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排序方式: 共有209条查询结果,搜索用时 15 毫秒
201.
Claudio A. Caamaño Julio M. Azcurra Otto Z. Sellinger Robert Zand 《Journal of neurochemistry》1989,53(6):1883-1888
The charge isoforms (C1-C5) of bovine myelin basic protein (MBP) were used as substrates for the rat brain enzyme protein carboxylmethyltransferase (PM II). The objective of these experiments was to ascertain whether the kinetic behavior of the MBP isoforms reflected differences in the structures of this molecular family. Initial velocity plots as a function of the MBP-isoform concentration showed significant differences (p less than 0.05) among the assayed isoforms except for isoforms C2 and C4. Under the conditions of our experiment all the curves exhibited a consistent sigmoidicity. The kinetic data were best fitted by a model, previously described for the enzyme D-beta-hydroxybutyrate dehydrogenase, in which two independent sites must be randomly occupied before any catalytic activity can occur. This mechanism is substantially different from that proposed by other investigators for similar PM II enzymes and other substrates. The differences in the rates of isoform carboxylmethylation are largely accounted for by the different apparent dissociation constants Ks and is explained on the basis of inherent structural differences among the charge isoforms. 相似文献
202.
Parker M. Pennington PhD Kira L. Marshall MS Jonnie M. Capiro MS Lauren Howard DVM Barbara S. Durrant PhD 《Zoo biology》2020,39(2):141-144
All extant species in the Rhinocerotidae family are experiencing escalating threats in the wild, making self-sustaining captive populations essential genetic reservoirs for species survival. Assisted reproductive technologies (ARTs) will become increasingly important for achieving and maintaining ex situ population sustainability and genetic diversity. Previous reports have shown that a large proportion of captive southern white rhinoceros (SWR) females are irregularly cyclic or acyclic, and that cycling females display two different estrous cycle lengths of approximately 30 or 70 days. It has been suggested that the longer estrous cycle length is infertile or subfertile, as no term pregnancies have been observed following long cycles. Here we report the achievement of two pregnancies following long luteal phases, using ovulation induction and artificial insemination with either fresh or frozen-thawed semen. One female SWR conceived on the first insemination attempt and gave birth to a live offspring. A second female conceived twice in consecutive long cycles although the first embryo was resorbed by 33 days post-insemination. A pregnancy from this female's second insemination is ongoing with expected parturition in November 2019. Whether prolonged estrous cycles in SWR are subfertile or infertile in natural breeding situations remains unclear. However, our findings demonstrate that the application of ARTs following prolonged cycles can result the successful establishment of pregnancies in SWR. Therefore, with ARTs, female SWR otherwise considered nonreproductive due to long estrous cycles may still have the potential for representation and contribution to the ex situ population. 相似文献
203.
Long-term observation of cultured cells by interference-reflection microscopy: near-infrared illumination and Y-contrast image processing 总被引:2,自引:0,他引:2
Interference-reflection microscopy (IRM) is the only method presently available with which to visualize cell-substratum adhesions in living tissue culture cells continuously for long periods of time without the use of fluorescent markers (Curtis: J. Cell Biol. 20:199-215, 1964; Izzard and Lochner: J. Cell Sci. 21:129-159, 1976). This method utilizes approximately 1% of the incident illumination to produce the IRM image (Verschueren: J. Cell Sci. 75:279-301, 1985) and so far has required the use of high-intensity light sources in the visible spectral range (400-800 nm). Unfortunately, visible light of this intensity and spectral range induces marked changes in the behavior and morphology of motile fibroblasts, including cessation of locomotion. In contrast, the present paper reports that continuous observations of live cells in IRM for periods of up to 8 hours are possible if the illuminating light is in the red to near-infrared range (650-950 nm) and without any observable change in normal cell morphology or behavior. In addition, we describe how the technique of Y-contrast image processing can be applied to IRM images to create a three-dimensional image of the ventral cell surface topography. 相似文献
204.
Yan Chao Cui Yu Sheng Qiu Qiong Wu Gang Bu Amira Peli Seoh Wei Teh Kok Pian Ang Narcisse MS Joseph Avin Ee-Hwan Koh Aisha Farhana Badr Alzahrani Mohammed Safwan Ali Khan Antony V Samrot Pooi Ling Mok Suresh Kumar Subbiah 《Experimental biology and medicine (Maywood, N.J.)》2021,246(10):1177
Osteoblasts play an important role in bone regeneration and repair. The hypoxia condition in bone occurs when bone undergoes fracture, and this will trigger a series of biochemical and mechanical changes to enable bone repair. Hence, it is interesting to observe the metabolites and metabolism changes when osteoblasts are exposed to hypoxic condition. This study has looked into the response of human osteoblast hFOB 1.19 under normoxic and hypoxic conditions by observing the cell growth and utilization of metabolites via Phenotype MicroArrays™ under these two different oxygen concentrations. The cell growth of hFOB 1.19 under hypoxic condition showed better growth compared to hFOB 1.19 under normal condition. In this study, osteoblast used glycolysis as the main pathway to produce energy as hFOB 1.19 in both hypoxic and normoxic conditions showed cell growth in well containing dextrin, glycogen, maltotriose, D-maltose, D-glucose-6-phospate, D-glucose, D-mannose, D-Turanose, D-fructose-6-phosphate, D-galactose, uridine, adenosine, inosine and α-keto-glutaric acid. In hypoxia, the cells have utilized additional metabolites such as α-D-glucose-1-phosphate and D-fructose, indicating possible activation of glycogen synthesis and glycogenolysis to metabolize α-D-glucose-1-phosphate. Meanwhile, during normoxia, D-L-α-glycerol phosphate was used, and this implies that the osteoblast may use glycerol-3-phosphate shuttle and oxidative phosphorylation to metabolize glycerol-3-phosphate. 相似文献
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207.
Jannat Ali Pour Naghmeh Meshkani Reza Toolabi Karamollah Mohassel Azadi Samaneh Zand Shahabedin Emamgholipour Solaleh 《Molecular biology reports》2020,47(5):3459-3468
Molecular Biology Reports - It is well-established that an impaired adipose tissue function and morphology caused by a dysregulated gene expression contribute substantially to obesity. Nowadays,... 相似文献
208.
209.
MS Nandhu Jes Paul Korah P Kuruvilla Anitha Malat Chinthu Romeo CS Paulose 《Journal of biomedical science》2011,18(1):5
Parkinson's disease is characterized by progressive cell death in the substantia nigra pars compacta, which leads to dopamine
depletion in the striatum and indirectly to cortical dysfunction. Increased glutamatergic transmission in the basal ganglia
is implicated in the pathophysiology of Parkinson's disease and glutamate receptor mediated excitotoxicity has been suggested
to be one of the possible causes of the neuronal degeneration. In the present study, the effects of serotonin, gamma-aminobutyric
acid and bone marrow cells infused intranigrally to substantia nigra individually and in combination on unilateral 6-hydroxydopamine
induced Parkinson's rat model was analyzed. Scatchard analysis of total glutamate and NMDA receptor binding parameters showed
a significant increase in Bmax (P < 0.001) in the cerebral cortex of 6-hydroxydopamine infused rat compared to control. Real Time PCR amplification of NMDA2B,
mGluR5, bax, and ubiquitin carboxy-terminal hydrolase were up regulated in cerebral cortex of 6-hydroxydopamine infused rats
compared to control. Gene expression studies of GLAST, ά-Synuclien and Cyclic AMP response element-binding protein showed
a significant (P < 0.001) down regulation in 6-OHDA infused rats compared to control. Behavioural studies were carried out
to confirm the biochemical and molecular studies. Serotonin and GABA along with bone marrow cells in combination showed reversal
of glutamate receptors and behaviour abnormality shown in the Parkinson's rat model. The therapeutic significance in Parkinson's
disease is of prominence. 相似文献