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101.
R. Kanthan Dr. A. Shuaib MD FRCPC R. Griebel H. El-Alazounni H. Miyashita J. Kalra 《Neurochemical research》1996,21(5):563-566
The release of neurotransmitters principally glutamate during cerebral ischemia has been extensively studied. It is well recognized
that ischemia induced release of glutamate plays a key role in “excitotoxic” neuronal death. The role of monoaminergic neurotransmitters
is however unclear. The purpose of this study was to evaluate the extracellular norepinephrine, 3,4-dihydroxyphenylacetic
acid (DOPAC), 5-hydroxyindoleacetic acid (5-HIAA) and serotonin (5-HT) under varied degrees of ischemia in the acute focal
ischemic model of the human brain by in-vivo microdialysis. The ischemic response of these amines was correlated with the
glutamate levels. Our study concludes that these amines and metabolites can be detected in the human “stroke” model. No marked
fluctuations were noted in the levels of norepinephrine and DOPAC. However, significant changes to partial and total ischemia
were noted in the extracellular levels of 5-HIAA and 5-HT. These compounds showed a dramatic increase with the onset of ischemia
with higher detectable levels in the partial ischemic state in comparison to the total ischemic dialysate levels. The exact
role played by the differential increase in the levels of 5-HT to the other catecholamines in the pathogenesis of ischemic
neuronal damage remains unclear and warrants further study. 相似文献
102.
103.
R. Born J. Kummermehr J. Griebel K. R. Trott 《Radiation and environmental biophysics》1995,34(4):233-237
Delayed reproductive death, the appearance of colonies with a reduced cell density (impaired colonies) and the number of giant cells per colony were investigated in murine fibrosarcoma cells after irradiation with 3 to 9 Gy of x-rays. Radiation survivors were replated after reaching confluence, which occurred after 13 to 15 doublings; this procedure was repeated three times. The replating efficiency decreased in a dose-dependent manner, the survivors of 9 Gy achieving only 30% of the plating efficiency of unirradiated cells. After the third replating, i.e. after 40 to 45 doublings, the plating efficiency of the survivors approached that of the controls. The median colony size of the survivors showed a similar dose-dependent decrease, which was pronounced after the first replating but still remained significant after the third replating. The fraction of impaired colonies was increased to more than 30% in 9-Gy survivors, and though abating, the increase was still significant even after the third replating. Evidence of residual damage was also provided by the presence of giant cells. For instance, after 6 Gy irradiation and 13 to 15 doublings, the proportion of colonies with giant cells was 60%, decreasing only to 45% after 40 to 45 doublings. The number of giant cells per colony was 1.4 in colonies arising immediately after 6 Gy, decreasing to 0.9 after the third replating. These results suggest that the proliferative capacity of surviving cells is depressed even longer than their clonogenic capacity. 相似文献
104.
Higher-level snake phylogeny inferred from mitochondrial DNA sequences of 12S rRNA and 16S rRNA genes 总被引:3,自引:0,他引:3
Portions of two mitochondrial genes (12S and 16S ribosomal RNA) were
sequenced to determine the phylogenetic relationships among the major
clades of snakes. Thirty-six species, representing nearly all extant
families, were examined and compared with sequences of a tuatara and three
families of lizards. Snakes were found to constitute a monophyletic group
(confidence probability [CP] = 96%), with the scolecophidians (blind
snakes) as the most basal lineages (CP = 99%). This finding supports the
hypothesis that snakes underwent a subterranean period early in their
evolution. Caenophidians (advanced snakes), excluding Acrochordus, were
found to be monophyletic (CP = 99%). Among the caenophidians, viperids were
monophyletic (CP = 98%) and formed the sister group to the elapids plus
colubrids (CP = 94%). Within the viperids, two monophyletic groups were
identified: true vipers (CP = 98%) and pit vipers plus Azemiops (CP = 99%).
The elapids plus Atractaspis formed a monophyletic clade (CP = 99%). Within
the paraphyletic Colubridae, the largely Holarctic Colubrinae was found to
be a monophyletic assemblage (CP = 98%), and the Xenodontinae was found to
be polyphyletic (CP = 91%). Monophyly of the henophidians (primitive
snakes) was neither supported nor rejected because of the weak resolution
of relationships among those taxa, except for the clustering of Calabaria
with a uropeltid, Rhinophis (CP = 94%).
相似文献
105.
Many mainland populations of kiwi are declining because stoats (Mustela erminea) kill most of their chicks. Stoats are often trapped during conservation programmes, but the long-term effectiveness of trapping has not been measured. During continuous trapping of mammalian predators in the 9800?ha Whangarei Kiwi Sanctuary, the survival of brown kiwi (Apteryx mantelli) chicks declined over time. Following the use of sodium fluoroacetate (1080) to kill rats (Rattus spp.) and possums (Trichosurus vulpecula) and likely secondary poisoning of stoats, chick survival at Riponui increased from 5% to 56%, and the 62% chick survival at Rarewarewa was better than the 20% recorded in a trapped-only area nearby. We suggest that untrappable stoats accumulate in areas subjected to continuous predator trapping. Conservation managers should build into their long-term pest control programmes a periodic pulse of an alternative tool to kill pests that, for whatever reason, actively avoid the primary control tool. 相似文献
106.
Infectious diseases are the main cause of neonatal morbidity and mortality in humans. The World Health Organization estimated that in 1995 approximately 8 million infants died within the first year of life from infectious diseases, including 5 million during the first week of life. Some of the salient pathogens involved include herpes simplex virus, human immunodeficiency virus, hepatitis B virus, human cytomegalovirus, group B streptococcus, hemophilus and chlamydia. Infection with these pathogens usually occurs at the end of pregnancy, during birth or by breastfeeding. To reduce the risk of disease transmission, caesarian sections, prophylactic treatment with antibiotics or maternal antiviral therapy during the last trimester are used where available, together with improved neonatal care. None of these approaches, however, completely eliminates the risk of neonatal infection. Therefore, active or passive immunization of the fetus might represent an effective approach to reduce the high risk of neonatal diseases. Here, we demonstrate that a single immunization with a DNA vaccine delivered into the amniotic fluid in the oral cavity induces high serum antibody titers and a cell-mediated immune response, combined with induction of local immunity in the oral cavities of fetal lambs. 相似文献
107.
Spectral sensitivity was measured in air in the light adapted state in two harbor seals and a South American sea lion using a behavioral training technique. Increment thresholds were determined in a spectral range from 390 nm to 670 nm in a simultaneous two‐choice discrimination task. The spectral sensitivity curves show two maxima in sensitivity, one main peak with a maximum around 500 nm in the harbor seal and around 550 nm in the South American sea lion, and a second, smaller peak with a maximum in the range of 410 nm in both species. The broad shape and the position of the maximum of the spectral sensitivity curve of the harbor seals suggests that even under photopic conditions both rods and cones are contributing to the measurements since harbor seals possess only one cone type. The maximum sensitivity in the green part of the spectrum may indicate an adaptation to a specific underwater environment. 相似文献
108.
David M Markusic Niek P van Til Johan K Hiralall PJ Oude Ronald Elferink Jurgen Seppen 《BMC biotechnology》2009,9(1):85
Background
Lentiviral vectors are well suited for gene therapy because they can mediate long-term expression in both dividing and nondividing cells. However, lentiviral vectors seem less suitable for liver gene therapy because systemically administered lentiviral vectors are preferentially sequestered by liver macrophages. This results in a reduction of available virus and might also increase the immune response to the vector and vector products. 相似文献109.
Expression of N-myristoyltransferase in Human Brain Tumors 总被引:1,自引:0,他引:1
Lu Y Selvakumar P Ali K Shrivastav A Bajaj G Resch L Griebel R Fourney D Meguro K Sharma RK 《Neurochemical research》2005,30(1):9-13
N-myristoylation is a process of covalent irreversible protein modification that promotes association of proteins with membranes. Based on our previous findings of elevated N-myristoyltransferase (NMT) activity in colonic epithelial neoplasms that appears at an early stage in colonic carcinogenesis, together with elevated NMT expression in human colorectal and gallbladder carcinomas, we investigated NMT activity and protein expression of NMT1 and NMT2 in human brain tumors and documented elevated NMT activity and higher protein expressions. For the first time, we have demonstrated that NMT has the potential to be used as a marker of human brain tumors. However, further studies with larger number of patients are required to establish its role as a complementary diagnostic tool. This finding has significant implications for further understanding of biological mechanisms involved in tumorigenesis, as well as for diagnosis and therapy of human brain tumors. 相似文献
110.