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Mei M, Likova L. Opposite Training Effect in the Ventral Pathway for Tactile Face Perception in Congenital and Late-Onset Blindness. J Vis 2012. [DOI: 10.1167/12.9.706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Profit J, Gould JB, Zupancic JAF, Stark AR, Wall KM, Kowalkowski MA, Mei M, Pietz K, Thomas EJ, Petersen LA. Formal selection of measures for a composite index of NICU quality of care: Baby-MONITOR. J Perinatol 2011; 31:702-10. [PMID: 21350429 PMCID: PMC3205234 DOI: 10.1038/jp.2011.12] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2010] [Revised: 01/07/2011] [Accepted: 01/18/2011] [Indexed: 11/09/2022]
Abstract
OBJECTIVE To systematically rate measures of care quality for very low birth weight infants for inclusion into Baby-MONITOR, a composite indicator of quality. STUDY DESIGN Modified Delphi expert panelist process including electronic surveys and telephone conferences. Panelists considered 28 standard neonatal intensive care unit (NICU) quality measures and rated each on a 9-point scale taking into account pre-defined measure characteristics. In addition, panelists grouped measures into six domains of quality. We selected measures by testing for rater agreement using an accepted method. RESULT Of 28 measures considered, 13 had median ratings in the high range (7 to 9). Of these, 9 met the criteria for inclusion in the composite: antenatal steroids (median (interquartile range)) 9(0), timely retinopathy of prematurity exam 9(0), late onset sepsis 9(1), hypothermia on admission 8(1), pneumothorax 8(2), growth velocity 8(2), oxygen at 36 weeks postmenstrual age 7(2), any human milk feeding at discharge 7(2) and in-hospital mortality 7(2). Among the measures selected for the composite, the domains of quality most frequently represented included effectiveness (40%) and safety (30%). CONCLUSION A panel of experts selected 9 of 28 routinely reported quality measures for inclusion in a composite indicator. Panelists also set an agenda for future research to close knowledge gaps for quality measures not selected for the Baby-MONITOR.
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Likova L, Mei M, Nicholas S. Does primary visual cortex operate in the universal language of modality-independent space? Insights from fMRI in the congenitally and late blind. J Vis 2011. [DOI: 10.1167/11.11.995] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Minniti G, Armosini V, Salvati M, Lanzetta G, Caporello P, Mei M, Osti MF, Maurizi RE. Fractionated stereotactic reirradiation and concurrent temozolomide in patients with recurrent glioblastoma. J Neurooncol 2010; 103:683-91. [DOI: 10.1007/s11060-010-0446-8] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2010] [Accepted: 10/21/2010] [Indexed: 12/20/2022]
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Mei M, Betts L, Wilkinson F, Wilson H. Adaptation to Up/Down Head Rotation in Face Selective Cortical Areas. J Vis 2010. [DOI: 10.1167/10.7.614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Mei M, Wilson H. Effects of normal aging on face view adaptation. J Vis 2010. [DOI: 10.1167/9.8.1059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Mei M, Leat S. Objective assessment of improved visibility with digital image enhancement for the visually impaired. J Vis 2010. [DOI: 10.1167/7.9.1045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Biscardi S, Russo D, Casciani V, Cesarini D, Mei M, Boitani L. Foraging requirements of the endangered long-fingered bat: the influence of micro-habitat structure, water quality and prey type. J Zool (1987) 2007. [DOI: 10.1111/j.1469-7998.2007.00337.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Xu L, Mei M, Ma X, Ponder KP. High expression reduces an antibody response after neonatal gene therapy with B domain-deleted human factor VIII in mice. J Thromb Haemost 2007; 5:1805-12. [PMID: 17596134 DOI: 10.1111/j.1538-7836.2007.02629.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
BACKGROUND Gene therapy could prevent bleeding in patients with hemophilia A, but might induce antibodies that block factor VIII (FVIII) function. OBJECTIVES To test the efficacy of gene therapy in the newborn period for preventing a response to human FVIII (hFVIII) because of immaturity of the immune system. METHODS Varying doses of a retroviral vector (RV) expressing a B domain-deleted hFVIII cDNA were injected i.v. into newborn hemophilia A C57BL/6 or normal C3H mice. Mice were evaluated for hFVIII expression, hemostasis, and development of anti-hFVIII antibodies with inhibitory activity. RESULTS AND CONCLUSIONS Injection of a high RV dose [10(10) transducing units (TU) kg(-1)] into newborn hemophilia A or C3H mice resulted in 61% and 13% of normal hFVIII antigen in plasma, respectively; most mice did not produce anti-hFVIII antibodies, and hemophilia A mice did not bleed. Furthermore, most mice with >20 ng mL(-1) of hFVIII in plasma (10% normal, 1 x 10(-10) m) were tolerant to hFVIII, as an antibody response was markedly reduced after challenge with hFVIII with or without adjuvant. However, most RV-treated animals with lower antigen levels developed antibodies before or after challenge. Thus, initiation of a gene therapy trial with low RV doses might increase inhibitor formation. Furthermore, frequent hFVIII infusions in newborns with hemophilia A might reduce inhibitor formation. Finally, difficulties in achieving tolerance after gene therapy for hemophilia A as compared to hemophilia B may relate to lower expression of FVIII than FIX, as high antigen levels are most effective at inducing tolerance.
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Mei M, Syed NH, Gao W, Thaxton PM, Smith CW, Stelly DM, Chen ZJ. Genetic mapping and QTL analysis of fiber-related traits in cotton ( Gossypium). TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2004; 108:280-91. [PMID: 14513220 DOI: 10.1007/s00122-003-1433-7] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2003] [Accepted: 08/12/2003] [Indexed: 05/10/2023]
Abstract
Cotton, the leading natural fiber crop, is largely produced by two primary cultivated allotetraploid species known as Upland or American cotton ( Gossypium hirsutum L.) and Pima or Egyptian cotton ( G. barbadense L.). The allotetraploid species diverged from each other and from their diploid progenitors (A or D genome) through selection and domestication after polyploidization. To analyze cotton AD genomes and dissect agronomic traits, we have developed a genetic map in an F2 population derived from interspecific hybrids between G. hirsutum L. cv. Acala-44 and G. barbadense L. cv. Pima S-7. A total of 392 genetic loci, including 333 amplified fragment length polymorphisms (AFLPs), 47 simple sequence repeats (SSRs), and 12 restriction fragment length polymorphisms (RFLPs), were mapped in 42 linkage groups, which span 3,287 cM and cover approximately 70% of the genome. Using chromosomal aneuploid interspecific hybrids and a set of 29 RFLP and SSR framework markers, we assigned 19 linkage groups involving 223 loci to 12 chromosomes. Comparing four pairs of homoeologous chromosomes, we found that with one exception linkage distances in the A-subgenome chromosomes were larger than those in their D-subgenome homoeologues, reflecting higher recombination frequencies and/or larger chromosomes in the A subgenome. Segregation distortion was observed in 30 out of 392 loci mapped in cotton. Moreover, approximately 29% of the RFLPs behaved as dominant loci, which may result from rapid genomic changes. The cotton genetic map was used for quantitative trait loci (QTL) analysis using composite interval mapping and permutation tests. We detected seven QTLs for six fiber-related traits; five of these were distributed among A-subgenome chromosomes, the genome donor of fiber traits. The detection of QTLs in both the A subgenome in this study and the D subgenome in a previous study suggests that fiber-related traits are controlled by the genes in homoeologous genomes, which are subjected to selection and domestication. Some chromosomes contain clusters of QTLs and presumably contribute to the large amount of phenotypic variation that is present for fiber-related traits.
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Povazay B, Bizheva K, Hermann B, Unterhuber A, Sattmann H, Fercher A, Drexler W, Schubert C, Ahnelt P, Mei M, Holzwarth R, Wadsworth W, Knight J, Russell PSJ. Enhanced visualization of choroidal vessels using ultrahigh resolution ophthalmic OCT at 1050 nm. OPTICS EXPRESS 2003; 11:1980-6. [PMID: 19466083 DOI: 10.1364/oe.11.001980] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
In this article the ability of ultrahigh resolution ophthalmic optical coherence tomography (OCT) to image small choroidal blood vessels below the highly reflective and absorbing retinal pigment epithelium is demonstrated for the first time. A new light source (lambdac= 1050 nm, Deltalambda = 165 nm, Pout= 10 mW), based on a photonic crystal fiber pumped by a compact, self-starting Ti:Al2O3 laser has therefore been developed. Ex-vivo ultrahigh resolution OCT images of freshly excised pig retinas acquired with this light source demonstrate enhanced penetration into the choroid and better visualization of choroidal vessels as compared to tomograms acquired with a state-of-the art Ti:Al2O3 laser (Femtolasers Compact Pro, lc= 780 nm, Deltalambda= 160 nm, Pout= 400 mW), normally used in clinical studies for in vivo ultrahigh resolution ophthalmic OCT imaging. These results were also compared with retinal tomograms acquired with a novel, spectrally broadened fiber laser (MenloSystems, lambdac= 1350 nm, Deltalambda= 470 nm, Pout = 4 mW) permitting even greater penetration in the choroid. Due to high water absorption at longer wavelengths retinal OCT imaging at ~1300 nm may find applications in animal ophthalmic studies. Detection and follow-up of choroidal neovascularization improves early diagnosis of many retinal pathologies, e.g. age-related macular degeneration or diabetic retinopathy and can aid development of novel therapy approaches.
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Bizheva K, Povazay B, Hermann B, Sattmann H, Drexler W, Mei M, Holzwarth R, Hoelzenbein T, Wacheck V, Pehamberger H. Compact, broad-bandwidth fiber laser for sub-2-microm axial resolution optical coherence tomography in the 1300-nm wavelength region. OPTICS LETTERS 2003; 28:707-9. [PMID: 12747714 DOI: 10.1364/ol.28.000707] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
A novel, compact, user friendly fiber laser with a broad emission bandwidth (MenloSystems, lambdac = 1375 nm, deltalambda = 470 nm, Pout = 4 mW) was used to achieve unprecedented sub-2-microm axial resolution optical coherence tomography (OCT) in nontransparent biological tissue in the 1300-nm wavelength region. Fresh human skin and arterial biopsies were imaged ex vivo with approximately 1.4-microm axial and approximately 3-microm lateral resolution and 95-dB sensitivity, demonstrating the great potential for clinical OCT applications of this stable, low-cost, and turn-on-key fiber laser.
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Mei M, Weitz M. Controlled decoherence in multiple beam Ramsey interference. PHYSICAL REVIEW LETTERS 2001; 86:559-563. [PMID: 11177881 DOI: 10.1103/physrevlett.86.559] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2000] [Indexed: 05/23/2023]
Abstract
We have scattered photons from an interfering path of a multiple beam Ramsey interference experiment realized with a cesium atomic beam. It is demonstrated that in multiple beam interference the decoherence from photon scattering cannot only lead to a decrease but, under certain conditions, also to an increase of the Michelson fringe contrast. In all cases, the atomic quantum state loses information with photon scattering, as "which-path" information is carried away by the photon field. We outline an approach to quantify this which-path information from observed fringe signals, which allows for an appropriate measure of decoherence in multiple path interference.
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Mei M, Wei S, Zijian W, Wenhua W, Baohua Z, Suxia Z. [The toxicity variation of organic extracts in drinking water treatment processes]. HUAN JING KE XUE= HUANJING KEXUE 2001; 22:49-52. [PMID: 11382042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
Source water samples and outlet water samples from different treatment processes of the Beijing Ninth Water Works were concentrated in situ with XAD-2 filled columns. GC-MS analysis and toxic assessment including acute toxicity evaluation by luminescent bacterium bioassay(Q67 strains) and mutagenicity assessment by Ames test(TA98 and TA100 strains with and without S9 addition) were conducted on these samples. The results showed that prechlorination caused the direct and indirect frame shift mutagenicity as well as indirect base pair substitute mutagenicity. Addition of coagulant may increase the base pair substitute mutagenic effects greatly. Sand and coal filtration and granular activated carbon filtration could effectively remove most of the formed mutagens. The rechlorination do not obviously increase the mutagenic effects. No mutagenic effect was observed in tap water. Acute toxicity showed the same variation with that of mutagenicity during the treatment processes. Sample from flocculation treatment process was found to be the most toxic sample. Results of GC-MS analysis showed that water in this plant was not contaminated by PCB. Concentrations of toluene, naphthalene and phenol increased in flocculation treatment process and in tap water. However, the concentrations of these substances were at the level of microgram/L, therefore, were not high enough to cause mutagenicity.
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Mei M, Yu H, Zhang W, Shi J, Yang J. [Inhibition of hTR activity for suppression of lung cancer cell proliferation using antisense phosphorothioate oligonucleotides]. ZHONGHUA BING LI XUE ZA ZHI = CHINESE JOURNAL OF PATHOLOGY 2000; 29:204-7. [PMID: 11866914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
OBJECTIVE Telomerase activity was measured in 8 lung tumor cell lines and transfected antisense phosphorothiate oligodeoxynucleotides (anti-PS-ODN) of hTR as therapeutic agents into target cell LTEP-a-2 to investigate the inhibitory effect on telomerase activity and tumor cell growth. METHODS 1. Telomerase activity assay in 8 human lung tumor cell lines using telomerase PCR ELISA. 2. Synthesized anti-PS-ODNs of hTR and random PS-ODN transfected with Clonfectin into LTEP-a-2 cell lines for 72 hr. 3. Measure telomerase activity by telomerase PCR ELISA, SDH activity by MTT assay and cell growth. RESULTS Eight cell lines showed positive expression of telomerase activity. Various anti-PS-ODNs could inhibit telomerase activity, SDH activity and cell growth. The inhibition became more marked with the increase of anti-PS-ODNs concentrations. Concentrations of 5 - 40 micromol/L anti-PS-ODNs of hTR specifically reduced the telomerase activity by 25.7% - 84.0%. PS-ODNs of anti-hTR were also able to reduce SDH activity by 19.4% - 74.7% at 5 - 40 micromol/L. The dose of 5 - 40 micromol/L PS-ODNs of anti-hTR had the ability to inhibit cell growth by 14.8% - 72.5%. The results indicate that random sequence of PS-ODN(9) failed to inhibit telomerase, SDH activity and cell growth. A statistically significant difference exists between random PS-ODN and three anti-PS-ODNs (P < 0.01). CONCLUSIONS Human lung tumor cell lines express high telomerase activity. PS-ODNs of anti-hTR had the ability to inhibit telomerase and reduce LTEP-a-2 cell growth and metabolism.
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Huang G, Kang J, Zhang W, Liu L, Yu M, Mei M, Dong Y. [Toxic effects of aluminum on human embryonic cerebral neurocytes in vitro studies]. ZHONGHUA YU FANG YI XUE ZA ZHI [CHINESE JOURNAL OF PREVENTIVE MEDICINE] 2000; 34:106-8. [PMID: 11860913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
OBJECTIVE To study the toxic effect of aluminum on human embryonic cerebral neurocytes in vitro studies. METHODS Human embryonic cerebral neurocytes were divided into three groups (control, low Al and high Al groups). The growth, development and morphology of neurocytes were observed by light and electron microscopy. The protein, DNA, lipid peroxide (LPO) contents and the activity of neuron-specific enolase (NSE) and cholinesterase (CHE) of neurocytes were detected. RESULTS The number of viable cells in high Al group was significantly lower than that in the control group (P < 0.05). The number of swelling, degenerated and necrotic cells was significantly increased in high Al group. The DNA content and the activity of NSE and CHE of neurocytes were significantly decreased with the increase of Al concentrations (P < 0.05). The LPO content of neurocytes in the high Al group was significantly higher than that in the control group (P < 0.05). There was a positive correlation between the Al dose and LPO content of neurocytes (P < 0.05). The electron microscopy study showed that the membrane structure of cell was damaged in the high Al group and the arrangement of microtubules in the processes was disordered. CONCLUSIONS The growth, development and function of human embryonic cerebral neurocytes was inhibited in the high Al group. The neurotoxicity of Al may be caused by lipid peroxidation and the damage of cell membrane.
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Mei M, Xu J, Shi Q, Chen Q, Qin L. Measurement of serum circulating intercellular adhesion molecule-1 and its clinical significance in hepatocellular carcinoma: preliminary report. JOURNAL OF HEPATO-BILIARY-PANCREATIC SURGERY 1999; 6:181-5. [PMID: 10398907 DOI: 10.1007/s005340050103] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Serum circulating intercellular adhesion molecule-1 (cICAM-1) was measured in 50 patients with hepatocellular carcinoma (HCC). The mean cICAM-1 level in the 50 patients was 2220 ng/ml and 43 patients (86%) had a high level of cICAM-1 - more than 1000 ng/ml. Comparative analysis of cICAM-1 and alpha-fetoprotein (AFP) levels in the HCC patients showed that serum AFP level was negative (<20 ng/ml) in five patients or "questionable positive" (20-90 ng/ml) in ten patients, while the levels of cICAM-1 in these patients were 1810 and 1710 ng/ml, respectively. Seven patients who underwent hepatectomy had tumor recurrences during a follow-up period of 6-18 months. Their serum AFP levels were lower than 200 ng/ml (mean value, 27 ng/ml), but their mean cICAM-1 level was 1956 ng/ml at the time tumor recurrence was diagnosed. We suggest that the measurement of serum cICAM-1 is not only useful for prediction of the progression and prognosis of HCC, but that it may also be an important marker for the early diagnosis of the disease, and for monitoring postoperative recurrence, particularly in patients with low levels of serum AFP.
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Mei M, Qiu Y, Sun Y, Huang R, Yao J, Zhang Q, Hong M, Ye J. Morphological and molecular changes of maize plants after seeds been flown on recoverable satellite. ADVANCES IN SPACE RESEARCH : THE OFFICIAL JOURNAL OF THE COMMITTEE ON SPACE RESEARCH (COSPAR) 1998; 22:1691-1697. [PMID: 11542413 DOI: 10.1016/s0273-1177(99)00034-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Dry seeds of Zea mays, heterozygous for Lw1/lw1 alleles, sandwiched between nuclear track detectors aboard Chinese satellite for 15 days, were recovered and mutations in morphological characters on plants developed from these seeds, as well as their selected progenies, were investigated. The dosimetric results indicated that 85% of the seeds received at least 1 hit with Z > or = 20. About 10% of plants developed from flown seeds and 40% of observed selfed lines from the first generation plants showed some morphological changes, such as yellow stripes displayed on leaves, dwarf, anomogensis of floral organs and yellow-green seedlings, when compared with those from ground control. Using yellow stripes on leaves as the main endpoint for evaluating mutation induced in space environment, the frequency of stripe occurrence was 4.6% in the first generation plants, comparable with the results obtained from Long Duration Exposure Facility (LDEF) mission (Mei et al., 1994), but much lower than those from ground based 60 Co-gamma treatment at a dose of 100 Gy, which reached 35.5% in the selfed lines of the second generation. One hundred and ten random primers were screened in RAPD analysis to detect the variation on genomic DNA of plants with stripes on leaves. Of these primers, 10.9% were able to generate polymorphic bands between mutated plants and control, also, common band patterns in several progenies with the same mutation phenotype were observed. These results demonstrated that space radiation environment could induce inheritable mutagenic effects on plant seeds, and verified the change in genetic material in the mutants. Further study will be needed for a better understand of the nature and mechanism of this induction of mutation.
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Zou Y, Gong D, Sun L, Mei M. [Protection of hepatocyte growth factor against carbon tetrachloride injury in primary rat hepatocyte culture]. ZHONGGUO YING YONG SHENG LI XUE ZA ZHI = ZHONGGUO YINGYONG SHENGLIXUE ZAZHI = CHINESE JOURNAL OF APPLIED PHYSIOLOGY 1997; 13:228-30. [PMID: 10074269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
The protective effect of recombinant human hepatocyte growth factor (r-hHGF) against carbon tetrachloride (CCl4) injury in cultured rat hepatocytes was investigated. It was found that r-hHGF had cytoprotective effect on hepatocytes anainst CCl4 poisoning. Pretreatment with r-hHGF significantly increased the viability of cultured hepatocytes, reduced the leakage of intracellular alanine transaminase and potassium into the culture medium, as compared with the CCl4 group. The results suggest that r-hHGF may protect hepatocytes against CCl4 injury through lessening the severity of membrane lesion, preventing intracellular alanine transaminase and potassium leakage and sustaining the integrity of hepatocyte membrane.
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Zou Y, Mei M. [Effects of hepatocyte growth factor on dose- and time-response of DNA synthesis in rat hepatocytes in vitro]. ZHONGGUO YING YONG SHENG LI XUE ZA ZHI = ZHONGGUO YINGYONG SHENGLIXUE ZAZHI = CHINESE JOURNAL OF APPLIED PHYSIOLOGY 1997; 13:53-6. [PMID: 10074317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
Effects of recombinant human hepatocyte growth factor (r-hHGF) on dose- and time-response of DNA synthesis were observed by using the method of 3H-TdR incorporation into DNA in rat hepatocytes in vitro. The results showed that r-hHGF was the most potent mitogen for initiating DNA synthesis of hepatocytes, and there were dose-dependent increase in the range of 1 ng/ml (10 pmol/L)-10 ng/ml (100 pmol/L). The significant effect of r-hHGF was observed even at 1 ng/ml, and the maximal stimulatory effect was found at 10 ng/ml, which was 7-fold rise than the control. Beyond 10 ng/ml, r-hHGF inhibited hepatocyte DNA synthesis. In addition, time-response of r-hHGF on DNA synthesis was observed at 24 h, 48 h, 72 h and 96 h respectively, 3H-thymidine incorporation was higher than control group after 24 hours of incubation with r-hHGF, and reached top at 48 hours. DNA synthesis decreased after 72 and 96 hours of incubation with r-hHGF.
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Yang TC, Mei M, George KA, Craise LM. DNA damage and repair in oncogenic transformation by heavy ion radiation. ADVANCES IN SPACE RESEARCH : THE OFFICIAL JOURNAL OF THE COMMITTEE ON SPACE RESEARCH (COSPAR) 1996; 18:149-158. [PMID: 11538955 DOI: 10.1016/0273-1177(95)00801-k] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Energetic heavy ions are present in galactic cosmic rays and solar particle events. One of the most important late effects in risk assessment is carcinogenesis. We have studied the carcinogenic effects of heavy ions at the cellular and molecular levels and have obtained quantitative data on dose-response curves and on the repair of oncogenic lesions for heavy particles with various charges and energies. Studies with repair inhibitors and restriction endonucleases indicated that for oncogenic transformation DNA is the primary target. Results from heavy ion experiments showed that the cross section increased with LET and reached a maximum value of about 0.02 micrometer2 at about 500 keV/micrometer. This limited size of cross section suggests that only a fraction of cellular genomic DNA is important in radiogenic transformation. Free radical scavengers, such as DMSO, do not give any effect on induction of oncogenic transformation by 600 MeV/u iron particles, suggesting most oncogenic damage induced by high-LET heavy ions is through direct action. Repair studies with stationary phase cells showed that the amount of reparable oncogenic lesions decreased with an increase of LET and that heavy ions with LET greater than 200 keV/micrometer produced only irreparable oncogenic damage. An enhancement effect for oncogenic transformation was observed in cells irradiated by low-dose-rate argon ions (400 MeV/u; 120 keV/micrometer). Chromosomal aberrations, such as translocation and deletion, but not sister chromatid exchange, are essential for heavy-ion-induced oncogenic transformation. The basic mechanism(s) of misrepair of DNA damage, which form oncogenic lesions, is unknown.
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Yang TC, Georgy KA, Mei M, Durante M, Craise LM. Radiogenic cell transformation and carcinogenesis. ASGSB BULLETIN : PUBLICATION OF THE AMERICAN SOCIETY FOR GRAVITATIONAL AND SPACE BIOLOGY 1995; 8:106-12. [PMID: 11538546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
Radiation carcinogenesis is one of the major biological effects considered important in the risk assessment for space travel. Various biological model systems, including both cultured cells and animals, have been found useful for studying the carcinogenic effects of space radiations, which consist of energetic electrons, protons and heavy ions. The development of techniques for studying neoplastic cell transformation in culture has made it possible to examine the cellular and molecular mechanisms of radiation carcinogenesis. Cultured cell systems are thus complementary to animal models. Many investigators have determined the oncogenic effects of ionizing and nonionizing radiation in cultured mammalian cells. One of the cell systems used most often for radiation transformation studies is mouse embryonic cells (C3H10T1/2), which are easy to culture and give good quantitative dose-response curves. Relative biological effectiveness (RBE) for heavy ions with various energies and linear energy transfer (LET) have been obtained with this cell system. Similar RBE and LET relationship was observed by investigators for other cell systems. In addition to RBE measurements, fundamental questions on repair of sub- and potential oncogenic lesions, direct and indirect effect, primary target and lesion, the importance of cell-cell interaction and the role of oncogenes and tumor suppressor genes in radiogenic carcinogenesis have been studied, and interesting results have been found. Recently several human epithelial cell systems have been developed, and ionizing radiation have been shown to transform these cells. Oncogenic transformation of these cells, however, requires a long expression time and/or multiple radiation exposures. Limited experimental data indicate high-LET heavy ions can be more effective than low-LET radiation in inducing cell transformation. Cytogenetic and molecular analyses can be performed with cloned transformants to provide insights into basic genetic mechanism(s) of radiogenic transformation of human epithelial cells.
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Mei M, Deng H, Lu Y, Zhuang C, Liu Z, Qiu Q, Qiu Y, Yang TC. Mutagenic effects of heavy ion radiation in plants. ADVANCES IN SPACE RESEARCH : THE OFFICIAL JOURNAL OF THE COMMITTEE ON SPACE RESEARCH (COSPAR) 1994; 14:363-372. [PMID: 11539972 DOI: 10.1016/0273-1177(94)90489-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Genetic and developmental effects of heavy ions in maize and rice were investigated. Heavy particles with various charges and energies were accelerated at the BEVALAC. The frequency of occurrence of white-yellow stripes on leaves of plants developed from irradiated maize seeds increased linearly with dose, and high-LET heavy charged particles, e.g., neon, argon, and iron, were 2-12 times as effective as gamma rays in inducing this type of mutation. The effectiveness of high-LET heavy ion in (1) inhibiting rice seedling growth, (2) reducing plant fertility, (3) inducing chromosome aberration and micronuclei in root tip cells and pollen mother cells of the first generation plants developed from exposed seeds, and (4) inducing mutation in the second generation, were greater than that of low-LET gamma rays. All effects observed were dose-dependent; however, there appeared to be an optimal range of doses for inducing certain types of mutation, for example, for argon ions (400 MeV/u) at 90-100 Gy, several valuable mutant lines with favorable characters, such as semidwarf, early maturity and high yield ability, were obtained. Experimental results suggest that the potential application of heavy ions in crop improvement is promising. RFLP analysis of two semidwarf mutants induced by argon particles revealed that large DNA alterations might be involved in these mutants.
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Mei M, Qiu Y, He Y, Bucker H, Yang CH. Mutational effects of space flight on Zea mays seeds. ADVANCES IN SPACE RESEARCH : THE OFFICIAL JOURNAL OF THE COMMITTEE ON SPACE RESEARCH (COSPAR) 1994; 14:33-39. [PMID: 11539968 DOI: 10.1016/0273-1177(94)90447-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The growth and development of more than 500 Zea mays seeds flown on LDEF were studied. Somatic mutations, including white-yellow stripes on leaves, dwarfing, change of leaf sheath color or seedling color were observed in plants developed from these seeds. When the frequency of white-yellow formation was used as the endpoint and compared with data from ground based studies, the dose to which maize seeds might be exposed during the flight was estimated to be equivalent to 635 cGy of gamma rays. Seeds from one particular holder gave a high mutation frequency and a wide mutation spectrum. White-yellow stripes on leaves were also found in some of the inbred progenies from plants displayed somatic mutation. Electron microscopy studies showed that the damage of chloroplast development in the white-yellow stripe on leaves was similar between seeds flown on LDEF and that irradiated by accelerated heavy ions on ground.
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Yang CH, Craise LM, Durante M, Mei M. Heavy-ion induced genetic changes and evolution processes. ADVANCES IN SPACE RESEARCH : THE OFFICIAL JOURNAL OF THE COMMITTEE ON SPACE RESEARCH (COSPAR) 1994; 14:373-382. [PMID: 11538027 DOI: 10.1016/0273-1177(94)90490-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
On Moon and Mars, there will be more galactic cosmic rays and higher radiation doses than on earth. Our experimental studies showed that heavy ion radiation can effectively cause mutation and chromosome aberrations and that high-LET heavy-ion induced mutants can be irreversible. Chromosome translocations and deletions are common in cells irradiated by heavy particles, and ionizing radiations are effective in causing hyperploidy. The importance of the genetic changes in the evolution of life is an interesting question. Through evolution, there is an increase of DNA content in cells from lower forms of life to higher organisms. The DNA content, however, reached a plateau in vertebrates. By increasing DNA content, there can be an increase of information in the cell. For a given DNA content, the quality of information can be changed by rearranging the DNA. Because radiation can cause hyperploidy, an increase of DNA content in cells, and can induce DNA rearrangement, it is likely that the evolution of life on Mars will be effected by its radiation environment. A simple analysis shows that the radiation level on Mars may cause a mutation frequency comparable to that of the spontaneous mutation rate on Earth. To the extent that mutation plays a role in adaptation, radiation alone on Mars may thus provide sufficient mutation for the evolution of life.
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