[Relationship between etiology and morphological classification of benign central airway stenosis and its prognosis]

Objectives: To analyze the relationship between etiology and morphological classification of benign central airway stenosis and its prognosis. Methods: We performed a retrospective study of the medical records of 453 patients initially diagnosed with benign airway stenosis at Department of Respiratory Diseases in Beijing Tiantan Hospital affiliated to Capital Medical University from January 2003 to October 2019. Of 453 patients, 260 were male. The age of the study population was 12-86(44.0±24.5) years. Results: Among the 453 patients diagnosed with benign central airway stenosis, 161 case (35.5%, including 113 post-tracheostomy tracheal stenosis and 48 post-intubation tracheal stenosis) were iatrogenic; 88 cases were from benign tumors (19.4%), 77 cases from tracheal or bronchial tuberculosis (17.0%), 71 case from tracheal foreign bodies (15.7%). Disease causes varied among different gender or age groups. The main type of stenosis was structural stenosis, of which 241 cases (53.2%) were intra-luminal and 183 cases (40.4%) were scar contracture type. The site of stenosis showed a certain relationship with the causes of stenosis. The stenosis degree was mainly from grade 2 to grade 4 (76.4%), and the length was mainly within 3 cm (84.8%). Single factor analysis on the relationship between disease cause, morphological classification and prognosis of benign central airway stenosis showed statistically better prognosis in groups that were caused by benign tumor, intraductal stenosis or stenosis that were 3-4 in degree and 1-2 degree in length. Conclusion: The common causes of central airway stenosis included iatrogenic stenosis, benign tumor, tracheal or bronchial tuberculosis and tracheal foreign bodies. Benign airway stenosis with different disease causes and morphological classification had different prognosis after bronchoscopic interventional treatment. Clinicians should know the disease causes, morphological characterization and risk factors for benign airway stenosis for earlier diagnosis, treatment or prevention.

CXCL12/CXCR4 Mediates Orthodontic Root Resorption via Regulating the M1/M2 Ratio

Mechanical force-induced external root resorption is a major clinical side effect of orthodontic treatment. Recent work has revealed that M1 macrophages play a vital role in promoting orthodontic root resorption (ORR), but the mechanism of how mechanical force stimulation increases the M1/M2 macrophage ratio in periodontal tissue is poorly understood. In the current study, we showed that C-X-C motif chemokine 12 (CXCL12)⁺ periodontal ligament cells (PDLCs) and C-X-C chemokine receptor type 4 (CXCR4)⁺ monocytes in the periodontal ligament (PDL) were significantly increased after force application with ongoing root resorption, and these effects were partially rescued after force removal in mice. The expression of CXCL12 in PDLCs was increased by force stimulation in a time- and intensity-dependent manner in vitro. Blockage of the CXCL12/CXCR4 axis using CXCR4 antagonist AMD3100 was sufficient to alleviate ORR and reverse the force-enhanced M1/M2 macrophage ratio. Further mechanism exploration showed that Ly6C^hi inflammatory monocytes homed in a CXCL12/CXCR4 axis-dependent manner. The number and proportion of CD11b⁺ Ly6C^hi inflammatory monocytes in cervical lymph nodes were significantly increased by force loading, accompanied by decreased CD11b⁺ Ly6C^hi monocytes in the blood. These changes were blunted by intraperitoneal injection of AMD3100. In addition, blockage of the CXCL12/CXCR4 axis effectively reversed M2 suppression and promoted M1 polarization. Collectively, results indicate that force-induced CXCL12/CXCR4 axis mediates ORR by increasing the M1/M2 ratio in periodontal tissues through attracting Ly6C^hi inflammatory monocytes and modulating macrophage polarization. The results also imply that AMD3100 is potentially inhibitory to root resorption.

[Clinical and prognosis analysis of children with kidney retransplantation]

Objective: To analyze the clinical and prognosis of children with kidney retransplantation. Methods: Clinical data of 11 children who underwent kidney retransplantation from January 2011 to December 2020 in Department of Nephrology, Children's Hospital of Fudan University were retrospectilely analyzed. The clinical data including demographic parameters, primary diagnosis, characteristics in the follow-up of renal allograft were analyzed. Results: Totally 11 cases received secondary renal transplantation (male 6, female 5). They were initially diagnosed with chronic kidney disease at the age of 11.9 (7.4, 13.3) years. The median duration of dialysis was 22.1 (3.5, 36.5) months. In the first transplantation, recipient age was 13.9 (11.1, 15.2) years. Ten cases received donation from cardiac death donor (DCD) (9 cases received donors aged less than one year, 5 of them received whole kidney transplantation and one case received donor aged one to three years) and 1 case with living-related donor. Ten graft failures occurred within 1 month after renal transplantation and the other one occurred at the fifth month after transplantation. The causes included vascular factors (9 cases), rejection (1 case) and primary non-function (1 case). In the second transplantation, recipient age was 14.7 (11.7, 16.2) years. All the 11 children received dialysis (7 with PD and 4 with HD) and successfully completed the second transplantation. The median time between the two transplants was 210 (16, 1 041) days. Donors were all DCD donors from 3 years of age or older. The mean follow-up duration was (42±15) months. The estimated glomerular filtration rate was (85±34)ml/(min·1.73 m²) when the last investigation after kidney retransplantation with the kidney and patient all survived. Conclusions: Kidney retransplantation may have better prognosis in children. Dialysis transition during waiting period and DCD donor from 3 years of age or older can effectively ensure the success of kidney retransplantation.

Tribological and corrosion performance of the plasma-sprayed conformal ceramic coating on selective laser melted CoCrMo alloy

Ceramic implants have superior performance due to the excellent wear resistance and biocompatibility. However, the poor machinability limits their applications. Plasma sprayed ceramic coating on the additively manufactured metal substrate not only provides a 3-dimensional conformal implant coating and but also forms a highly wear-resistant surface layer. In this paper, three types of ceramic coatings of Al₂O_3, ZrO₂, and Al₂O₃-ZrO₂ composite have been fabricated by atmosphere plasma spray on the CoCrMo alloy substrate prepared by selective laser melting (SLM). It has been found that the Al₂O₃-ZrO₂ composite coating has better corrosion and wear resistance compared with the ceramic coating (Al₂O_3, ZrO₂) and the CoCrMo substrate. The adhesion strength between the Al₂O₃-ZrO₂ composite coating and the substrate reaches 238 MPa. In addition, the wear and corrosion resistance increase with wear progression for all the fabricated ceramic coatings. The highly dense microstructure, fewer microcracks, and the amorphous phases are deterministic factors responsible for the superior tribological and corrosion performance of the Al₂O₃-ZrO₂ composite coating. The fabrication route has been proved very promising to manufacture high-performance implants with ceramic coating.

Energy value of rice, broken rice, and rice bran for broiler chickens by the regression method

The objective of this study was to determine the ileal digestible energy (IDE), ME, and ME_n of rice, broken rice, and rice bran. The birds were fed a standard starter diet from day 0 to 14 and experimental diets from day 15 to 21 after hatching. A total of 336 birds were grouped by BW and assigned to 7 diets, each diet comprised 8 replicates with 6 birds per replicate. The diets comprised a reference diet (RD) and 6 test diets (TD). The TD contained 2 levels of rice, broken rice or rice bran that partly replaced the energy sources in the RD at 120 or 240 g/kg (rice and broken rice) or 150 or 300 g/kg (rice bran). Addition of rice or broken rice to RD linearly increased (P < 0.01) ileal digestibility of DM, energy, as well as total tract metabolizability of DM, energy, and N-corrected energy in the TD. The inclusion of rice bran in the TD linearly decreased (P < 0.01) energy digestibility and utilization in the test diet. Regressions of rice-associated, broken rice-associated, or rice bran-associated IDE, ME, or ME_n intake in kcal against rice, broken rice, or rice bran intake were as follows: IDE = Y = 2 (6) + 3,185 (73) × Rice + 3,199 (72) × Broken Rice + 2,562 (61) × Rice Bran, r2 = 0.98; ME = Y = 8 (6) + 3,103 (72) × Rice + 3,190 (71) × Broken Rice + 2,709 (60) × Rice Bran, r2 = 0.98; ME_n = Y = 4 (5) + 3,014 (68) × Rice + 3,092 (101) × Broken Rice + 2,624 (57) × Rice Bran, r2 = 0.98; Based on the regression equations, the IDE, ME, ME_n values (kcal/kg of DM) of rice were 3,185, 3,103 and 3,014, respectively, while for broken rice, the values were 3,199, 3,190, and 3,092 and for rice bran, the values were 2,562, 2,709, and 2,624, respectively.

[Spatial-temporal characteristics of other infectious diarrhea in Jiangsu province, 2010-2017]

Objective: To analyze the spatial-temporal characteristics of other infectious diarrhea (OID) in Jiangsu province from 2010 to 2017, and to provide evidence for setting up prevention and control programs of the disease. Methods: Data was from the Chinese Center for Disease Control and Prevention and the Statistics Bureau of Jiangsu province. Descriptive methods were used to illustrate the epidemiological characteristics of OID from 2010 to 2017. Global autocorrelation statistics method (Moran's I) was used to detect the spatial autocorrelation of OID, annually. Kulldorff M spatiotemporal scan statistics was used to analyze the spatial-temporal clustering of OID. ArcGIS 10.0 software, SaTScan 9.4 software and Excel 2017 software were also applied. Results: A total of 126 341 OID cases were found in Jiangsu province from 2010 to 2017 with an average annual incidence as 19.96/100 000. Children under five accounted for 55.08% (69 590/126 341) of the total cases. Obvious seasonal backshift with the increasing trends of the OID was noticed. There appeared four areas with high incidence of OID in the whole province, including Wuxi, Suzhou, Yancheng and Xuzhou. OID showed positive spatial autocorrelation at the county level with higher Moran's I from 0.19 to 0.33 (P<0.01). There appeared four positive clusters, all occurred in the high incidence period of OID, including the cluster area from the intersection areas of Changzhou and Wuxi (RR=7.61, LLR=2 605.80, P<0.01), respectively. Conclusion: With the increasing trends and the seasonal backshift of OID cases, pathogen surveillance programs set for those scattered children under five, in clustered regions and epidemic seasons should be strengthened.

[Role of erythroblast-like Ter cells in the pathogenesis of collagen-induced arthritis]

OBJECTIVE

To explore the role of Ter cells in the development of the collagen-induced arthritis (CIA), we detected their quantity changes in the spleen of different stages of CIA mice and analyzed the correlation between Ter cells and the joint scores, and we also analyzed the correlation between Ter cells and the frequencies of T and B cell subsets, so as to further understand the pathogenesis of rheumatoid arthritis.

METHODS

The six to eight weeks DBA/1 mice were used to prepare CIA model. After the second immunization, we began to evaluate the joint score. According to the time of CIA onset and the joint score, the CIA mice were divided into three stages: early, peak and late stages. According to the final joint score, the CIA mice at the peak stage were subdivided into the high score group (score>8) and the low score group (score≤8). The frequencies of Ter cells in the spleen of the naïve mice and the CIA mice at various stages and the frequencies of T and B cell subsets in the spleen of the CIA mice at the peak stage were detected by flow cytometry, then we carried on the correlation analysis.

RESULTS

The frequencies of Ter cells in the spleen of the CIA mice was significantly higher than those of the naïve mice (8.522%±2.645% vs. 1.937%±0.725%, P<0.01), the frequencies of Ter cells in the spleen of the high score group mice was significantly lower than those of the low score group (6.217%±0.841% vs. 10.827%±0.917%, P<0.01). The frequencies of Th1 cells in the spleen of the high score group mice was significantly higher than those of the low score group mice (1.337%±0.110% vs. 0.727%±0.223%, P<0.05). The frequencies of Th17 cells in the spleen of the high score group mice was higher than those of the low score group mice (0.750%±0.171% vs. 0.477%±0.051%, P=0.099). The frequencies of germinal center B cells in the spleen of the high score group mice was significantly higher than those of the low score group mice (1.243%±0.057% vs. 1.097%±0.015%, P<0.05). Correlation analysis results showed that the frequencies of Ter cells in the spleen of the CIA mice at the peak stage was strongly negatively correlated with the frequencies of CD4+ T, Th1, Th17, and germinal center B cells, and was strongly positively correlated with the frequencies of B10 cells, indicating that these cells might have a protective effect in CIA. Studies on dynamic changes showed that the frequencies of Ter cells in the spleen of the CIA mice at the late stage was significantly lower than those at the peak stage (0.917%±0.588% vs. 8.522%±2.645%, P<0.001), suggesting the protective effect of these cells in arthritis.

CONCLUSION

Ter cells were significantly increased in the spleen of the CIA mice at peak stage, and were negatively correlated with joint scores and pathogenic immune cells, and positively correlated with protective immune cells. Ter cells were significantly decreased in the spleen of the CIA mice at the late stage. What we mentioned above suggests that Ter cells might be involved in the progression of rheumatoid arthritis as an immunomodulatory cell,but further in vivo and in vitro experiments are needed to verify its specific effects and mechanism.

Cumulative effect of depressed mood and obesity on type II diabetes incidence: Findings from the MONICA/KORA cohort study

BACKGROUND

Obesity and depression both individually contribute to the risk of Type II Diabetes (T2DM). The extent to which obesity can be set-off by depression is unknown.

METHODS

In a sample of 9340 participants followed for 15.4 years (79,372 person-years) from the prospective MONICA/KORA population-based cohort conducted in Southern Germany, we investigated the impact of obesity, defined as Body Mass Index (BMI) ≥ 30, and depression on the incidence of T2DM using Cox Proportional Hazards Regression.

RESULTS

The relative risk of T2DM was over 6 fold higher among obese participants in comparison to normal weight participants (HR 6.05; 95% CI 4.82 to 7.59; p < .0001). Nonetheless, among participants with obesity, comorbidity of depression was associated with an additional 2 fold risk T2DM (HR 8.05, 95% CI 5.90-10.98; p < .0001). This finding corresponded to an increase in the 15.4-year absolute risk of T2DM from 15.9 cases per 1000 person-years (py) in participants with obesity but not depression, to 21.4 cases per 1000 py for participants with obesity and depression. Further analysis of joint effects and Relative Excess Risk due to Interaction disclosed that depressed mood is associated with significantly higher risk of T2DM in participants with obesity, and to a lesser extent in overweight participants, however an association was not found in normal weight participants.

CONCLUSIONS

The present investigation discloses that despite the overreaching importance of obesity as a risk factor for T2DM, there is room for depressed mood to add measurable risk prediction.

Effect of polydatin on expression of p53 and Notch1 in brain tissue of ischemic cerebrovascular disease

Secondary injury of brain tissue following cerebral infarction exhibits a complicated pathogenesis that is attributed to the induction of apoptosis and inflammatory response. The present study aimed to investigate the polydatin neuroprotective effects and their mode of action in cerebral ischemic injury. A total of 80 healthy adult male Sprague-Dawley rats were randomly divided into a Sham operated group, a permanent middle cerebral artery occlusion (MCAO) group, a Polydatin low dose group and a Polydatin high dose group. A total of 20 rats were used in each group. The right MCAO model of rats was established using the modified Longa suture method. The animals in the intervention group were injected intraperitoneally with 12.5mg/kg and/or 50mg/kg of polydatin following infarction. The expression levels of p53 and Notch 1 were measured by immunohistochemical techniques. The degree of left limb hemiplegia in the MCAO group was different compared with that of the low and high dose group of polydatin. The score for the neurological function in the high-dose group of polydatin was lower than that in the MCAO group (High vs MCAO: 2.4±0.31 vs 3.9±0.23, P less than0.05). The results indicated that high dose polydatin could reduce brain edema following cerebral infarction and improve the behavioral score in rats.

Surface integrity and corrosion performance of biomedical magnesium-calcium alloy processed by hybrid dry cutting-finish burnishing

Biodegradable magnesium-calcium (MgCa) alloy is a very attractive orthopedic biomaterial compared to permanent metallic alloys. However, the critical issue is that MgCa alloy corrodes too fast in the human organism. Compared to dry cutting, the synergistic dry cutting-finish burnishing can significantly improve corrosion performance of MgCa0.8 (wt%) alloy by producing a superior surface integrity including good surface finish, high compressive hook-shaped residual stress profile, extended strain hardening in subsurface, and little change of grain size. A FEA model was developed to understand the plastic deformation of MgCa materials during burnishing process. The measured polarization curves, surface micrographs, and element distributions of the corroded surfaces by burnishing show an increasing and uniform corrosion resistance to simulated body fluid.

[Research on hallucinogenic drugs used in Shaman religious activities]

The development of medicine experienced a long history, and the origin of medicine is not appeared overnight. Due to the lack of historical data, the question of the origin of medicine has not been agreed upon. As an ancient primitive religion, Shamanism retains the use of hallucinogenic drugs in its early religious activities rather well, providing a guidance for exploring the cognition on drugs in early human. Through the review of the hallucinogenic plants used by shaman religious activities in different countries and areas, it was found that hallucinogenic drugs can be classified into two categories: single and mixed, which came mainly from plants and fungi, and the origin of hallucinogenic drugs has a high fitting degree with Shaman location. The study result suggests that, based on the worldwide research literature on the application of such hallucinogens with local characteristics in the shamanistic religious activities, it is very likely that important clues can be found to understand the facts of discovery and application of natural drugs, thus providing a new approach for the studies on the origin of drugs.

[Coenzyme Q(10) treatment for one child with COQ6 gene mutation induced nephrotic syndrome and literature review]

Objective: To summarize the clinical manifestation and molecular characteristics of COQ6 mutation induced nephrotic syndrome, and to evaluate efficacy of CoQ(10) therapy. Method: Clinical data of the case with infantile nephrotic syndrome was summarized, including clinical manifestations, laboratory findings and family investigation. The patient received CoQ(10) 30 mg/(kg·d) therapy. Urine protein/creatinine ratio, serum albumin and creatinine were detected to assess the efficacy of the therapy. Result: (1) The 10 months old boy was presented with nephrotic level proteinuria and hypoalbuminemia. Extra-renal manifestations included cardiovascular abnormality, motor and mental retardation and unilateral ptosis. The patient had no consanguinity. A novel homozygous p. R360W mutation in COQ6 gene was identified and confirmed by next-generation sequencing and Sanger sequencing, respectively. Family analysis showed that homozygous p. R360W mutation in COQ6 gene was inherited from his parents. Missense p. R360W mutation was damaging by prediction online PolyPhen and SIFT software. After 2 months of CoQ(10) complementary therapy, the patient's urine protein/creatinine ratio declined from 7.2 to 1.3, and decreased further to 0.01 mg/mg with normal albumin level and renal function within 3 months. Nephropathy remission was maintained and growth retardation improved significantly during the last follow-up. Nevertheless, the patient manifested with sensorineural deafness at the age of 2 years. (2) There were 6 different mutations in coenzyme Q(10) biosynthesis monooxygenase 6 (COQ6) in 13 individuals from 7 families by homozygosity mapping in the whole world. Each mutation was linked to early-onset SRNS with sensorineural deafness. Renal biopsy revealed FSGS in 7 cases and DMS in 1 case. Other manifestations included ataxia, seizures, facial dysmorphism, nephrolithiasis and growth retardation. Four patients received CoQ(10) supplementation and responded to the treatment. Conclusion: Renal disease caused by recessive COQ6 gene mutation was nephrotic syndrome. The patient benefited from early CoQ(10) complement and reached nephropathy remission.

Is denial a maladaptive coping mechanism which prolongs pre-hospital delay in patients with ST-segment elevation myocardial infarction?

OBJECTIVE

During an acute myocardial infarction, patients often use denial as a coping mechanism which may provide positive mood regulating effects but may also prolong prehospital delay time (PHD). However, empirical evidences are still sparse.

METHODS

This cross-sectional study included 533 ST-elevated myocardial infarction (STEMI) patients from the Munich Examination of Delay in Patients Experiencing Acute Myocardial Infarction (MEDEA) study. Data on sociodemographic, clinical and psycho-behavioral characteristics were collected at bedside. The outcome was assessed using the Cardiac Denial of Impact Scale (CDIS) with the median split as cutoff point. A total of 206 (41.8%) STEMI patients were thus classified as deniers.

RESULTS

Deniers were less likely to suffer from major depression (p=0.04), anxiety (p=0.01) and suboptimal well-being (p=0.01) compared to non-deniers during the last six months prior to STEMI. During STEMI, they were less likely to perceive severe pain strength (p=0.04) and racing heart (p=0.02). Male deniers were also less likely to perceive shortness of breath (p=0.03) and vomiting (p=0.01). Denial was not associated with overall delay time. However, in the time window of 3 to 24h, denial accounted for roughly 40min extra delay (356 vs. 316.5min p=0.02 n=196).

CONCLUSIONS

Denial not only contributes to less suffering from acute heart related symptoms and negative affectivity but also leads to a clinically significant delay in the prevalent group.

Dimensional Effects on the Charge Density Waves in Ultrathin Films of TiSe2

Charge density wave (CDW) formation in solids is a critical phenomenon involving the collective reorganization of the electrons and atoms in the system into a wave structure, and it is expected to be sensitive to the geometric constraint of the system at the nanoscale. Here, we study the CDW transition in TiSe₂, a quasi-two-dimensional layered material, to determine the effects of quantum confinement and changing dimensions in films ranging from a single layer to multilayers. Of key interest is the characteristic length scale for the transformation from a two-dimensional case to the three-dimensional limit. Angle-resolved photoemission spectroscopy (ARPES) measurements of films with thicknesses up to six layers reveal substantial variations in the energy structure of discrete quantum well states; however, the temperature-dependent band gap renormalization converges at just three layers. The results indicate a layer-dependent mixture of two transition temperatures and a very-short-range CDW interaction within a three-dimensional framework.

[Clinical analysis of 39 cases who received transplantation of kidney from pediatric organ donors]

OBJECTIVE

To explore the feasibility and clinical significance of pediatric renal transplantation using organ donations from pediatric patients donors.

METHOD

Clinical data of children who underwent renal transplantation using organ donations from pediatric patients between September 2011 and December 2014 were retrospectively analyzed, including diagnosis and treatment before transplant, transplant operation, immunosuppression, complication and prognosis.

RESULT

Totally 39 cases received pediatric organ donation-pediatric kidney transplantation. The median age at transplantation was 10.5 years. Before transplantation, 37 cases received chronic dialysis. The median waiting time for transplantation was 15 months. The 39 cases received kidneys from 29 donors who were aged from 9 days to 7 years (median 13 months). The median duration of follow-up after the transplantation was 19 months. At 3 month after transplantation and latest follow-up, the length of graft increased (11.3±6.4) mm and (17.5±10.8) mm, respectively. At 6 month and 12 month after transplantation, the height of the recipients increased (5.8±3.5) cm and (15.0±3.5) cm, respectively. At latest follow-up, the serum creatinine level was (80.3±31.9) μmol/L and the eGFR was (94.4±32.9) ml/(min·1.73 m(2)). The recipient survival rate was 100% and grafts survived in 34 cases; 3 cases lost graft function due to thrombosis of renal vessels and the other 2 cases due to bleeding and chronic allograft nephropathy. Donor age of less than 12 months carried higher risk of thrombosis/hemorrhagic complication (P=0.042) and graft dysfunction (P=0.017).

CONCLUSION

Favorable outcome can be obtained from pediatric organ donation-pediatric kidney transplantation. Patient survival rate reached 100% at one-year and three-year graft survival rate was 87%. The size of the allograft would increase and the height of the recipients would improve after transplantation.

[The contrast analysis of endoscopic thyroidectomy by complete areola approach and conventional open thyroidectomy]

Objective:To compare the clinical efficacy between the endoscopic thyroidectomy by complete areola approach and the conventional open thyroidectomy.Method:One hundred and twenty-one cases of endoscopic thyroidectomy by complete areola approach or conventional open thyroidectomy patients were reviewed retrospectively, whose operation time, median blood lose, volume of postoperative drainage, incision scar formation rate and patient satisfaction were observed and compared.Result:There were obvious advantages in the median blood lose, volume of postoperative drainage, incision scar formation rate and patient satisfaction in the group of endoscopic thyroidectomy by complete areola approach comparing conventional open thyroidectomy. The difference was statistically significant（P <0.05）.Conclusion:The method of endoscopic thyroidectomy by complete areola approach is obviously better , which has many advantages, such as Less bleeding, less volume of wound drainage and small skin incision scar. The patients were satisfied with the treatment.It is worthy of clinical application.

Charge density wave transition in single-layer titanium diselenide

A single molecular layer of titanium diselenide (TiSe₂) is a promising material for advanced electronics beyond graphene—a strong focus of current research. Such molecular layers are at the quantum limit of device miniaturization and can show enhanced electronic effects not realizable in thick films. We show that single-layer TiSe₂ exhibits a charge density wave (CDW) transition at critical temperature T_C=232±5 K, which is higher than the bulk T_C=200±5 K. Angle-resolved photoemission spectroscopy measurements reveal a small absolute bandgap at room temperature, which grows wider with decreasing temperature T below T_C in conjunction with the emergence of (2 × 2) ordering. The results are rationalized in terms of first-principles calculations, symmetry breaking and phonon entropy effects. The observed Bardeen-Cooper-Schrieffer (BCS) behaviour of the gap implies a mean-field CDW order in the single layer and an anisotropic CDW order in the bulk.

Single molecular layers of TiSe₂ are promising for advanced electronic applications, and it is therefore important to characterize their phases. Here, the authors use ARPES to detect a charge density wave transition without Fermi surface nesting and that takes place at a temperature higher than in bulk.

PCR screening reveals considerable unexploited biosynthetic potential of ansamycins and a mysterious family of AHBA-containing natural products in actinomycetes

AIMS

Ansamycins are a family of macrolactams that are synthesized by type I polyketide synthase (PKS) using 3-amino-5-hydroxybenzoic acid (AHBA) as the starter unit. Most members of the family have strong antimicrobial, antifungal, anticancer and/or antiviral activities. We aimed to discover new ansamycins and/or other AHBA-containing natural products from actinobacteria.

METHODS AND RESULTS

Through PCR screening of AHBA synthase gene, we identified 26 AHBA synthase gene-positive strains from 206 plant-associated actinomycetes (five positives) and 688 marine-derived actinomycetes (21 positives), representing a positive ratio of 2·4-3·1%. Twenty-five ansamycins, including eight new compounds, were isolated from six AHBA synthase gene-positive strains through TLC-guided fractionations followed by repeated column chromatography. To gain information about those potential ansamycin gene clusters whose products were unknown, seven strains with phylogenetically divergent AHBA synthase genes were subjected to fosmid library construction. Of the seven gene clusters we obtained, three show characteristics for typical ansamycin gene clusters, and other four, from Micromonospora spp., appear to lack the amide synthase gene, which is unusual for ansamycin biosynthesis. The gene composition of these four gene clusters suggests that they are involved in the biosynthesis of a new family of hybrid PK-NRP compounds containing AHBA substructure.

CONCLUSIONS

PCR screening of AHBA synthase is an efficient approach to discover novel ansamycins and other AHBA-containing natural products.

SIGNIFICANCE AND IMPACT OF THE STUDY

This work demonstrates that the AHBA-based screening method is a useful approach for discovering novel ansamycins and other AHBA-containing natural products from new microbial resources.

First Report of Bacterial Leaf Spot on Snow Lotus Caused by Pseudomonas syringae in China

Snow lotus (Saussurea involucrata (Kar. & Kir.) Sch. Bip.) is an economically important medicinal herb increasingly grown in China in recent years. During the summer and autumn of 2005, 2006, and 2007, a necrosis of unknown etiology was observed on leaves in commercial production areas in Xinjiang Province of China. Disease incidence was approximately 40 to 50% of the plants during the 2005 and 2007 growing seasons. Initial symptoms consisted of pronounced water-soaked, dark brown-to-black spots that were 1 to 2 mm in diameter on young, expanding leaves. Later, some leaf spots on older leaves enlarged and coalesced, causing leaf desiccation. Leaf samples were collected in 2005, 2006, and 2007 from the affected hosts. Bacterial streaming was evident from these samples, and 28 strains were isolated on nutrient agar or King's medium B (KMB). All strains were gram negative and fluoresced bluegreen under UV light after 48 h of growth at 28°C on KMB. On the basis of LOPAT tests, the strains were identified as Pseudomonas syringae (1). The identity of two strains was confirmed by sequencing the 16S rDNA gene, which revealed 98% similarity to P. syringae strains in NCBI (Accession Nos. FJ001817 and FJ001818 for XJSNL 111 and 107, respectively). Infiltration of tobacco leaves with bacterial suspensions resulted in typical hypersensitivity reactions within 24 h. Pathogenicity of the strains was confirmed by spray inoculating five snow lotus leaves of a six-leaf stage plant with 10⁸ CFU ml^-1 bacterial suspensions in sterile water and five plants sprayed with sterile distilled water served as controls. Inoculated and sterile water-sprayed controls were maintained in the growth chamber with 90% relative humidity for 15 days at 15 ± 2°C. Symptoms similar to the original symptoms were observed on inoculated plants after 2 weeks. No symptoms developed on controls. Bacteria reisolated from inoculated plants were identified as strains of P. syringae. Isolates were deposited at the Key Laboratory for Oasis Crop Disease Prevention and Cure, Shihezi University. Rust caused by Puccinia carthami and leaf spot disease caused by Alternaria carthami of snow lotus have been reported (2,3). To our knowledge, this is the first report of P. syringae as the cause of bacterial leaf spot on snow lotus in China. References: (1) A. Braun-Kiewnick and D. C. Sands. Pseudomonas. Page 84 in: Laboratory Guide for the Identification of Plant Pathogenic Bacteria. 3rd ed. N. W. Schaad et al., eds. The American Phytopathological Society, St. Paul, MN, 2001. (2) S. Zhao et al. Plant Dis. 91:772, 2007. (3) S. Zhao et al. Plant Dis. 92:318, 2008.

Effect of Ca(2+)-free and Mg(2+)-free BSS Plus solution on the retinal pigment epithelium and retina in rabbits

PURPOSE

To determine whether intravitreal irrigation with Ca(2+)-free and Mg(2+)-free BSS Plus (Alcon Laboratory, Fort Worth, Texas) solution alters the adhesiveness between the retinal pigment epithelium and the retina of rabbits.

METHODS

Thirty-four eyes of 34 Dutch pigmented rabbits underwent lensectomy and vitrectomy. Subsequently, the vitreous cavity of 24 eyes was irrigated with Ca(2+)-free and Mg(2+)-free BSS Plus solution for 10 or 20 minutes. The other 10 eyes were irrigated with BSS Plus solution for 20 minutes as controls. To determine the adhesiveness between the retinal pigment epithelium and retina, a retinal detachment was produced in 12 of the 34 eyes. The apical surface of the retinal pigment epithelium and the photoreceptor outer segments were examined by scanning electron microscopy. Retinal physiology was assessed by electroretinography and retinal morphology by light microscopy.

RESULTS

After retinal detachment was produced, the number of cone sheaths on the apical surface of the retinal pigment epithelium after irrigation with Ca(2+)-free and Mg(2+)-free BSS Plus solution for 20 minutes (33 +/- 15, mean +/- SD) was significantly less than the number of cone sheaths on the apical surface of the retinal pigment epithelium of eyes after irrigation with BSS Plus solution for 20 minutes (120 +/- 50) or the number of cone sheaths on the apical surface of the retinal pigment epithelium of eyes after 10 minutes of irrigation with Ca(2+)-free and Mg(2+)-free BSS Plus solution (115 +/- 49; P =.02). The b-wave amplitudes in the eyes irrigated with Ca(2+)-free and Mg(2+)-free BSS Plus solution for 20 minutes were depressed compared with the b-waves in eyes irrigated with BSS Plus solution for 20 minutes on the first postoperative day (P =.03). After the third postoperative day, there was no significant difference in the b-waves (P >.06). Light microscopy demonstrated no morphologic abnormalities after the use of both solutions.

CONCLUSIONS

Intravitreal irrigation with Ca(2+)-free and Mg(2+)-free BSS Plus solution for 20 minutes altered the adhesion between the retinal pigment epithelium microvilli and retinal outer segments and made the creation of retinal detachment less traumatic. These results suggest that Ca(2+)-free and Mg(2+)-free BSS Plus solution may be of clinical value for the creation of an intentional retinal detachment for foveal translocation surgery.