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Li YH, Lau PC, Lee JH, Ellen RP, Cvitkovitch DG. Natural genetic transformation of Streptococcus mutans growing in biofilms. J Bacteriol 2001; 183:897-908. [PMID: 11208787 PMCID: PMC94956 DOI: 10.1128/jb.183.3.897-908.2001] [Citation(s) in RCA: 383] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 02/04/2023] Open
Abstract
Streptococcus mutans is a bacterium that has evolved to be dependent upon a biofilm "lifestyle" for survival and persistence in its natural ecosystem, dental plaque. We initiated this study to identify the genes involved in the development of genetic competence in S. mutans and to assay the natural genetic transformability of biofilm-grown cells. Using genomic analyses, we identified a quorum-sensing peptide pheromone signaling system similar to those previously found in other streptococci. The genetic locus of this system comprises three genes, comC, comD, and comE, that encode a precursor to the peptide competence factor, a histidine kinase, and a response regulator, respectively. We deduced the sequence of comC and its active pheromone product and chemically synthesized the corresponding 21-amino-acid competence-stimulating peptide (CSP). Addition of CSP to noncompetent cells facilitated increased transformation frequencies, with typically 1% of the total cell population transformed. To further confirm the roles of these genes in genetic competence, we inactivated them by insertion-duplication mutagenesis or allelic replacement followed by assays of transformation efficiency. We also demonstrated that biofilm-grown S. mutans cells were transformed at a rate 10- to 600-fold higher than planktonic S. mutans cells. Donor DNA included a suicide plasmid, S. mutans chromosomal DNA harboring a heterologous erythromycin resistance gene, and a replicative plasmid. The cells were optimally transformed during the formation of 8- to 16-h-old biofilms primarily consisting of microcolonies on solid surfaces. We also found that dead cells in the biofilms could act as donors of a chromosomally encoded antibiotic resistance determinant. This work demonstrated that a peptide pheromone system controls genetic competence in S. mutans and that the system functions optimally when the cells are living in actively growing biofilms.
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Wang SY, Li YH, Chi GB, Xiao SY, Ozanne-Smith J, Stevenson M, Phillips MR. Injury-related fatalities in China: an under-recognised public-health problem. Lancet 2008; 372:1765-73. [PMID: 18930527 DOI: 10.1016/s0140-6736(08)61367-7] [Citation(s) in RCA: 190] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Academic Contribution Register] [Indexed: 12/01/2022]
Abstract
The May 2008 earthquake in Wenchuan drew attention to the important but largely unrecognised public-health problem of injury-related mortality and morbidity in China. Injuries account for more than 10% of all deaths and more than 30% of all potentially productive years of life lost due to premature mortality in China. Traffic-related injuries (mainly among cyclists and pedestrians), suicide, drowning, and falls account for 79% of all injury deaths. Rural injury death rates are double those of urban rates and male rates are double those of female rates. Despite an 81% increase in the traffic-related mortality from 1987 to 2006-associated with rapid motorisation-the overall injury mortality decreased by 17%, largely due to a surprising (and unexplained) 57% reduction in the suicide rate. Low-cost prevention measures that are most likely to produce large reductions in injury deaths include enforcement of laws for drinking and driving and for seat belt and helmet use, restriction of access to the most potent pesticides, and teaching children to swim. China needs to improve monitoring of fatal and non-fatal injuries, promote intersectoral collaboration, build institutional capacities, and, most importantly, mobilise community support and political will for investment in prevention.
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Albaum MN, Hill LC, Murphy M, Li YH, Fuhrman CR, Britton CA, Kapoor WN, Fine MJ. Interobserver reliability of the chest radiograph in community-acquired pneumonia. PORT Investigators. Chest 1996; 110:343-50. [PMID: 8697831 DOI: 10.1378/chest.110.2.343] [Citation(s) in RCA: 175] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 02/01/2023] Open
Abstract
OBJECTIVE To evaluate the interobserver reliability of pulmonary radiographic findings in patients with community-acquired pneumonia (CAP). DESIGN A prospective, multicenter study. SETTING Physician offices, medical walk-in clinics, emergency departments, and inpatient wards affiliated with three university hospitals, one community hospital, and one staff model health maintenance organization in three geographic areas. METHODS Copies of the initial chest radiograph of patients suspected of having CAP were independently read by two staff radiologists at the coordinating university hospital. Interobserver reliability for the interpretation for radiographic findings was assessed by calculation of agreement rates and the kappa statistic. PARTICIPANTS Adults (age > or = 18 years) with symptoms or signs of CAP and a pulmonary radiographic infiltrate documented by a local study site radiologist. RESULTS Among the 282 patients whose initial pulmonary radiographs were evaluated, there was agreement between the two staff radiologists on the presence of infiltrate in 79.4% and on the absence of an infiltrate in 6.0% (kappa = 0.37; 95% confidence interval [CI] = 0.22 to 0.52). For the 224 patients with an infiltrate identified by both radiologists, there was further agreement that the infiltrate was unilobar in 41.5% and multilobar in 33.9% (kappa = 0.51; 95% CI = 0.28 to 0.62), pleural effusion was present in 10.7% and absent in 73.2% (kappa = 0.46; 95% CI = 0.33 to 0.50), and the infiltrate was alveolar in 96.3% of patients and interstitial in no patients (kappa = -0.01; 95% CI = -0.03 to 0.00). Among the 210 patients with an alveolar infiltrate, both radiologists classified the infiltrate as lobar in 74.6% and bronchopneumonia in 2.4% (kappa = 0.09; 95% CI = -0.04 to 0.22), and agreed on the presence of air bronchograms in 7.6% and their absence in 52.9% (kappa = 0.01; 95% CI = -0.13 to 0.15). CONCLUSION In patients with CAP, two university radiologists identified the presence of infiltrate, multilobar disease, and pleural effusion with fair to good interobserver reliability. However, interobserver reliability for the pattern of infiltrate and the presence of air bronchograms was poor.
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Li YH, Hanna MN, Svensäter G, Ellen RP, Cvitkovitch DG. Cell density modulates acid adaptation in Streptococcus mutans: implications for survival in biofilms. J Bacteriol 2001; 183:6875-84. [PMID: 11698377 PMCID: PMC95529 DOI: 10.1128/jb.183.23.6875-6884.2001] [Citation(s) in RCA: 169] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 11/20/2022] Open
Abstract
Streptococcus mutans normally colonizes dental biofilms and is regularly exposed to continual cycles of acidic pH during ingestion of fermentable dietary carbohydrates. The ability of S. mutans to survive at low pH is an important virulence factor in the pathogenesis of dental caries. Despite a few studies of the acid adaptation mechanism of this organism, little work has focused on the acid tolerance of S. mutans growing in high-cell-density biofilms. It is unknown whether biofilm growth mode or high cell density affects acid adaptation by S. mutans. This study was initiated to examine the acid tolerance response (ATR) of S. mutans biofilm cells and to determine the effect of cell density on the induction of acid adaptation. S. mutans BM71 cells were first grown in broth cultures to examine acid adaptation associated with growth phase, cell density, carbon starvation, and induction by culture filtrates. The cells were also grown in a chemostat-based biofilm fermentor for biofilm formation. Adaptation of biofilm cells to low pH was established in the chemostat by the acid generated from excess glucose metabolism, followed by a pH 3.5 acid shock for 3 h. Both biofilm and planktonic cells were removed to assay percentages of survival. The results showed that S. mutans BM71 exhibited a log-phase ATR induced by low pH and a stationary-phase acid resistance induced by carbon starvation. Cell density was found to modulate acid adaptation in S. mutans log-phase cells, since pre-adapted cells at a higher cell density or from a dense biofilm displayed significantly higher resistance to the killing pH than the cells at a lower cell density. The log-phase ATR could also be induced by a neutralized culture filtrate collected from a low-pH culture, suggesting that the culture filtrate contained an extracellular induction component(s) involved in acid adaptation in S. mutans. Heat or proteinase treatment abolished the induction by the culture filtrate. The results also showed that mutants defective in the comC, -D, or -E genes, which encode a quorum sensing system essential for cell density-dependent induction of genetic competence, had a diminished log-phase ATR. Addition of synthetic competence stimulating peptide (CSP) to the comC mutant restored the ATR. This study demonstrated that cell density and biofilm growth mode modulated acid adaptation in S. mutans, suggesting that optimal development of acid adaptation in this organism involves both low pH induction and cell-cell communication.
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Gnatiuc L, Herrington WG, Halsey J, Tuomilehto J, Fang X, Kim HC, De Bacquer D, Dobson AJ, Criqui MH, Jacobs DR, Leon DA, Peters SAE, Ueshima H, Sherliker P, Peto R, Collins R, Huxley RR, Emberson JR, Woodward M, Lewington S, Aoki N, Arima H, Arnesen E, Aromaa A, Assmann G, Bachman DL, Baigent C, Bartholomew H, Benetos A, Bengtsson C, Bennett D, Björkelund C, Blackburn H, Bonaa K, Boyle E, Broadhurst R, Carstensen J, Chambless L, Chen Z, Chew SK, Clarke R, Cox C, Curb JD, D'Agostino R, Date C, Davey Smith G, De Backer G, Dhaliwal SS, Duan XF, Ducimetiere P, Duffy S, Eliassen H, Elwood P, Empana J, Garcia-Palmieri MH, Gazes P, Giles GG, Gillis C, Goldbourt U, Gu DF, Guasch-Ferre M, Guize L, Haheim L, Hart C, Hashimoto S, Hashimoto T, Heng D, Hjermann I, Ho SC, Hobbs M, Hole D, Holme I, Horibe H, Hozawa A, Hu F, Hughes K, Iida M, Imai K, Imai Y, Iso H, Jackson R, Jamrozik K, Jee SH, Jensen G, Jiang CQ, Johansen NB, Jorgensen T, Jousilahti P, Kagaya M, Keil J, Keller J, Kim IS, Kita Y, Kitamura A, Kiyohara Y, Knekt P, Knuiman M, Kornitzer M, Kromhout D, Kronmal R, Lam TH, Law M, Lee J, Leren P, Levy D, Li YH, Lissner L, Luepker R, Luszcz M, MacMahon S, Maegawa H, Marmot M, Matsutani Y, Meade T, Morris J, Morris R, Murayama T, Naito Y, Nakachi K, Nakamura M, Nakayama T, Neaton J, Nietert PJ, Nishimoto Y, Norton R, Nozaki A, Ohkubo T, Okayama A, Pan WH, Puska P, Qizilbash N, Reunanen A, Rimm E, Rodgers A, Saitoh S, Sakata K, Sato S, Schnohr P, Schulte H, Selmer R, Sharp D, Shifu X, Shimamoto K, Shipley M, Silbershatz H, Sorlie P, Sritara P, Suh I, Sutherland SE, Sweetnam P, Tamakoshi A, Tanaka H, Thomsen T, Tominaga S, Tomita M, Törnberg S, Tunstall-Pedoe H, Tverdal A, Ueshima H, Vartiainen E, Wald N, Wannamethee SG, Welborn TA, Whincup P, Whitlock G, Willett W, Woo J, Wu ZL, Yao SX, Yarnell J, Yokoyama T, Yoshiike N, Zhang XH. Sex-specific relevance of diabetes to occlusive vascular and other mortality: a collaborative meta-analysis of individual data from 980 793 adults from 68 prospective studies. Lancet Diabetes Endocrinol 2018; 6:538-546. [PMID: 29752194 PMCID: PMC6008496 DOI: 10.1016/s2213-8587(18)30079-2] [Citation(s) in RCA: 148] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Academic Contribution Register] [Received: 11/15/2017] [Revised: 02/20/2018] [Accepted: 02/26/2018] [Indexed: 01/06/2023]
Abstract
BACKGROUND Several studies have shown that diabetes confers a higher relative risk of vascular mortality among women than among men, but whether this increased relative risk in women exists across age groups and within defined levels of other risk factors is uncertain. We aimed to determine whether differences in established risk factors, such as blood pressure, BMI, smoking, and cholesterol, explain the higher relative risks of vascular mortality among women than among men. METHODS In our meta-analysis, we obtained individual participant-level data from studies included in the Prospective Studies Collaboration and the Asia Pacific Cohort Studies Collaboration that had obtained baseline information on age, sex, diabetes, total cholesterol, blood pressure, tobacco use, height, and weight. Data on causes of death were obtained from medical death certificates. We used Cox regression models to assess the relevance of diabetes (any type) to occlusive vascular mortality (ischaemic heart disease, ischaemic stroke, or other atherosclerotic deaths) by age, sex, and other major vascular risk factors, and to assess whether the associations of blood pressure, total cholesterol, and body-mass index (BMI) to occlusive vascular mortality are modified by diabetes. RESULTS Individual participant-level data were analysed from 980 793 adults. During 9·8 million person-years of follow-up, among participants aged between 35 and 89 years, 19 686 (25·6%) of 76 965 deaths were attributed to occlusive vascular disease. After controlling for major vascular risk factors, diabetes roughly doubled occlusive vascular mortality risk among men (death rate ratio [RR] 2·10, 95% CI 1·97-2·24) and tripled risk among women (3·00, 2·71-3·33; χ2 test for heterogeneity p<0·0001). For both sexes combined, the occlusive vascular death RRs were higher in younger individuals (aged 35-59 years: 2·60, 2·30-2·94) than in older individuals (aged 70-89 years: 2·01, 1·85-2·19; p=0·0001 for trend across age groups), and, across age groups, the death RRs were higher among women than among men. Therefore, women aged 35-59 years had the highest death RR across all age and sex groups (5·55, 4·15-7·44). However, since underlying confounder-adjusted occlusive vascular mortality rates at any age were higher in men than in women, the adjusted absolute excess occlusive vascular mortality associated with diabetes was similar for men and women. At ages 35-59 years, the excess absolute risk was 0·05% (95% CI 0·03-0·07) per year in women compared with 0·08% (0·05-0·10) per year in men; the corresponding excess at ages 70-89 years was 1·08% (0·84-1·32) per year in women and 0·91% (0·77-1·05) per year in men. Total cholesterol, blood pressure, and BMI each showed continuous log-linear associations with occlusive vascular mortality that were similar among individuals with and without diabetes across both sexes. INTERPRETATION Independent of other major vascular risk factors, diabetes substantially increased vascular risk in both men and women. Lifestyle changes to reduce smoking and obesity and use of cost-effective drugs that target major vascular risks (eg, statins and antihypertensive drugs) are important in both men and women with diabetes, but might not reduce the relative excess risk of occlusive vascular disease in women with diabetes, which remains unexplained. FUNDING UK Medical Research Council, British Heart Foundation, Cancer Research UK, European Union BIOMED programme, and National Institute on Aging (US National Institutes of Health).
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Abstract
Measurements of radon-222 in seawater suggest the following. The radium-226 content of surface water in both the Atlantic and Pacific oceans is uniformly close to about 4 x 10(-14) gram per liter. The deep Pacific has a concentration of radium-226 that is four times higher and the deep Atlantic a concentration twice as high as that of the surface. These distribution profiles can be explained by the same particle-settling rate for radium-226 from surface to depth for the two oceans and by a threefold longer residence time of water in the deep Pacific than in the deep Atlantic. The vertical distribution of the deficiency of radon-222 in the surface water of the northwest Pacific Ocean suggests a coefficient of vertical eddy diffusion as high as 120 square centimeters per second and a gas-exchange rate for carbon dioxide in surface water between 14 and 60 moles per square meter per year. Vertical profiles of the excess of radon-222 in near-bottom water of the South Atlantic give coefficients of vertical eddy diffusion ranging from 1.5 to more than 50 square centimeters per second.
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Abstract
The amounts and types of nutrients in the environment influence the development and final bacterial and chemical composition of biofilms. In oligotrophic environments, organisms respond to nutrient stress by alterations in their cell morphology and cell surfaces, which enhance adherence. Little is known of the responses to stress by bacteria in the animal oral cavity. The environment in the oral cavity is less extreme, and saliva provides a constant source of nutrients. Catabolic cooperation among oral bacteria allow carbon and nitrogen from salivary glycoproteins to be utilized. Modification of growth environments of oral bacteria can influence their cell surfaces and adhesion. Studies in experimental animals have shown that feeding either glucose or sucrose diets or fasting has little effect on the initial stages of development of oral biofilms. However, diet can influence the proportions of different bacterial species later in biofilm development. Studies of competition among populations in communities of oral bacteria in vitro and in vivo have shown the significance of carbon limitation and excess and changes in environmental pH. Relatively few studies have been made of the role of a nitrogen metabolism in bacterial competition in biofilms. In keeping with biofilms in nature, oral biofilms provide a sequestered habitat, where organisms are protected from removal by saliva and where interactions among cells generate a biofilm environment, distinct from that of saliva. Oral biofilms are an essential component in the etiologies of caries and periodontal disease, and understanding the biology of oral biofilms has aided and will continue to aid in the prevention and treatment of these diseases.
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Review |
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Dai ZQ, Wang R, Ling SK, Wan YM, Li YH. Simulated microgravity inhibits the proliferation and osteogenesis of rat bone marrow mesenchymal stem cells. Cell Prolif 2007; 40:671-84. [PMID: 17877609 PMCID: PMC6496371 DOI: 10.1111/j.1365-2184.2007.00461.x] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 12/21/2022] Open
Abstract
OBJECTIVES Microgravity is known to affect the differentiation of bone marrow mesenchymal stem cells (BMSCs). However, a few controversial findings have recently been reported with respect to the effects of microgravity on BMSC proliferation. Thus, we investigated the effects of simulated microgravity on rat BMSC (rBMSC) proliferation and their osteogeneic potential. MATERIALS AND METHODS rBMSCs isolated from marrow using our established effective method, based on erythrocyte lysis, were identified by their surface markers and their proliferation characteristics under normal conditions. Then, they were cultured in a clinostat to simulate microgravity, with or without growth factors, and in osteogenic medium. Subsequently, proliferation and cell cycle parameters were assessed using methylene blue staining and flow cytometry, respectively; gene expression was determined using Western blotting and microarray analysis. RESULTS Simulated microgravity inhibited population growth of the rBMSCs, cells being arrested in the G(0)/G(1) phase of cell cycle. Growth factors, such as insulin-like growth factor-I, epidermal growth factor and basic fibroblastic growth factor, markedly stimulated rBMSC proliferation in normal gravity, but had only a slight effect in simulated microgravity. Akt and extracellular signal-related kinase 1/2 phosphorylation levels and the expression of core-binding factor alpha1 decreased after 3 days of clinorotation culture. Microarray and gene ontology analyses further confirmed that rBMSC proliferation and osteogenesis decreased under simulated microgravity. CONCLUSIONS The above data suggest that simulated microgravity inhibits population growth of rBMSCs and their differentiation towards osteoblasts. These changes may be responsible for some of the physiological changes noted during spaceflight.
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Research Support, Non-U.S. Gov't |
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Li YH, Teitel S. Finite-size scaling study of the three-dimensional classical XY model. PHYSICAL REVIEW. B, CONDENSED MATTER 1989; 40:9122-9125. [PMID: 9991399 DOI: 10.1103/physrevb.40.9122] [Citation(s) in RCA: 88] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Academic Contribution Register] [Indexed: 11/07/2022]
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Zhang Z, Ran MS, Li YH, Ou GJ, Gong RR, Li RH, Fan M, Jiang Z, Fang DZ. Prevalence of post-traumatic stress disorder among adolescents after the Wenchuan earthquake in China. Psychol Med 2012; 42:1687-1693. [PMID: 22152150 DOI: 10.1017/s0033291711002844] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Academic Contribution Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND The Wenchuan earthquake was a catastrophic earthquake in China. The aim of this study is to explore longitudinally the rates of post-traumatic stress disorder (PTSD) and depression in adolescents after the Wenchuan earthquake, and to identify independent predictors of PTSD. METHOD PTSD and depression symptoms among adolescents at 6, 12 and 18 months after the Wenchuan earthquake were investigated using the PTSD Checklist Civilian Version and the Beck Depression Inventory (BDI). Subjects in this study included 548 high school student survivors in a local boarding high school. RESULTS The rates of PTSD symptoms were 9.7%, 1.3% and 1.6% at the 6-, 12- and 18-month follow-ups, respectively. BDI scores were found to be the best predictor of severity of PTSD at 6, 12 and 18 months. Gender was another variable contributing significantly to PTSD at 6 and 12 months after the earthquake. In the 12-month follow-up, home damage was found to be a predictor of severity of PTSD symptoms. Being a child with siblings was found to be a predictor of severity of PTSD symptoms at 12 and 18 months after the earthquake. CONCLUSIONS PTSD symptoms changed gradually at various stages after the earthquake. Depression symptoms were predictive of PTSD symptoms in the 18-month follow-up study. Other predictors of PTSD symptoms included female gender and being a child with siblings. The results of this study may be helpful for further mental health interventions for adolescents after earthquakes.
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Hanna MN, Ferguson RJ, Li YH, Cvitkovitch DG. uvrA is an acid-inducible gene involved in the adaptive response to low pH in Streptococcus mutans. J Bacteriol 2001; 183:5964-73. [PMID: 11566996 PMCID: PMC99675 DOI: 10.1128/jb.183.20.5964-5973.2001] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 11/20/2022] Open
Abstract
The pH-inducible acid tolerance response (ATR) is believed to play a major role in acid adaptation and virulence of Streptococcus mutans. To study this phenomenon in S. mutans JH1005, differential display PCR was used to identify and clone 13 cDNA products that had increased expression in response to pH 5.0 compared to that of pH 7.5-grown cells. One of these products, confirmed to be pH inducible by RNA dot blot and reverse transcription-PCR analyses, had 67% identity to a uvrA-UV repair excinuclease gene in Bacillus subtilis. Further sequence analysis of the uvrA homologue using the S. mutans genome database revealed that the complete gene was encoded in an open reading frame (ORF) of 2,829 bp (944 amino acids; 104.67 kDa). Immediately 3' of uvrA was an ORF encoding a putative aminopeptidase gene (pepP). uvrA knockouts were constructed in S. mutans strains JH1005, NG8, and UA159 using allelic-exchange mutagenesis, replacing the entire gene with an erythromycin resistance cassette. As with uvrA mutants in other bacteria, the S. mutans uvrA mutants were extremely sensitive to UV irradiation. The uvrA mutant of S. mutans JH1005 was also more sensitive than the wild type to growth at pH 5.0, showing a 15% reduction in growth rate and a 14% reduction in final resting culture density. Acid-adapted S. mutans JH1005 uvrA mutants were shown to be more resistant to UV irradiation than was the parent but were unable to survive exposure to a killing pH of 3.0. Moreover, agarose gel electrophoretic analysis of chromosomal DNA isolated from uvrA-deficient cells exposed to low pH demonstrated more DNA damage than that for the wild-type strain. Here we suggest that uvrA and the nucleotide excision repair pathway are involved in the repair of acid-induced DNA damage and are associated with successful adaptation of S. mutans to low pH.
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Rennermalm A, Li YH, Bohaufs L, Jarstrand C, Brauner A, Brennan FR, Flock JI. Antibodies against a truncated Staphylococcus aureus fibronectin-binding protein protect against dissemination of infection in the rat. Vaccine 2001; 19:3376-83. [PMID: 11348701 DOI: 10.1016/s0264-410x(01)00080-9] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 11/18/2022]
Abstract
Staphylococcus aureus bacteraemia (SAB) originating from local infections can lead to severe secondary infections such as endocarditis. The protective effect of antibodies against secondary infections was studied in a rat model, where a local joint infection leads to bacteraemia and endocarditis on damaged aortic valves. In this study, immunizations with a truncated D2-domain of the S. aureus fibronectin-binding protein displayed on a cow-pea mosaic virus (CPMV-D) carrier induced protection against endocarditis (P < 0.05). Opsonization of S. aureus with antibodies raised against CPMV-D stimulated both neutrophil activity and macrophage phagocytosis in vitro. Furthermore, intravenous administration of these antibodies protected mice from weight loss due to SAB.
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Research Support, Non-U.S. Gov't |
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Lam WK, Leong JCY, Li YH, Hu Y, Lu WW. Biomechanical and electromyographic evaluation of ankle foot orthosis and dynamic ankle foot orthosis in spastic cerebral palsy. Gait Posture 2005; 22:189-97. [PMID: 16214658 DOI: 10.1016/j.gaitpost.2004.09.011] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Academic Contribution Register] [Received: 05/12/2004] [Revised: 07/22/2004] [Accepted: 09/16/2004] [Indexed: 02/02/2023]
Abstract
This study evaluated the biomechanical and electromyographic effects of conventional ankle foot orthoses (AFOs) and dynamic ankle foot orthoses (DAFOs) on gait in patients with spastic cerebral palsy (CP). Thirteen patients with dynamic equinus underwent motion analysis with electromyography. Both AFOs and DAFOs provided longer stride length, permitted pre-positioning for initial contact, and successfully controlled the excessive plantarflexion during the swing phase. Median frequency (MF) of EMG signal indicated that extremely high firing was found in the patient's lower limbs compared to controls that resulted in tiredness. The DAFOs allowed a significantly larger total ankle range of motion than the AFOs. However, AFOs significantly reduced the MF while DAFOs did not. The reduced MF seen when wearing AFOs suggested an improvement of walking endurance. The DAFO had the advantage of less restriction on ankle movement, which avoids muscular atrophy and improves orthotic compliance.
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Fan J, Shek PN, Suntres ZE, Li YH, Oreopoulos GD, Rotstein OD. Liposomal antioxidants provide prolonged protection against acute respiratory distress syndrome. Surgery 2000; 128:332-8. [PMID: 10923013 DOI: 10.1067/msy.2000.108060] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 11/22/2022]
Abstract
BACKGROUND We have previously shown that N-acetylcysteine (NAC), an antioxidant, in the resuscitation fluid after shock prevents lung injury in response to lipopolysaccharide (LPS) by inhibiting chemokine generation by alveolar macrophages in the lung. However, the protection was short-lived. We hypothesized that liposomal (Lip) NAC delivered intratracheally might be delivered directly to the target cells and exert prolonged effect. METHODS Sprague-Dawley rats were bled to a blood pressure of 40 mm Hg for 1 hour and resuscitated with shed blood and equal volume of Ringer's lactate. In some studies 500 mg/kg NAC was included in the resuscitation fluid. Thirty minutes later, 150 microl LipNAC (9.4 mg/kg NAC) was given intratracheally. One hour and 18 hours after resuscitation, LPS (30 microg/kg) or saline was given intratracheally. Lung injury was assessed by permeability to (125)I-albumin, bronchoalveolar lavage neutrophils and lung myeloperoxidase. The cytokine-induced neutrophil chemoattractant (CINC) expression in the lung was assessed by Northern blot. RESULTS At the early time point, both NAC and LipNAC protected the lung with the effects in significantly reducing the increases in transpulmonary albumin flux, neutrophil influx and myeloperoxidase in the lungs of shock/LPS rats. However, by the late time point, only LipNAC retained its salutary effect. This correlated well with persistent ability to prevent CINC increase. In addition, Lipalpha-tocopherol (alpha-T) and LipNAC/alpha-T were tested and determined to be effective to protect the lung. CONCLUSIONS Liposomal encapsulation of antioxidants at low dose provides long lasting protection against acute respiratory distress syndrome after shock. This may represent a novel treatment approach.
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Abstract
Previous studies have shown that Streptococcus mutans NG8 possesses an endogenous surface protein-releasing enzyme (SPRE) activity that liberates its own surface proteins (S. F. Lee, Infect. Immun. 60:4032-4039, 1992). The present study was initiated to investigate the possible role of the release of surface proteins by SPRE in the detachment of biofilm cells in vitro. Initially, the characteristics of surface protein release by the strain (S. mutans BM71) used in this study were shown to be the same as those previously described for S. mutans NG8. BM71 displayed characteristics identical to those of NG8 in terms of pH optima and inhibitor sensitivity for protein release. Monolayer biofilms of S. mutans BM71 were formed on hydroxylapatite rods in a modified chemostat. Detachment of the biofilm cells was measured by viable cell counts of bacteria liberated after incubation of the biofilms in buffers. Results showed that biofilm cells were detached in a pH- dependent manner with a maximum rate of pH 5 (P = 0.016) to 6 (P = 0.002), a range similar to that for optimal surface protein release. The detachment of the biofilm cells was found to be inhibited by ZnCl2 (P = 0.002 to 0.023), which also inhibited surface protein release. Detachment was not inhibited significantly by CaCl2 (P = 0.525 to 0.784), precluding an ionic effect on inhibition by ZnCl2. The extent of detachment could be increased (P = 0.046) by the addition of an SPRE preparation from S. mutans but not heat-inactivated SPRE (P = 0.665) or SPRE in the presence of ZnCl2 (P = 0.199). Detachment was also studied by using biofilms of resting (viable but not dividing) cells. Results similar to those for biofilms formed from growing cells were obtained, indicating that cells detached from biofilms were not daughter cells. The results presented above show that monolayer biofilm cells of S. mutans under conditions of minimal shear force have the ability to detach from a surface and suggest that this detachment was mediated by an endogenous SPRE activity.
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Luo HY, Li YH, Wang W, Wang ZQ, Yuan X, Ma D, Wang FH, Zhang DS, Lin DR, Lin YC, Jia J, Hu XH, Peng JW, Xu RH. Single-agent capecitabine as maintenance therapy after induction of XELOX (or FOLFOX) in first-line treatment of metastatic colorectal cancer: randomized clinical trial of efficacy and safety. Ann Oncol 2016; 27:1074-1081. [PMID: 26940686 DOI: 10.1093/annonc/mdw101] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Received: 01/26/2016] [Accepted: 02/17/2016] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND The optimal strategy of maintenance therapy for patients with mCRC is controversial. This study was to evaluate the efficacy and safety of maintenance therapy with capecitabine versus observation following inductive chemotherapy in patients with metastatic colorectal cancer. PATIENTS AND METHODS In this randomized, open-label, multicenter, phase III trial, patients who received 18-24 weeks of induction chemotherapy with XELOX or FOLFOX and achieved disease control were randomly assigned centrally (1:1) to receive maintenance therapy of capecitabine or only observation until disease progression. The primary end point was progression-free survival (PFS) from randomization; the secondary end points included overall survival (OS), PFS from induction treatment (PFS2) and safety. Analyses were done by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT02027363. RESULTS Between 30 July 2010 and 15 September 2013, 274 patients were enrolled in the study from 11 sites in China and randomly assigned to maintenance group (n = 136) or observation group (n = 138). Clinicopathological characteristics were balanced in two groups. The median follow-up time from randomization was 29.0 months [interquartile range (IQR) 21-36 months]. The primary end point of PFS was statistically significantly longer in capecitabine maintenance group than in observation group {6.43 [95% confidence interval (CI) 5.26-7.71] versus 3.43 (2.83-4.16) months, HR 0.54 (0.42-0.70), P < 0.001}. The median OS of capecitabine maintenance group was longer than that of observation group, but not statistically significant [25.63 (22.46-27.80) versus 23.30 (19.68-26.92) months; HR 0.85 (0.64-1.11), P = 0.2247]. Similar safety profiles were observed in both arms. The most common grade 3 or 4 toxicities in capecitabine maintenance group versus observation group were neutropenia, hand-foot syndrome, and mucositis. CONCLUSIONS Maintenance therapy with a single agent of capecitabine can be considered an appropriate option following the induction of XELOX or FOLFOX in mCRC patients with acceptable toxicities. CLINICAL TRIALS NUMBER NCT02027363.
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Clinical Trial, Phase III |
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Gao XN, Yan F, Lin J, Gao L, Lu XL, Wei SC, Shen N, Pang JX, Ning QY, Komeno Y, Deng AL, Xu YH, Shi JL, Li YH, Zhang DE, Nervi C, Liu SJ, Yu L. AML1/ETO cooperates with HIF1α to promote leukemogenesis through DNMT3a transactivation. Leukemia 2015; 29:1730-40. [PMID: 25727291 DOI: 10.1038/leu.2015.56] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Received: 08/14/2014] [Revised: 02/16/2015] [Accepted: 02/23/2015] [Indexed: 12/27/2022]
Abstract
The mechanisms by which AML1/ETO (A/E) fusion protein induces leukemogenesis in acute myeloid leukemia (AML) without mutagenic events remain elusive. Here we show that interactions between A/E and hypoxia-inducible factor 1α (HIF1α) are sufficient to prime leukemia cells for subsequent aggressive growth. In agreement with this, HIF1α is highly expressed in A/E-positive AML patients and strongly predicts inferior outcomes, regardless of gene mutations. Co-expression of A/E and HIF1α in leukemia cells causes a higher cell proliferation rate in vitro and more serious leukemic status in mice. Mechanistically, A/E and HIF1α form a positive regulatory circuit and cooperate to transactivate DNMT3a gene leading to DNA hypermethylation. Pharmacological or genetic interventions in the A/E-HIF1α loop results in DNA hypomethylation, a re-expression of hypermethylated tumor-suppressor p15(INK4b) and the blockage of leukemia growth. Thus high HIF1α expression serves as a reliable marker, which identifies patients with a poor prognosis in an otherwise prognostically favorable AML group and represents an innovative therapeutic target in high-risk A/E-driven leukemia.
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Research Support, Non-U.S. Gov't |
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Abstract
We have developed a modified Boyden chamber system for assessing tumor cell transmigration across endothelial monolayer in vitro. This radiometric-based method allows us to take into account the cells which have traversed but detached from the filter, a significant fraction not included in the existing method of visual counting. The method was applied to examine six malignant and one non-malignant cell lines. The variable invasive potentials of these cells were found to correlate with their ability to disrupt the endothelial cell monolayers.
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Yamahara J, Huang QR, Li YH, Xu L, Fujimura H. Gastrointestinal motility enhancing effect of ginger and its active constituents. Chem Pharm Bull (Tokyo) 1990; 38:430-1. [PMID: 2337957 DOI: 10.1248/cpb.38.430] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 12/31/2022]
Abstract
The effect of ginger root (Zingiberis Rhizoma) on gastrointestinal motility was examined based on its ability to enhance charcoal meal transport in mice. Oral administrations of the acetone extract of ginger (which contains volatile oils and bitter substances) at 75 mg/kg, [6]-shogaol at 2.5 mg/kg, or a [6]-, [8]- or [10]-gingerol at 5 mg/kg enhanced the transport of a charcoal meal. The effects of these substances were similar to or slightly weaker than those of metoclopramide and donperidone.
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Fan J, Kapus A, Li YH, Rizoli S, Marshall JC, Rotstein OD. Priming for enhanced alveolar fibrin deposition after hemorrhagic shock: role of tumor necrosis factor. Am J Respir Cell Mol Biol 2000; 22:412-21. [PMID: 10745022 DOI: 10.1165/ajrcmb.22.4.3857] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 11/24/2022] Open
Abstract
Hemorrhagic shock due to major trauma predisposes to the development of acute respiratory distress syndrome. Because lung fibrin deposition is one of the hallmarks of this syndrome, we hypothesized that resuscitated shock might predispose to the development of a net procoagulant state in the lung. A rodent model of shock/resuscitation followed by low-dose intratracheal lipopolysaccharide (LPS), a clinically relevant "two-hit" model, was used to test this hypothesis. Resuscitated shock primed the lungs for an increased tissue factor and plasminogen activator (PA) inhibitor-1 gene expression in response to LPS, while the fibrinolytic PA was reduced. These alterations were recapitulated in isolated alveolar macrophages, suggesting their role in the process. LPS-induced tumor necrosis factor (TNF) was also augmented in animals after antecedent shock/resuscitation, and studies using anti-TNF antibodies revealed that TNF expression was critical to the induction of the procoagulant molecules and the reduction in PA. By contrast, TNF did not appear to play an important role in neutrophil sequestration in this model, inasmuch as anti-TNF had no effect on lung neutrophil accumulation or chemokine expression. However, treatment prevented albumin leak by preventing alveolar neutrophil activation. The inclusion of the antioxidant N-acetyl-cysteine in the resuscitation fluid resulted in prevention of both the development of the net procoagulant state and lung neutrophil sequestration, suggesting a role for upstream oxidant effects in the priming process. These studies provide a cellular and molecular basis for lung fibrin deposition after resuscitated shock and demonstrate a divergence of pathways responsible for fibrin generation and neutrophil accumulation.
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Liljequist R, Haapalinna A, Ahlander M, Li YH, Männistö PT. Catechol O-methyltransferase inhibitor tolcapone has minor influence on performance in experimental memory models in rats. Behav Brain Res 1997; 82:195-202. [PMID: 9030401 DOI: 10.1016/s0166-4328(97)80989-8] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 02/03/2023]
Abstract
Two catechol O-methyltransferase inhibitors, peripherally acting entacapone and also centrally acting tolcapone, were tested regarding their capacity to influence learning and memory in adult intact rats. Tolcapone was also studied in rats treated with scopolamine, in adult rats lesioned in the nuclei basalis magnocellularis, and in aged rats. Spatial working memory performance (radial-arm maze) of intact rats was facilitated following pretraining i.p. administration of tolcapone (10 mg/kg). Entacapone was ineffective at doses of 10 and 30 mg/kg. Senescent poor performers improved their accomplishment in the spatial memory task (linear-arm maze) under the influence of tolcapone. Scopolamine (1 mg/kg) impaired working memory performance. Bilateral lesions in the nucleus basalis magnocellularis reduced choline acetyltransferase activity in the frontal cortex by 26% and retarded the learning rate of spatial place task. Tolcapone was not able to counteract the performance deficits in these models. It is concluded that tolcapone can either slightly improve or impair the memory functions depending on task specific elements and performance factors.
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Li YH, Bowden GH. The effect of environmental pH and fluoride from the substratum on the development of biofilms of selected oral bacteria. J Dent Res 1994; 73:1615-26. [PMID: 7929976 DOI: 10.1177/00220345940730100601] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 01/27/2023] Open
Abstract
The present study was initiated to answer the question, "Does fluoride from the substratum influence the accumulation of bacterial cells in an associated biofilm?" 'Fluoride-bound hydroxyapatite' (FHA) and 'fluoride-free hydroxyapatite' (HA) rods were prepared as test and control surfaces, respectively. Biofilms of S. mutans BM71, A. naeslundii genospecies 2 WVU627, and L. casei BM225 accumulated on the surfaces of rods in a semi-defined, mucin-based medium in a chemostat. Culture conditions were varied from pH 4.5 to 7.0 under carbon (glucose) limitation and excess, at a dilution rate of D = 0.1 h-1. Low environmental pH reduced both the numbers of cells on HA surfaces during the early phases (from 0 to 2 h) of accumulation and the final numbers of cells in mature biofilms (20 h). The initial adherence of cells was unaffected by surface fluoride under any of the conditions tested. Similarly, biofilm cells under carbon limitation and those under carbon excess at pH 7.0 were not affected by surface fluoride. However, at low environmental pH values, pH 5.5 for S. mutans and pH 6.0 for A. naeslundii under glucose excess, the accumulation of biofilm cells on the FHA surfaces was significantly reduced (p < 0.05-0.001). Biofilm cell number doubling times of S. mutans and A. naeslundii were increased on FHA relative to HA. Biofilms of L. casei were not significantly affected, even at pH 4.5 in glucose excess. The results confirmed that fluoride from the substratum affected fluoride-sensitive biofilm cells but only under conditions of glucose excess ad low pH.
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Li YH, Rozanski GJ. Effects of human recombinant interleukin-1 on electrical properties of guinea pig ventricular cells. Cardiovasc Res 1993; 27:525-30. [PMID: 8490954 DOI: 10.1093/cvr/27.3.525] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Academic Contribution Register] [Indexed: 01/31/2023] Open
Abstract
OBJECTIVE To determine whether cytokines alter the electrical properties of heart cells, the effects of human recombinant interleukin-1 beta (IL-1) were examined in excised tissues and dissociated myocytes from guinea pig ventricles. METHODS In a first series of experiments, transmembrane potentials were recorded from isolated papillary muscles superfused with 1 ng.ml-1 IL-1 in the absence and presence of blockers of arachidonic acid metabolism. Secondly, to examine the ionic mechanisms underlying the response to IL-1, ventricular myocytes were dissociated from collagenase perfused hearts and studied using the whole cell configuration of the patch clamp technique under conditions designed to isolate the L-type Ca2+ current (ICa). RESULTS In excised papillary muscles, IL-1 significantly prolonged action potential duration (measured at 90% repolarisation) by 24.2(SEM 2.2) ms and effective refractory period by 22.9(2.3) ms (both p < 0.001; n = 44). Other measured variables were not affected. Treatment of muscles with cyclo-oxygenase inhibitors, indomethacin (1 x 10(-5) M) or acetyl salicylic acid (2 x 10(-4) M), abolished the prolongation of action potential duration elicited by IL-1. However, the effects of IL-1 were also blocked by the lipoxygenase inhibitor nordihydroguaiaretic acid (2 x 10(-5) M) or by treating tissues with the leukotriene receptor blocker, ICI198615 (1 x 10(-8) M). In isolated myocytes, 1 ng.ml-1 IL-1 increased ICa density in 44 of 78 cells by 33.6(7.5)% [11.7(0.6) v 14.6(0.7) pA.pF-1; p < 0.001] during voltage steps from -40 to 0 mV. CONCLUSIONS IL-1 modifies electrical properties of cardiac cells via lipid second messengers generated by cyclo-oxygenase and lipoxygenase pathways. Voltage clamp analyses suggest that these effects are mediated, at least in part, by changes in the conductance of calcium channels.
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Li YH, Ho TL. Superfluid 3He in very confined regular geometries. PHYSICAL REVIEW. B, CONDENSED MATTER 1988; 38:2362-2370. [PMID: 9946539 DOI: 10.1103/physrevb.38.2362] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Academic Contribution Register] [Indexed: 11/07/2022]
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Li YH, Brauner A, Jonsson B, van der Ploeg I, Söder O, Holst M, Jensen JS, Lagercrantz H, Tullus K. Ureaplasma urealyticum-induced production of proinflammatory cytokines by macrophages. Pediatr Res 2000; 48:114-9. [PMID: 10879809 DOI: 10.1203/00006450-200007000-00020] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Academic Contribution Register] [Indexed: 11/06/2022]
Abstract
Ureaplasma urealyticum is relatively common in the respiratory tract of very low birth weight infants and has been hypothesized to be involved in the development of chronic lung disease. The purpose of this study was to investigate whether U. urealyticum could stimulate macrophages to produce proinflammatory cytokines in vitro, which are early pathologic changes in the lung during the development of chronic lung disease. A human monocytic cell line (THP-1) differentiated to macrophages, a rat alveolar macrophage cell line (Nr8383), and human lung macrophages from tracheobronchial aspirate fluid in preterm infants were exposed to U. urealyticum antigen for 24 h. The protein levels of human IL-6, tumor necrosis factor-alpha (TNF-alpha), and rat TNF-alpha were measured with ELISA. Rat IL-6 was analyzed with a specific bioassay. The mRNA levels of these cytokines were detected by reverse transcriptase-PCR. The production of TNF-alpha and IL-6 increased after stimulation with U. urealyticum in both the human and rat macrophage cell lines. In tracheobronchial aspirate fluid macrophages, U. urealyticum increased the production of TNF-alpha from 14 to 84% and IL-6 from 46 to 268% above control levels. U. urealyticum also induced gene expression of TNF-alpha and IL-6. In conclusion, U. urealyticum could be an important factor in the development of chronic lung disease because of its ability to induce alveolar macrophage proinflammatory cytokine production.
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