insect pest expansion under changing climate conditions. © 2021 Society of Chemical Industry.

Ultra-Uniform and Very Thin Ag Nanowires Synthesized via the Synergy of Cl-, Br- and Fe3+ for Transparent Conductive Films.

The properties and applications of Ag nanowires (AgNWs) are closely related to their morphology and composition. Therefore, controlling the growth process of AgNWs is of great significance for technological applications and fundamental research. Here, silver nanowires (AgNWs) were synthesized via a typical polyol method with the synergistic effect of Cl-, Br-, and Fe3+ mediated agents. The synergistic impact of these mediated agents was investigated intensively, revealing that trace Fe3+ ions provided selective etching and hindered the strong etching effect from Cl- and Br- ions. Controlling this synergy allowed the obtainment of highly uniform AgNWs with sub-30 nm diameter and an aspect ratio of over 3000. Transparent conductive films (TCFs) based on these AgNWs without any post-treatment showed a very low sheet resistance of 4.7 Ω sq-1, a low haze of 1.08% at a high optical transmittance of 95.2% (at 550 nm), and a high figure of merit (FOM) of 1210. TCFs exhibited a robust electrical performance with almost unchanged resistance after 2500 bending cycles. These excellent high-performance characteristics demonstrate the enormous potential of our AgNWs in the field of flexible and transparent materials.

Progestin-primed ovarian stimulation improves the outcomes of IVF/ICSI cycles in infertile women with diminished ovarian reserve.

BACKGROUND: Ovarian stimulation with clomiphene (CC) or progestin has been applied for patients with diminished ovarian reserve (DOR). However, it remains unclear which treatment confers greater benefits. This study aimed to compare the outcomes of progestin-primed ovarian stimulation (PPOS) protocol vs CC-primed ovarian stimulation (CPOS) in infertile women with DOR. METHODS: A before-and-after self-controlled study was conducted to retrospectively investigate the data from 50 infertile women with DOR, who failed to conceive in their first in vitro fertilization/intracytoplasmic sperm injection-frozen embryo transfer cycle when stimulated with CPOS, and switched to PPOS, in the Reproductive Medicine Center of Changzhou Maternal and Child Health Care Hospital. RESULTS: Our results showed that PPOS significantly suppressed the luteinizing hormone (LH) surge and yielded more satisfactory results in patients with DOR, including increased number of retrieved oocytes, MII mature oocytes, normal fertilized oocytes, cleaved embryos, high-grade embryos, cryopreserved embryos, pregnancy rate, live-birth rate, and decreased miscarriage rates. CONCLUSION: Our study demonstrated that compared with CPOS protocol, PPOS protocol could not only suppress the LH surge but also improved the quantity, particularly the quality of oocytes in patients with DOR, suggesting that PPOS treatment is more effective than CPOS for patients with DOR.

Liposomes formulated with fMLP-modified cholesterol for enhancing drug concentration at inflammatory sites.

Improving efficacy of inflammation treatment by increasing drug delivery to the inflammatory sites is a challenging endeavor. N-formyl-methionyl-leucyl-phenylalanine (fMLP), the first discovered leukocyte chemotaxis peptide, is composed of formyl methionine, leucine and phenylalanine. It conjugates with formyl peptide receptors on the target cells with high receptor expression on the surface such as macrophages. With this in mind, we developed a novel fMLP-modified liposome (fMLP-LIP) for enhancing drug delivery to the inflammatory sites and resolving the systemic reaction issue with conventional anti-inflammatory drugs. Being a more stable and cheaper liposomal component than phospholipids, cholesterol (CHO) has been thoroughly investigated as an alternative anchor. In this study, fMLP was covalently conjugated with CHO with polyethylene glycol link to prepare the liposomes, cellular uptake of liposomes by differentiated human U937 cells was examined and cellular uptake experiment in vitro was employed to optimize fMLP-LIP prescription and investigate the uptake mechanism. An in vivo inflammatory model was established to evaluate the targeting performance of fMLP-LIP to inflammatory site. The in vitro and in vivo findings indicate that the fMLP ligands playing an important role in increasing drug delivery to inflammatory sites and fMLP-LIP as a promising anti-inflammatory drug carrier.

Atorvastatin calcium in combination with methylprednisolone for the treatment of multiple sclerosis relapse.

This study aimed to investigate the efficacy of combined atorvastatin calcium and methylprednisolone for the treatment of multiple sclerosis relapse. Patients with multiple sclerosis (MS) at the relapse phase were randomized to receive either combined treatment of atorvastatin calcium and methylprednisolone (n = 19) or methylprednisolone alone (n = 19). Expanded Disability Status Scale (EDSS) was administered at baseline, 1 week, 2 weeks, 4 weeks, 3 months, and 6 months after treatment initiation. The number and volume of brain lesions were evaluated using magnetic resonance imaging at baseline and 6 months. The levels of IL-13, IL-35, IFN-γ, and IL-10 in the cerebrospinal fluid were examined using the enzyme-linked immunosorbent assay method. There was no significant difference in EDSS scores at 1, 2, and 4 weeks. At 3 and 6 months, the combined treatment group showed significantly lower EDSS scores than the monotherapy group (P < 0.05). The number and volume of brain lesions in the combined treatment group were significantly lower than the monotherapy group at 6 months (P < 0.001). The mean time to relapse was significantly extended in the combined treatment group than the monotherapy group (P < 0.001). At 2 and 4 weeks, the combined treatment group had significantly higher levels of IL-13, IL-35, and IL-10 in the cerebrospinal fluid than the monotherapy group (P < 0.05), but significantly lower level of IFN-γ (P < 0.001). The levels of IL-13 and IL-10 in the combined treatment group were positively correlated with EDSS scores (r = 0.632, P = 0.001; r = 0.731, P = 0.002). Combined treatment with atorvastatin calcium and methylprednisolone can improve the outcomes of MS relapse compared with glucocorticosteroid alone.

[A case-control study on the duration of sleeping and cerebral infarction].

OBJECTIVE: To explore the relationship between duration of sleeping and cerebral infarction. METHODS: A case-control study involved 1037 cerebral infarction patients admitted by the Second Affiliated Hospital of Harbin Medical University,December 2011-December 2012 as cases. Another 1205 adults free from cerebro-vascular diseases who had undergone physical examination in the hospital at the same period, were served as controls. All the subjects were interviewed with unified questionnaire. Chi-square test, u-test and multivariate logistic regression analysis were performed. RESULTS: After adjustment for potential confounding factors including age, sex, body mass index, wrist-hip ratio, smoking, alcohol intake, hypertension, diabetes mellitus, coronary artery disease and lipid parameters, data from the multivariate logistic regression analysis showed that the risk of cerebral infarction was greater in people who slept less than 6 hours per night than those who slept between 6 hours and 8 hours per night, with an odds ratio (95% CI)as 2.81 (95% CI:1.68-4.70). There was no significant association between factor as 'sleeping longer than 8 hours/pre day' and cerebral infarction. Through the subgroup analysis, data showed that the association between 'shorter than 6 hour sleep/night' and cerebral infarction consistently existed, across the categories of sex, and the degree of association was greater in women than in men, with the odds ratio as 5.58 (95% CI: 1.78-17.52) and 2.00 (95% CI:1.10-3.64) respectively. CONCLUSION: Short sleeping duration might increase the risk of developing cerebral infarction.

Replication and pathogenicity of attenuated human metapneumovirus F mutants in severe combined immunodeficiency mice.

This study was to evaluate the replication and pathogenicity of attenuated human metapneumovirus (HMPV) mutants in severe combined immunodeficiency (SCID) mice. SCID mice were intranasally infected with either wild type GFP-rHMPV (WT), or mutant viruses (M1, M2 and M4) with the N-linked glycosylation(s) of the F protein removed. The organs were collected for viral isolation, titration, pulmonary histopathology and mRNA detection by PCR at different time points. WT or mutant viruses were successfully isolated from the lungs of infected mice after inoculation. The titers of WT and M1 peaked on 5th day and remained detectable until 14th day post-inoculation. M2 reached approximately 4 logs lower titer on 5th and 9th day post-inoculation as compared to WT and M1. M4 showed similar growth kinetics to M2. Viral signal was never detected from the heart, liver, spleen, kidney and brain on 5th day post-inoculation. The pulmonary pathology score in the M1 infected mice was similar to WT infected mice but higher than in M2 or M4 infected mice. WT and HMPV mutants can thus only replicate in the lungs of SCID mice. Attenuated M2 and M4 may be considered as candidates for the preparation of vaccine against HMPV.

[Analysis on variation of hemagglutinin genes of sixteen H9N2 subtype avian influenza viruses isolated in Shandong area].

In order to explore the genetic mutations of the H9N2 subtype avian influenza viruses isolated in Shandong, sixteen avian influenza virus subtype H9N2 were isolated from different areas of Shandong Province. The complete HA fragments of the viruses were amplified by RT-PCR and the sequences were analyzed on homology and heredity evolution after the cloning and sequencing of the products. The results showed that the amino acid motif of cleavage sites for all the sixteen virus in the HA gene were RSSR decrease GLF, which was consistent with the characterization of the LPAIV. Seven to nine potential glycosylation sites were found during the analysis and the receptor binding sites were relatively conservative except the 198 site. The Leucine(L) at the amino acid position 234 in the HA genes of all isolates indicated the potential of binding with SAalpha,2-6 receptor of mammals. Homology analysis showed that the homology of HA nucleotide and amino acid sequences was 96.3%-99.9% and 97.1%-99.6% for different strains. They belonged to a branch of the A/Duck/Hong Kong/Y280/97 in the phylogenetic tree.

[Analysis of viral etiology of severe pneumonia in infants and young children in Chongqing area].

OBJECTIVE: To investigate the prevalence of viral infections and putative association of viral infection with illness severity in young children with severe lower respiratory tract infection (LRTI) in Chongqing. METHOD: Respiratory secretion specimens were collected from 119 hospitalized patients with severe pneumonia from December 2006 to March 2008.After being processed, the samples were detected for respiratory viruses including respiratory syncytial virus (RSV), adenovirus (ADV), human metapneumovirus (hMPV), human bocavirus (HBoV), parainfluenza virus 1, 2, 3 (PIV 1, 2, 3), influenza virus A and B (IVA and IVB) either by PCR or RT-PCR. Clinical data were analyzed along with virological data by using appropriate statistical methods. RESULT: Viral pathogens were identified in specimens of 86 (72.3%) cases, among which RSV was detected in 49 (41.2%) patients. More than one virus was detected in 23 individual (26.7%) samples, of which 19 were dual positive for RSV and another virus. Bacterial cultures were performed for 69 patients. Both bacterial and viral pathogens were identified in 53 (76.8%) patients. Bacterial and viral coinfection was demonstrated in samples from 41 (59.4%) cases. CONCLUSION: Viral pathogens are the main etiology of severe pneumonia in young children in Chongqing area during the study period. RSV was the most frequent viral pathogens, followed by ADV and hMPV. Coinfection with respiratory common viruses was relatively common, though co-infection with viruses did not appear to aggravate the patients' condition.