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Berman HM, Westbrook J, Feng Z, Gilliland G, Bhat TN, Weissig H, Shindyalov IN, Bourne PE. The Protein Data Bank. Nucleic Acids Res 2000; 28:235-42. [PMID: 10592235 PMCID: PMC102472 DOI: 10.1093/nar/28.1.235] [Citation(s) in RCA: 26752] [Impact Index Per Article: 1070.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/1999] [Revised: 10/17/1999] [Accepted: 10/17/1999] [Indexed: 11/14/2022] Open
Abstract
The Protein Data Bank (PDB; http://www.rcsb.org/pdb/ ) is the single worldwide archive of structural data of biological macromolecules. This paper describes the goals of the PDB, the systems in place for data deposition and access, how to obtain further information, and near-term plans for the future development of the resource.
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26752 |
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Pepe MS, Etzioni R, Feng Z, Potter JD, Thompson ML, Thornquist M, Winget M, Yasui Y. Phases of biomarker development for early detection of cancer. J Natl Cancer Inst 2001; 93:1054-61. [PMID: 11459866 DOI: 10.1093/jnci/93.14.1054] [Citation(s) in RCA: 1130] [Impact Index Per Article: 47.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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Review |
24 |
1130 |
3
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Stanford JL, Feng Z, Hamilton AS, Gilliland FD, Stephenson RA, Eley JW, Albertsen PC, Harlan LC, Potosky AL. Urinary and sexual function after radical prostatectomy for clinically localized prostate cancer: the Prostate Cancer Outcomes Study. JAMA 2000; 283:354-60. [PMID: 10647798 DOI: 10.1001/jama.283.3.354] [Citation(s) in RCA: 810] [Impact Index Per Article: 32.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
CONTEXT Patients with prostate cancer and their physicians need knowledge of treatment options and their potential complications, but limited data on complications are available in unselected population-based cohorts of patients. OBJECTIVE To measure changes in urinary and sexual function in men who have undergone radical prostatectomy for clinically localized prostate cancer. DESIGN The Prostate Cancer Outcomes Study, a population-based longitudinal cohort study with up to 24 months of follow-up. SETTING Population-based cancer registries in 6 geographic regions of the United States. PARTICIPANTS A total of 1291 black, white, and Hispanic men aged 39 to 79 years who were diagnosed as having primary prostate cancer between October 1, 1994, and October 31, 1995, and who underwent radical prostatectomy within 6 months of diagnosis for clinically localized disease. MAIN OUTCOME MEASURES Distribution of and change in urinary and sexual function measures reported by patients at baseline and 6, 12, and 24 months after diagnosis. RESULTS At 18 or more months following radical prostatectomy, 8.4% of men were incontinent and 59.9% were impotent. Among men who were potent before surgery, the proportion of men reporting impotence at 18 or more months after surgery varied according to whether the procedure was nerve sparing (65.6% of non-nerve-sparing, 58.6% of unilateral, and 56.0% of bilateral nerve-sparing). At 18 or more months after surgery, 41.9% reported that their sexual performance was a moderate-to-large problem. Both sexual and urinary function varied by age (39.0% of men aged <60 years vs 15.3 %-21.7% of older men were potent at > or =18 months [P<.001]; 13.8% of men aged 75-79 years vs 0.7%-3.6% of younger men experienced the highest level of incontinence at > or =18 months [P = .03]), and sexual function also varied by race (38.4% of black men reported firm erections at > or =18 months vs 25.9% of Hispanic and 21.3% of white men; P = .001). CONCLUSIONS Our study suggests that radical prostatectomy is associated with significant erectile dysfunction and some decline in urinary function. These results may be particularly helpful to community-based physicians and their patients with prostate cancer who face difficult treatment decisions.
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Multicenter Study |
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Abstract
The p53 pathway is composed of hundreds of genes and their products that respond to a wide variety of stress signals. These responses to stress include apoptosis, cellular senescence or cell cycle arrest. In addition the p53-regulated genes produce proteins that communicate these stress signals to adjacent cells, prevent and repair damaged DNA and create feedback loops that enhance or attenuate p53 activity and communicate with other signal transduction pathways. Many questions remain to be explored in our understanding of how this network of genes plays a role in protection from cancers, therapy and integrating the homeostatic mechanisms of stress management and fidelity in a cell and organism. The goal of this chapter is to elucidate some of those questions and suggest new directions for this area of research.
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Review |
18 |
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Berman HM, Bhat TN, Bourne PE, Feng Z, Gilliland G, Weissig H, Westbrook J. The Protein Data Bank and the challenge of structural genomics. NATURE STRUCTURAL BIOLOGY 2000; 7 Suppl:957-9. [PMID: 11103999 DOI: 10.1038/80734] [Citation(s) in RCA: 391] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The PDB has created systems for the processing, exchange, query, and distribution of data that will enable many aspects of high throughput structural genomics.
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391 |
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Huang B, Zhao J, Unkeless JC, Feng ZH, Xiong H. TLR signaling by tumor and immune cells: a double-edged sword. Oncogene 2008; 27:218-24. [PMID: 18176603 DOI: 10.1038/sj.onc.1210904] [Citation(s) in RCA: 287] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The tumor cell signaling pathways that trigger the uncontrolled proliferation, resistance to apoptosis, metastasis and escape from immune surveillance are partially understood. Toll-like receptors (TLRs), which recognize a variety of pathogen-associated molecular patterns, are centrally involved in the initiation of the innate and adaptive immune responses. However, recent evidence shows that functional TLRs are also expressed on a wide variety of tumors suggesting that TLRs may play important roles in tumor biology. Activation of tumor cell TLRs not only promotes tumor cell proliferation and resistance to apoptosis, but also enhances tumor cell invasion and metastasis by regulating metalloproteinases and integrins. Moreover, the activation of TLR signaling in tumor cells induces the synthesis of proinflammatory factors and immunosuppressive molecules, which enhance the resistance of tumor cells to cytotoxic lymphocyte attack and lead to immune evasion. Thus, the neoplastic process may usurp TLR signaling pathways to advance cancer progression, which suggests that targeting tumor TLR signaling pathways may open novel therapeutic avenues.
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Review |
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287 |
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Abstract
In common forms of obesity, hyperphagia, hyperinsulinemia, and hyperleptinemia coexist. Here, we demonstrate rapid induction of insulin and leptin resistance by short-term overfeeding. After 3 and 7 days on the assigned diet regimen, rats were tested for their biological responses to acute elevations in plasma insulin and leptin concentrations. Severe resistance to the metabolic effects of both leptin and insulin ensued after just 3 days of overfeeding. During the insulin clamp studies, glucose production was decreased by approximately 70% in control rats and 28-53% in overfed rats. Similarly, leptin infusion doubled the contribution of gluconeogenesis to glucose output in control rats but failed to modify gluconeogenesis in overfed animals. These findings demonstrate a paradoxical and rapid collapse of the leptin system in response to nutrient excess. This partial failure is tightly coupled with the onset of insulin resistance.
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Feng Z, Velasco-Hernández JX. Competitive exclusion in a vector-host model for the dengue fever. J Math Biol 1997; 35:523-44. [PMID: 9145954 DOI: 10.1007/s002850050064] [Citation(s) in RCA: 238] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We study a system of differential equations that models the population dynamics of an SIR vector transmitted disease with two pathogen strains. This model arose from our study of the population dynamics of dengue fever. The dengue virus presents four serotypes each induces host immunity but only certain degree of cross-immunity to heterologous serotypes. Our model has been constructed to study both the epidemiological trends of the disease and conditions that permit coexistence in competing strains. Dengue is in the Americas an epidemic disease and our model reproduces this kind of dynamics. We consider two viral strains and temporary cross-immunity. Our analysis shows the existence of an unstable endemic state ('saddle' point) that produces a long transient behavior where both dengue serotypes cocirculate. Conditions for asymptotic stability of equilibria are discussed supported by numerical simulations. We argue that the existence of competitive exclusion in this system is product of the interplay between the host superinfection process and frequency-dependent (vector to host) contact rates.
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Ross AG, Sleigh AC, Li Y, Davis GM, Williams GM, Jiang Z, Feng Z, McManus DP. Schistosomiasis in the People's Republic of China: prospects and challenges for the 21st century. Clin Microbiol Rev 2001; 14:270-95. [PMID: 11292639 PMCID: PMC88974 DOI: 10.1128/cmr.14.2.270-295.2001] [Citation(s) in RCA: 238] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Schistosomiasis japonica is a serious communicable disease and a major disease risk for more than 30 million people living in the tropical and subtropical zones of China. Infection remains a major public health concern despite 45 years of intensive control efforts. It is estimated that 865,000 people and 100,250 bovines are today infected in the provinces where the disease is endemic, and its transmission continues. Unlike the other schistosome species known to infect humans, the oriental schistosome, Schistosoma japonicum, is a true zoonotic organism, with a range of mammalian reservoirs, making control efforts extremely difficult. Clinical features of schistosomiasis range from fever, headache, and lethargy to severe fibro-obstructive pathology leading to portal hypertension, ascites, and hepatosplenomegaly, which can cause premature death. Infected children are stunted and have cognitive defects impairing memory and learning ability. Current control programs are heavily based on community chemotherapy with a single dose of the drug praziquantel, but vaccines (for use in bovines and humans) in combination with other control strategies are needed to make elimination of the disease possible. In this article, we provide an overview of the biology, epidemiology, clinical features, and prospects for control of oriental schistosomiasis in the People's Republic of China.
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Review |
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238 |
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Kristal AR, Feng Z, Coates RJ, Oberman A, George V. Associations of race/ethnicity, education, and dietary intervention with the validity and reliability of a food frequency questionnaire: the Women's Health Trial Feasibility Study in Minority Populations. Am J Epidemiol 1997; 146:856-69. [PMID: 9384206 DOI: 10.1093/oxfordjournals.aje.a009203] [Citation(s) in RCA: 225] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
This report describes the associations of race/ethnicity and years of education with the validity, reliability, and bias of a self-administered food frequency questionnaire (FFQ) designed to be sensitive to low-fat, regional, and ethnic dietary patterns. Data were from the Women's Health Trial Feasibility Study in Minority Populations, a randomized clinical trial conducted between 1992 and 1994 to test the feasibility of a low-fat dietary intervention that targeted low-income, black, and Hispanic women. Of 1,015 participants eligible for these analyses, 28.1% were black, 16.2% were Hispanic, and 12.3% had not completed high school. The analyses focused on percentage of energy obtained from fat, and used 4-day food records as the criterion instrument. Validity at baseline, defined as the correlation between FFQs and food records, was lower among blacks than among whites (0.26 vs. 0.49; p < 0.001), did not differ between Hispanics and whites, and was lower among women with fewer years of education (0.19, 0.35, 0.49, and 0.42 for <12, 12, 13-15, and > or =16 years of education, respectively; for trend, p < 0.05). Six months after randomization, validity increased in most race/ethnicity and education subgroups, and differences across groups became small and statistically nonsignificant. Validity increased significantly among participants receiving the dietary intervention, while increases among control women were somewhat smaller. Reliability, defined as the correlation between baseline and 6-month measures among controls, was similar across racial/ethnic and educational groups. Bias at baseline, defined as the mean value from the FFQ minus the mean from the food record, was 4.6 percentage points of energy from fat; it was lowest among blacks (p < 0.01) and did not differ by years of education. These results suggest that special protocols which address participant training may be necessary when using self-administered FFQs in minority or poorly educated populations.
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Clinical Trial |
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225 |
11
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Reid BJ, Blount PL, Feng Z, Levine DS. Optimizing endoscopic biopsy detection of early cancers in Barrett's high-grade dysplasia. Am J Gastroenterol 2000; 95:3089-96. [PMID: 11095322 DOI: 10.1111/j.1572-0241.2000.03182.x] [Citation(s) in RCA: 210] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVE The of high-grade dysplasia management (HGD) in Barrett's esophagus remains controversial, in part, because of uncertainty about the ability of endoscopic biopsies to consistently detect early, curable cancers. METHODS Here we report cancers we have diagnosed in 45 patients with Barrett's HGD using a protocol involving serial endoscopies with four-quadrant biopsies taken at 1-cm intervals. We compare these results to a modeled endoscopic biopsy protocol in which four-quadrant biopsies are taken every 2 cm in the Barrett's segment. RESULTS Thirteen cancers were detected at the baseline endoscopy and 32 in surveillance. In 82% of patients, cancer was detected at a single 1-cm level of the esophagus, and in 69% the cancer was detected in a single endoscopic biopsy specimen. A 2-cm protocol missed 50% of cancers that were detected by a 1-cm protocol in Barrett's segments 2 cm or more without visible lesions. The maximum depth of cancer invasion was intramucosal in 96% of patients. Only 39% of patients who had endoscopic biopsy cancer diagnoses had cancer detected in the esophagectomy specimen. Adverse outcomes included the development of regional metastatic disease during surveillance (1 of 32), operative mortality (3 of 36), including two patients who had their primary surgeries at other institutions, and death from metastatic disease after endoscopic ablation performed at another institution (1 of 3). CONCLUSIONS A four-quadrant, 1-cm endoscopic biopsy protocol performed at closely timed intervals consistently detects early cancers arising in HGD in Barrett's esophagus and should be used in patients with HGD who do not undergo surgical resection.
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Comparative Study |
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210 |
12
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Sorensen G, Thompson B, Glanz K, Feng Z, Kinne S, DiClemente C, Emmons K, Heimendinger J, Probart C, Lichtenstein E. Work site-based cancer prevention: primary results from the Working Well Trial. Am J Public Health 1996; 86:939-47. [PMID: 8669517 PMCID: PMC1380434 DOI: 10.2105/ajph.86.7.939] [Citation(s) in RCA: 165] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
OBJECTIVES This paper presents the behavioral results of the Working Well Trial, the largest US work site cancer prevention and control trial to date. METHODS The Working Well Trial used a randomized, matched-pair evaluation design, with the work site as the unit of assignment and analysis. The study was conducted in 111 work sites (n = 28,000 workers). The effects of the intervention were evaluated by comparing changes in intervention and control work sites, as measured in cross-sectional surveys at baseline and follow-up. The 2-year intervention targeted both individuals and the work-site environment. RESULTS There occurred a net reduction in the percentage of energy obtained from fat consumption of 0.37 percentage points (P = .033), a net increase in fiber densities of 0.13 g/1000 kcal (P = .056), and an average increase in fruit and vegetable intake of 0.18 servings per day (P = .0001). Changes in tobacco use were in the desired direction but were not significant. CONCLUSIONS Significant but small differences were observed for nutrition. Positive trends, but no significant results, were observed in trial-wide smoking outcomes. The observed net differences were small owing to the substantial secular changes in target behaviors.
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Feng Z, Marti A, Jehn B, Altermatt HJ, Chicaiza G, Jaggi R. Glucocorticoid and progesterone inhibit involution and programmed cell death in the mouse mammary gland. J Biophys Biochem Cytol 1995; 131:1095-103. [PMID: 7490285 PMCID: PMC2200011 DOI: 10.1083/jcb.131.4.1095] [Citation(s) in RCA: 162] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Milk production during lactation is a consequence of the suckling stimulus and the presence of glucocorticoids, prolactin, and insulin. After weaning the glucocorticoid hormone level drops, secretory mammary epithelial cells die by programmed cell death and the gland is prepared for a new pregnancy. We studied the role of steroid hormones and prolactin on the mammary gland structure, milk protein synthesis, and on programmed cell death. Slow-release plastic pellets containing individual hormones were implanted into a single mammary gland at lactation. At the same time the pups were removed and the consequences of the release of hormones were investigated histologically and biochemically. We found a local inhibition of involution in the vicinity of deoxycorticosterone- and progesterone-release pellets while prolactin-release pellets were ineffective. Dexamethasone, a very stable and potent glucocorticoid hormone analogue, inhibited involution and programmed cell death in all the mammary glands. It led to an accumulation of milk in the glands and was accompanied by an induction of protein kinase A, AP-1 DNA binding activity and elevated c-fos, junB, and junD mRNA levels. Several potential target genes of AP-1 such as stromelysin-1, c-jun, and SGP-2 that are induced during normal involution were strongly inhibited in dexamethasone-treated animals. Our results suggest that the cross-talk between steroid hormone receptors and AP-1 previously described in cells in culture leads to an impairment of AP-1 activity and to an inhibition of involution in the mammary gland implying that programmed cell death in the postlactational mammary gland depends on functional AP-1.
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research-article |
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Krivtsov AV, Figueroa ME, Sinha AU, Stubbs MC, Feng Z, Valk PJM, Delwel R, Döhner K, Bullinger L, Kung AL, Melnick AM, Armstrong SA. Cell of origin determines clinically relevant subtypes of MLL-rearranged AML. Leukemia 2012; 27:852-60. [PMID: 23235717 DOI: 10.1038/leu.2012.363] [Citation(s) in RCA: 153] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Mixed lineage leukemia (MLL)-fusion proteins can induce acute myeloid leukemias (AMLs) from either hematopoietic stem cells (HSCs) or granulocyte-macrophage progenitors (GMPs), but it remains unclear whether the cell of origin influences the biology of the resultant leukemia. MLL-AF9-transduced single HSCs or GMPs could be continuously replated, but HSC-derived clones were more likely than GMP-derived clones to initiate AML in mice. Leukemia stem cells derived from either HSCs or GMPs had a similar immunophenotype consistent with a maturing myeloid cell (LGMP). Gene expression analyses demonstrated that LGMP inherited gene expression programs from the cell of origin including high-level Evi-1 expression in HSC-derived LGMP. The gene expression signature of LGMP derived from HSCs was enriched in poor prognosis human MLL-rearranged AML in three independent data sets. Moreover, global 5'-mC levels were elevated in HSC-derived leukemias as compared with GMP-derived leukemias. This mirrored a difference seen in 5'-mC between MLL-rearranged human leukemias that are either EVI1 positive or EVI1 negative. Finally, HSC-derived leukemias were more resistant to chemotherapy than GMP-derived leukemias. These data demonstrate that the cell of origin influences the gene expression profile, the epigenetic state and the drug response in AML, and that these differences can account for clinical heterogeneity within a molecularly defined group of leukemias.
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Research Support, Non-U.S. Gov't |
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153 |
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Nan H, Ping Y, Xuan C, Yongxang L, Xiaolan Z, Guangjun C, Zihong Z, Feng Z, Yuanru C, Xianghuai L, Tingfei X. Blood compatibility of amorphous titanium oxide films synthesized by ion beam enhanced deposition. Biomaterials 1998; 19:771-6. [PMID: 9663752 DOI: 10.1016/s0142-9612(98)00212-9] [Citation(s) in RCA: 152] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Titanium oxide films were synthesized on titanium, cobalt alloy and low-temperature isotropic pryolytic carbon by ion beam enhanced deposition. The non-stoichiometrical titanium oxide films were obtained. Blood compatibility of the films were evaluated by clotting time measurement, platelet adhesion investigation and hemolysis analyses. The results revealed that blood compatibility of the materials was improved by the coating of titanium oxide films. Semiconductor nature of non-stoichiometric titanium oxide films might be responsible for the improvement of blood compatibility.
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Jung E, Lenhart S, Feng Z. Optimal control of treatments in a two-strain tuberculosis model. ACTA ACUST UNITED AC 2002. [DOI: 10.3934/dcdsb.2002.2.473] [Citation(s) in RCA: 142] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Abstract
Following primary tuberculosis (TB) infection, only approximately 10% of individuals develop active T.B. Most people are assumed to mount an effective immune response to the initial infection that limits proliferation of the bacilli and leads to long-lasting partial immunity both to further infection and to reactivation of latent bacilli remaining from the original infection. Infected individuals may develop active TB as a consequence of exogenous reinfection, i.e., acquiring a new infection from another infectious individual. Our results in this paper suggest that exogenous reinfection has a drastic effect on the qualitative dynamics of TB. The incorporation of exogenous reinfection into our TB model allows the possibility of a subcritical bifurcation at the critical value of the basic reproductive number R(0)=1, and hence the existence of multiple endemic equilibria for R(0)<1 and the exogenous reinfection rate larger than a threshold. Our results suggest that reducing R(0) to be smaller than one may not be sufficient to eradicate the disease. An additional reduction in reinfection rate may be required. These results may also partially explain the recently observed resurgence of TB.
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Abstract
Over a 5-year period, 232 microvascular composite-tissue transfers to the head and neck, trunk, and extremities were monitored using the laser Doppler flowmeter. Thirteen free flaps (5.6 percent) developed vascular complications, all within 4 days after surgery. The laser Doppler flowmeter detected vascular compromise in all cases with no false positives or negatives. Failure to monitor the flap according to protocol by nursing staff occurred in one patient, which led to a delay in detection of venous compromise and subsequent flap loss. The salvage rate was 69.2 percent, leading to an overall flap viability of 98.3 percent. Our series of free-flap monitoring using the laser Doppler flowmeter is the largest reported to date. Review of the English literature shows consistent support by numerous clinical series for the use of the laser Doppler as a valuable postoperative monitor after free-flap transfers.
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137 |
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Bian X, McAllister-Lucas LM, Shao F, Schumacher KR, Feng Z, Porter AG, Castle VP, Opipari AW. NF-kappa B activation mediates doxorubicin-induced cell death in N-type neuroblastoma cells. J Biol Chem 2001; 276:48921-9. [PMID: 11679590 DOI: 10.1074/jbc.m108674200] [Citation(s) in RCA: 127] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Neuroblastoma is the most common extracranial solid tumor of childhood. N-type neuroblastoma cells (represented by SH-SY5Y and IMR32 cell lines) are characterized by a neuronal phenotype. N-type cell lines are generally N-myc amplified, express the anti-apoptotic protein Bcl-2, and do not express caspase-8. The present study was designed to determine the mechanism by which N-type cells die in response to specific cytotoxic agents (such as cisplatin and doxorubicin) commonly used to treat this disease. We found that N-type cells were equally sensitive to cisplatin and doxorubicin. Yet death induced by cisplatin was inhibited by the nonselective caspase inhibitor z-Val-Ala-Asp-fluoromethylketone or the specific caspase-9 inhibitor N-acetyl-Leu-Glu-His-Asp-aldehyde, whereas in contrast, caspase inhibition did not prevent doxorubicin-induced death. Neither the reactive oxygen species nor the mitochondrial permeability transition appears to play an important role in this process. Doxorubicin induced NF-kappa B transcriptional activation in association with I-kappa B alpha degradation prior to loss of cell viability. Surprisingly, the antioxidant and NF-kappa B inhibitor pyrrolidine dithiocarbamate blocked doxorubicin-induced NF-kappa B transcriptional activation and provided profound protection against doxorubicin killing. Moreover, SH-SY5Y cells expressing a super-repressor form of I-kappa B were completely resistant to doxorubicin killing. Together these findings show that NF-kappa B activation mediates doxorubicin-induced cell death without evidence of caspase function and suggest that cisplatin and doxorubicin engage different death pathways to kill neuroblastoma cells.
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Obici S, Feng Z, Tan J, Liu L, Karkanias G, Rossetti L. Central melanocortin receptors regulate insulin action. J Clin Invest 2001; 108:1079-85. [PMID: 11581309 PMCID: PMC200952 DOI: 10.1172/jci12954] [Citation(s) in RCA: 125] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Energy balance and insulin action are tightly coregulated. Leptin regulates energy intake and expenditure partly by modulation of the melanocortin pathway in the hypothalamus. Here we demonstrate potent effects of the melanocortin pathway on insulin action and body distribution of adiposity. Conscious rats received week-long infusions of either a melanocortin receptor agonist, alpha-melanocyte-stimulating hormone (alpha-MSH), or antagonist, SHU9119, in the third cerebral ventricle while food intake was maintained constant in each group. alpha-MSH decreased intra-abdominal fat and markedly enhanced the actions of insulin on both glucose uptake and production, while SHU9119 exerted opposite effects. Our findings elucidate a neuroendocrine network that is likely to play a central role in the coupling of energy intake and insulin action.
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MESH Headings
- Animals
- Glucose/metabolism
- Hypothalamus/metabolism
- Insulin/metabolism
- Insulin Receptor Substrate Proteins
- Intracellular Signaling Peptides and Proteins
- Male
- Melanocyte-Stimulating Hormones/adverse effects
- Melanocyte-Stimulating Hormones/pharmacology
- Oligodeoxyribonucleotides, Antisense
- Phosphoproteins/metabolism
- Phosphorylation
- Rats
- Rats, Sprague-Dawley
- Receptor, Melanocortin, Type 3
- Receptor, Melanocortin, Type 4
- Receptors, Corticotropin/agonists
- Receptors, Corticotropin/antagonists & inhibitors
- Receptors, Corticotropin/metabolism
- Receptors, Peptide/agonists
- Receptors, Peptide/antagonists & inhibitors
- Receptors, Peptide/genetics
- Receptors, Peptide/metabolism
- Signal Transduction
- alpha-MSH/adverse effects
- alpha-MSH/pharmacology
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research-article |
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125 |
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Agoff SN, Brentnall TA, Crispin DA, Taylor SL, Raaka S, Haggitt RC, Reed MW, Afonina IA, Rabinovitch PS, Stevens AC, Feng Z, Bronner MP. The role of cyclooxygenase 2 in ulcerative colitis-associated neoplasia. THE AMERICAN JOURNAL OF PATHOLOGY 2000; 157:737-45. [PMID: 10980113 PMCID: PMC1885705 DOI: 10.1016/s0002-9440(10)64587-7] [Citation(s) in RCA: 125] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 05/23/2000] [Indexed: 02/07/2023]
Abstract
Cyclooxygenase 2 (COX-2) overexpression has been described in sporadic colonic neoplasia, but its role in ulcerative colitis (UC) neoplastic progression remains unexplored. Although the specific role of cyclooxygenase in colonic neoplasia is uncertain, its inhibition by nonsteroidal anti-inflammatory drugs decreases the risk of sporadic colonic adenocarcinoma and causes regression of adenomas in familial adenomatous polyposis. To investigate the role of COX-2 in UC-associated neoplasia, we assessed COX-2 protein and mRNA expression throughout the spectrum of UC-associated neoplastic lesions in four total colectomy specimens, using immunocytochemistry and a novel TaqMan reverse transcriptase-polymerase chain reaction assay. The findings were correlated with DNA ploidy and inflammatory activity. We found COX-2 overexpression throughout the neoplastic spectrum in UC (P: < 0.0001, R:(2)=0.53), even in diploid samples that were negative for dysplasia. Overall, neoplastic change explained 53% of the variation in COX-2 expression, whereas inflammatory activity explained only 11%. COX-2 was overexpressed in all aneuploid samples and in 38% of diploid samples (P: = 0.0074). cDNA representational difference analysis was also performed and revealed that COX-2 mRNA was an up-regulated cDNA representational difference analysis difference product. COX-2 overexpression occurs early in UC-associated neoplasia, and the increase cannot be explained by inflammatory activity alone. The data suggest that COX-2-specific inhibitors may have a chemopreventative role in UC but the possibility that they could exacerbate UC inflammatory activity needs to be tested.
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Feng Z, Jiang B, Chandra J, Ghannoum M, Nelson S, Weinberg A. Human beta-defensins: differential activity against candidal species and regulation by Candida albicans. J Dent Res 2005; 84:445-50. [PMID: 15840781 DOI: 10.1177/154405910508400509] [Citation(s) in RCA: 119] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Oral epithelial cell-derived human beta-defensins-1, -2, and -3 participate in innate immune responses against Candida. We hypothesized that these peptides utilize several mechanisms for protection. Recombinant hBD-1 and -2 were produced with the use of an insect cell/baculovirus expression system, while rhBD-3 was expressed as a fusion protein in E. coli. RhBD-2 and -3 were more effective at killing the candidal species at low micromolar concentrations than was rhBD-1, except for C. glabrata. While this species was relatively resistant to rhBD fungicidal activity, its adherence to oral epithelial cells was strain-specifically inhibited by the rhBDs. C. albicans hyphae were important in regulating hBD2 and -3 mRNA expression in primary human oral epithelial cells. Confocal microscopy of rhBD-2-challenged C. albicans suggests disruption of the fungal membrane. Results support the hypothesis that hBDs control fungal colonization through hyphal induction, direct fungicidal activity, and inhibition of candidal adherence.
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Research Support, U.S. Gov't, P.H.S. |
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Incomplete treatment of patients with infectious tuberculosis (TB) may not only lead to relapse but also to the development of antibiotic resistant TB-one of the most serious health problems facing society today. In this article, we formulate one-strain and two-strain TB models to determine possible mechanisms that may allow for the survival and spread of naturally resistant strains of TB as well as antibiotic-generated resistant strains of TB. Analysis of our models shows that non-antibiotic co-existence is possible but rare for naturally resistant strains while co-existence is almost the rule for strains that result from the lack of compliance with antibiotic treatment by TB infected individuals.
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Abstract
We investigate by simulation the properties of four different estimation procedures under a linear model for correlated data with Gaussian error: maximum likelihood based on the normal mixed linear model; generalized estimating equations; a four-stage method, and a bootstrap method that resamples clusters rather than individuals. We pay special attention to the group randomized trials where the number of independent clusters is small, cluster sizes are big, and the correlation within the cluster is weak. We show that for balanced and near balanced data when the number of independent clusters is small (< or = 10), the bootstrap is superior if analysts do not want to impose strong distribution and covariance structure assumptions. Otherwise, ML and four-stage methods are slightly better. All four methods perform well when the number of independent clusters reaches 50.
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Comparative Study |
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Cáceres NE, Harris NB, Wellehan JF, Feng Z, Kapur V, Barletta RG. Overexpression of the D-alanine racemase gene confers resistance to D-cycloserine in Mycobacterium smegmatis. J Bacteriol 1997; 179:5046-55. [PMID: 9260945 PMCID: PMC179361 DOI: 10.1128/jb.179.16.5046-5055.1997] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
D-Cycloserine is an effective second-line drug against Mycobacterium avium and Mycobacterium tuberculosis. To analyze the genetic determinants of D-cycloserine resistance in mycobacteria, a library of a resistant Mycobacterium smegmatis mutant was constructed. A resistant clone harboring a recombinant plasmid with a 3.1-kb insert that contained the glutamate decarboxylase (gadA) and D-alanine racemase (alrA) genes was identified. Subcloning experiments demonstrated that alrA was necessary and sufficient to confer a D-cycloserine resistance phenotype. The D-alanine racemase activities of wild-type and recombinant M. smegmatis strains were inhibited by D-cycloserine in a concentration-dependent manner. The D-cycloserine resistance phenotype in the recombinant clone was due to the overexpression of the wild-type alrA gene in a multicopy vector. Analysis of a spontaneous resistant mutant also demonstrated overproduction of wild-type AlrA enzyme. Nucleotide sequence analysis of the overproducing mutant revealed a single transversion (G-->T) at the alrA promoter, which resulted in elevated beta-galactosidase reporter gene expression. Furthermore, transformants of Mycobacterium intracellulare and Mycobacterium bovis BCG carrying the M. smegmatis wild-type alrA gene in a multicopy vector were resistant to D-cycloserine, suggesting that AlrA overproduction is a potential mechanism of D-cycloserine resistance in clinical isolates of M. tuberculosis and other pathogenic mycobacteria. In conclusion, these results show that one of the mechanisms of D-cycloserine resistance in M. smegmatis involves the overexpression of the alrA gene due to a promoter-up mutation.
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