Apical segment

Despite the limitations of the animal model, this preclinical experience has translated well into clinical trials. However, it is very important to note that the clinical safety profile of transendocardial delivery so far has entailed precise preinjection measurements of needle extension with the injection catheter tip deflected (to 90 degrees) and not deflected, arbitrary insistence on a maximal needle-to-wall ratio of 0.6, and a conscious decision not to inject stem cells into cardiac walls that are less than 8 mm thick or into the true apical segment. 

More than two shoots were generated from the node segments while only one from the apical segments in the above shoot culture. Therefore node segments were selected for routine shoot multiplication and cultured on MS, a half strength macro salts MS (1/2MS) or Gamborg B5 (B5) [17] medium containing 0.01 mg/1 NAA plus various concentrations of Kin or 6-benzylaminopurine (BA)(Table 2). 

Working with 5 mm apical and sub-apical segments of maize (Z. mays cv. DeKalb XL 640) roots, treatment with 3 pM epiBR increased extension growth by more than twice that in controls (39,... 

Distribution worst in apical segments of upper lobes Distribution entire lung worse in bases of lower lobes... 

Distance along the channel, x, is measured from the tight junction (x = 0) to the channel mouth x = L). The cell is at the mucosal bath osmolality, Cq + and the serosal bath is at Q + Cg. The lateral cell membrane has unit water permeabUity RTLp and transports solute into the interspace at rate N(x) (mosm/cm. s). The solute transport rate is written as a function of position because in their model, solute transport was assumed to occur only in an apical segment of the channel. In this apical segment transport, N, is constant. If is the fraction of chaimel length over which solute transport occurs, then... 

Fig. 3. Inhibition by AOA of anthocyanin production (a) and growth (b) of excised buckwheat hypocotyls (a) or excised apical segments of buckwheat hypocotyls (b).

Fig. 5A-C. Rapid changes in protein phosphorylation in roots of Merit corn. Apical segments of dark-grown roots were preloaded with for 1 h, then washed in buffer. A Dark controls were left in buffer for 15 min B for light treatment, roots were exposed to light for 7 min after 8 min dark incubation C light treatment was the same as in B. but EGTA-I-A23187 was present for 15 min. Proteins were extracted and separated by two-dimensional gel electrophoresis as described earlier [45]. Arrows indicate the phosphoproteins that are affected by light [27]...

Unfortunately, the very property of the above tissue most necessary for our auxin studies (its integrity) was itself an impediment to measurement of processes such as protein synthesis in vivo, since labelled amino acids were not taken up through the cut apex. In order to facilitate uptake into the tissue, therefore, apical segments from aged epicotyls were excised and placed with their bases in solution. 

Micropropagation of P. microphyllus seedUngs were carried out in absence of GA3 resulted in a higher percentage of germination and a lower rate of contamination [52]. The apical segment was the best explant for shoot formation grown on medium with different combinations and concentrations of BAP, zeatin, and kinetin. 

Fig. 6. Spatial distribution of net osmoticum deposition rate per mm of tissue water in the apical 10 mm of maize primary roots growing at various vemiculite water contents (see Fig. 3). The data were obtained by dividing rates per mm length (Fig. 5) by the volume of water in each segment. The inset shows root diameter as a function of distance from the apex in the different treatments. Points are means s.d. ( = 5-6). Modified from Sharp et al. (1988, 1989).

In Pins - embryos the initiation steps of apical complex formation occur normally. However, this complex cannot be maintained in mitotic neuroblasts. Hence, the importance of the maintenance of this complex for asymmetric cell division can be ascertained by assessing how Pins- neural progenitors divide. Pins- embryos exhibit all of the defects seen in insc mutants. Mitotic spindle orientation is defective. In the cells of mitotic domain 9 the 90° reorientation, which normally occurs in wild-type resulting in the orientation of the spindle along the apical—basal axis (Fig. 3A), fails to occur in the mutant (Fig. 3B). Mitotic spindle orientation of neuroblasts in the segmented CNS, deduced from DNA staining, also often fails to... 

Patchy or nodular infiltrates in the apical area of the upper lobes or the superior segment of the lower lobes. Cavitation that may show air-fluid levels as the infection progresses. 

A more recent example of this technique has been the study on human absorption characteristics of fexofenadine [109], Fexofenadine has been shown to be a substrate for P-gp in the in vitro cell lines its disposition is altered in knockout mice lacking the gene for MDRla, and co-administration of P-gp inhibitors (e.g. ketoconazole and verapamil) was shown to increase the oral bioavailability of fexofenadine [110-113], Hence, it is suggested that the pharmacokinetics of fexofenadine appears to be determined by P-gp activity. In the human model, the intestinal permeability estimated on the basis of disappearance kinetics from the jejunal segment is low, and the fraction absorbed is estimated to be 2% [114], Co-administration of verapamil/ketoconazole did not affect the intestinal permeability estimates however, an increased extent of absorption (determined by de-convolution) was demonstrated. The increased absorption of fexofenadine was not directly related to inhibition of P-gp-mediated efflux at the apical membrane of intestinal cells as intestinal Peff was unchanged. Furthermore, the effect cannot be explained by inhibition of intestinal based metabolism, as fexofenadine is not metabolised to any major extent. It was suggested that this may reflect modulation of efflux transporters in hepatocyte cells, thereby reducing hepatobiliary extraction of fexofenadine. 

Salicylic Acid Absorption. The apical 5 cm of the primary and two seminal roots from each of three plants were out into 1-cm segments to form an experimental unit (ca. 0.08 g). Incubation solution cc ijjtalned 0.5 mM KCl, 0.25 mM CaSOjj, 0.5 mM salicylic acid, 10 nCl/mL [ C]-sallcyllc acid, with 25 mM Tris and 25 mM Mes buffers mixed to obtain pH 6.5. Because the salicylic acid was dissolved in absolute ethanol, the final concentration of ethanol in the incubation solution was 1 (v/v). Root segments were transferred to test tubes containing 10 mL continuously aerated incubation solution. After the predetermined absorption time, segments were collected from the incubation solution by rapid filtration on Whatman No. 2 filter paper. 

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