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PD Roberts 《Canadian Metallurgical Quarterly》1998,10(7):1831-1846
A general method is presented to classify temporal patterns generated by rhythmic biological networks when synaptic connections and cellular properties are known. The method is discrete in nature and relies on algebraic properties of state transitions and graph theory. Elements of the set of rhythms generated by a network are compared using a metric that quantifies the functional differences among them. The rhythms are then classified according to their location in a metric space. Examples are given, and biological implications are discussed. 相似文献
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We report the differences between using either EDTA plasma or serum in a turbidimetric assay for quantitation of C-reactive protein (CRP). A systematic discrepancy was found for these two sample materials. This was most pronounced in the low concentration range (below 20 mg1(-1)) at which lower values were found in serum than in EDTA plasma. Conversely, in the high concentration range, serum showed slightly higher values. Addition of K3-EDTA to the reaction buffer improved the kinetics for sera with low concentrations of CRP, thus increasing the sensitivity of the assay. We found an overall constant discrepancy of approximately 8% lower values in plasma than in serum (equally for low and high levels of CRP) after the addition of K3-EDTA. The most probable explanation for this effect seems to be the differing water content of serum and EDTA plasma. We discuss the role and function of EDTA in the CRP assay and suggest some hypothetical mechanisms. 相似文献
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TC Britton PD Thompson BL Day JC Rothwell LJ Findley CD Marsden 《Canadian Metallurgical Quarterly》1993,56(10):1085-1089
The response of postural wrist tremors to supramaximal median nerve stimulation was examined in patients with hereditary essential tremor (n = 10) and Parkinson's disease (n = 9), and in normal subjects mimicking wrist tremor (n = 8). The average frequency of on-going tremor was the same in all three groups. Supramaximal peripheral nerve shocks inhibited and then synchronised the rhythmic electromyographic (EMG) activity of all types of tremor. The duration of inhibition ranged from 90 to 210ms, varying inversely with the frequency of on-going tremor. There was no significant difference in mean duration of inhibition or in the timing of the first peak after stimulation on the average rectified EMG records between the three groups. The degree to which supramaximal peripheral nerve shocks could modulate the timing of rhythmic EMG bursts in the forearm flexor muscles was also quantified by deriving a resetting index. No significant difference in mean resetting index of the three groups was found. These results suggest that such studies cannot be used to differentiate between the common causes of postural wrist tremors. 相似文献
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MD Medlock JR Madsen PD Barnes DS Anthony LE Cohen RM Scott 《Canadian Metallurgical Quarterly》1997,27(3):121-128
There are many in vivo animal models for studying airway mucus secretion and hypersecretion, each with advantages and disadvantages. Use of a particular test system will depend upon the aspect of secretion to be modelled. Airway hypersecretory diseases exhibit chronic mucus hypersecretion, of which the clinical impact is predominantly in the distal airways. The majority of documented test preparations study acute secretion, invariably using tracheal preparations, but have been invaluable in elucidating the normal physiology of airway mucus secretion. Chronic models of the hypersecretory state in the distal airways have been developed, but are predominantly histologic in nature (for example quantification of increased goblet cell number). There are few investigations of mucus hypersecretion. Examination of the 'antisecretory' potential of pharmaceutical compounds has been investigated predominantly in chronic histologic models with the drug being given 'prophylactically' rather than 'therapeutically'. Refinement of chronic hypersecretory models should lead to elucidation of the connection between airway irritation, inflammation, MUC gene expression, mucous cell hyperplasia/metaplasia, airway hypersecretion and bronchial hypersecretory disease. 相似文献
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JS Plummer KA Berryman C Cai WL Cody J DiMaio AM Doherty JJ Edmunds JX He DR Holland S Levesque DR Kent LS Narasimhan JR Rubin ST Rapundalo MA Siddiqui AJ Susser Y St-Denis PD Winocour 《Canadian Metallurgical Quarterly》1998,8(23):3409-3414
The synthesis and antithrombotic activity of a series of nonpeptide bicyclic thrombin inhibitors is described. We have explored the SAR with modifications to the P1 site. The introduction of arginine mimetics at the P1 site led to potent and selective thrombin inhibitors. 相似文献