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51.
Frank S. Stay Albert Katko Christina M. Rohm Melissa A. Fix David P. Larsen 《Archives of environmental contamination and toxicology》1989,18(6):866-875
Comparisons were made among Leffler microcosms developed from four different natural communities and exposed to 0, 20, 100, 200, 500, 1,000, and 5,000 g/L atrazine, a commonly used herbicide. Atrazine reduced net primary productivity, pH, and net productivity/respiration ratios in all four microcosm communities. In three of the four communities, the lowest observed (P < 0.05) effect concentration (LOEL) was 100 g/L. In the fourth community the LOEL was 200 g/L atrazine.The sensitivity and accuracy of bioassays with four different microcosm communities were evaluated by comparing results with values reported for acute and chronic single species bioassays, other types of microcosms, and experimental ponds exposed to similar concentrations of atrazine. The ranges of sensitivity noted in these experiments were less than the range reported for single species bioassays using common test organisms and similar to those reported for other microcosms. The similarity between Leffler microcosm results and the responses reported for the experimental ponds suggests that the Leffler microcosms accurately reflected concentrations causing ecosystem level changes in the experimental ponds. 相似文献
52.
George V Dedoussis Demosthenes B Panagiotakos Nikoleta V Vidra Eirini Louizou Christina Chrysohoou Athanasios Germanos Yannis Mantas Savas Tokmakidis Christos Pitsavos Christodoulos Stefanadis 《Genetics in medicine》2005,7(6):411-416
PURPOSE: We investigated the association of a polymorphism within the promoter of TauNuF-alpha locus at the position -308 on the likelihood of having acute coronary syndromes (ACS) in Greek adults. METHODS: We studied demographic, lifestyle, and clinical information in 237 hospitalized patients (185 males) with a first event of an ACS and 237 matched by age and sex (controls) without any clinical evidence of coronary heart disease. Genotyping was performed by PCR-RFLP analysis. RESULTS: The genotype frequencies were in patients, 87% (n = 206), 12% (n = 29), and 1% (n = 2) for G/G, G/A, and A/A, and in controls, 96% (n = 227), 4% (n = 10), and 0% (n = 0) for G/G, G/A, and A/A, respectively (P = 0.04). After adjusting for age and sex, as well as various potential confounders, we observed that G/A or A/A genotypes were associated with 1.94-fold higher odds (95% CI 1.06 to 3.68) of ACS compared to G/G homozygotes. No gene to-gender or to-clinical syndrome interactions were observed. Further subgroup analysis showed that the distribution of TNF-alpha -308G>A polymorphism was associated with the presence of family history of CHD in patients, but not in controls. In particular, in G/A and A/A patients 17.2% reported family history of CHD, whereas in G/G patients, 34.5% reported family history (P = 0.036). CONCLUSIONS: Our findings may state a hypothesis of an association between the -308G>A TNF-alpha polymorphism the development of ACS and the presence of family history of CHD, in Greece. 相似文献
53.
Breast cancer micrometastases: Different interactions of carcinoma cells with normal and cancer patients' bone marrow stromata 总被引:6,自引:1,他引:6
Nicola MH Bizon R Machado JJ Sollero T Rodarte RS Nobre JS Magalhães MM Takiya CM Borojevic R 《Clinical & experimental metastasis》2003,20(5):471-479
The apparently dormant breast cancer micrometastases in haemopoietic marrow are correlated with distant metastatic carcinoma
dissemination. We studied in vitro interactions of carcinoma cells with adjacent stromata, using connective tissue cell cultures from breast and bone marrow
samples of normal donors, comparing them to the pericancerous breast tissue and bone marrows of 12 selected patients with
invasive breast carcinomas. Cancer cells were detected by immunocytochemistry and RT-PCR in all the bone marrows and in most
blood samples of the studied patients. We monitored the growth and interaction of carcinoma MCF-7 cells with the stromata.
The normal breast stroma sustained typical massive cancer growth. The pericancerous breast stroma induced the invasive mesenchymal
pattern of growth. Normal bone marrow stroma induced the same conversion and was highly adhesive, retaining the cells in the
stroma, but carcinoma patients' bone marrow stromata underwent low adhesive interactions with cancer cells, releasing them
potentially into the circulation. The semi-quantitative RT-PCR indicated an enhanced expression of the hepatocyte growth factor
and its receptor c-met in breast and bone marrow stromata of cancer patients. The input of cancer cells into the normal bone marrow may induce modifications
of the local microenvironment, favourable for growth and release of carcinoma cells into the systemic circulation, which correlate
with the poor prognosis of patients with bone marrow micrometastases.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
54.
Bartholdy C Stryhn A Hansen NJ Buus S Thomsen AR 《European journal of immunology》2003,33(7):1941-1948
DNA vaccination is an efficient way to induce CD8+ T cell memory, but it is still unclear to what extent such memory responses afford protection in vivo. To study this, we induced CD8+ memory responses directed towards defined viral epitopes, using DNA vaccines encoding immunodominant MHC class I-restricted epitopes of lymphocytic choriomeningitis virus covalently linked to beta2-microglobulin. This vaccine construct primed for a stronger recall response than did a more conventional minigene construct. Despite this, vaccinated mice were only protected against systemic infection whereas protection against the consequences of peripheral challenge was limited. Phenotypic analysis revealed that DNA vaccine-primed CD8+ T cells in uninfected mice differed from virus-primed CD8+ T cells particularly regarding expression of very-late antigen (VLA)-4, an adhesion molecule important for targeting T cells to inflammatory sites. Thus, our DNA vaccine induces a long-lived memory CD8+ T cell population that provides efficient protection against high-dose systemic infection. However, viral replication in solid non-lymphoid organs is not curtailed sufficiently fast to prevent significant virus-induced inflammation. Our results suggest that this is due to qualitative limitations of the primed CD8+ T cells. 相似文献
55.
Bensafi M Porter J Pouliot S Mainland J Johnson B Zelano C Young N Bremner E Aframian D Khan R Sobel N 《Nature neuroscience》2003,6(11):1142-1144
Neural representations created in the absence of external sensory stimuli are referred to as imagery, and such representations may be augmented by reenactment of sensorimotor processes. We measured nasal airflow in human subjects while they imagined sights, sounds and smells, and only during olfactory imagery did subjects spontaneously enact the motor component of olfaction--that is, they sniffed. Moreover, as in perception, imagery of pleasant odors involved larger sniffs than imagery of unpleasant odors, suggesting that the act of sniffing has a functional role in creating of olfactory percepts. 相似文献
56.
57.
Inhibition of nitric oxide synthase exacerbates group B streptococcus sepsis and arthritis in mice
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The role of nitric oxide in group B Streptococcus (GBS) infection was evaluated by inhibiting its production with aminoguanidine (AG). AG-treated mice displayed higher mortality rates and more frequent and severe arthritis than controls. Worsening of arthritis correlated with a higher number of GBS cells in the joints and local interleukin-1 beta production. 相似文献
58.
Weller A Leguisamo AC Towns L Ramboz S Bagiella E Hofer M Hen R Brunner D 《Developmental psychobiology》2003,42(2):194-205
The influence of the pre- and postweaning maternal environment on the offspring's phenotype was examined in 5-HT1A and 5-HT1B receptor knockout mice (KO1A and KO1B, respectively). We have previously shown that, when born to and raised by homozygous dams of the same genotype, adult KO1A are more anxious than wild-type (WT) mice, and adult KO1B are hyperactive and slightly less anxious than WT mice. We extend our studies here to the behavioral results of the offspring's own genotype, when the dam's genotype is constant, and the effects of the dam's genotype when the offspring's genotype is constant. In Experiments 1 and 2, KO1A-/- pups produced less ultrasonic vocalizations (USV) than controls in an isolation test on postnatal Day 7 when born to and reared by KO1A dams, either -/- or +/-. Heterozygous F1 pups reared by KO1A-/- dams produced more USV and were less anxious in the plus-maze at 2 to 3 months of age than F1 pups born to and reared by WT dams (Experiment 3). F1 pups reared by KO1B-/- dams produced less USV and were more anxious in the plus-maze than F1 pups reared by WT dams (Experiment 4). The results support a role for maternal effects that may comprise direct effects such as the dam's behavior and nutritional care of the pup, and possibly more complex indirect effects through the establishment of idiosyncratic dam-pup dyadic interactions. We recommend that breeding techniques that rely on same genotype (mutant-mutant or WT-WT) breeding pairs not be used to generate offspring when the focus of research is the study of gene function, but rather when familial effects need to be studied. 相似文献
59.
Husaini BA Sherkat DE Levine R Bragg R Van CA Emerson JS Mentes CM 《Journal of the National Medical Association》2002,94(2):100-106
This study examines the effectiveness of breast cancer screening education programs on mammography rates among African-American women 40 years of age and over. We conducted two types of educational programs in community settings, primarily in African-American churches. Three-month follow-up interviews were used to determine whether women who participated in programming were more likely to get a mammogram if they had not had a mammogram in the last year. Our results demonstrate that the educational programs significantly increased the likelihood of getting a mammogram when compared to a control group that received no educational programming. Further, we found that the programs were effective for motivating breast cancer screening in housing projects as well as in the churches, and that the effectiveness of the programs remained even when we controlled for socioeconomic status, depression, and age. 相似文献
60.
Dr. David Lo Christina R. Reilly Linda C. Burkly Jenefer DeKoning Terri M. Laufer Laurie H. Glimcher 《Immunologic research》1997,16(1):3-14
Ten years ago, we proposed a model for thymus function in which thymic epithelial cells are primarily responsible for imprinting
major histocompatibility complex (MHC)-restricted specificity, and bone marrow-derived macrophages or dendritic cells are
responsible for the induction of self-tolerance. Since then, transgenic and knockout models have allowed for a dissection
of thymic stromal components in vivo, leading to a new understanding of their specialized functions. We have determined that
with regard to class II-restricted CD4 T-cell development, two distinct subsets of thymic epithelium help shape the repertoire:
Cortical epithelium appears solely responsible for positive selection, whereas a fucose-bearing subset of medullary epithelium
is specialized for negative selection. This absolute separation of positive and negative selection into two distinct spatial
and temporal compartments leads to a much simpler view of the process of repertoire selection. Finally, a novel view of the
function of the thymic medulla is discussed. 相似文献