Use of gene expression profiling to identify candidate genes for pretherapeutic patient classification in acute appendicitis.

BACKGROUND: Phlegmonous and gangrenous appendicitis represent independent pathophysiological entities with different clinical courses ranging from spontaneous resolution to septic disease. However, reliable predictive methods for these clinical phenotypes have not yet been established. In an attempt to provide pathophysiological insights into the matter, a genomewide gene expression analysis was undertaken in patients with acute appendicitis. METHODS: Peripheral blood mononuclear cells were isolated and, after histological confirmation of PA or GA, analysed for genomewide gene expression profiling using RNA microarray technology and subsequent pathway analysis. RESULTS: Samples from 29 patients aged 7-17 years were included. Genomewide gene expression analysis was performed on 13 samples of phlegmonous and 16 of gangrenous appendicitis. From a total of 56 666 genes, 3594 were significantly differently expressed. Distinct interaction between T and B cells in the phlegmonous appendicitis group was suggested by overexpression of T cell receptor α and ß subunits, CD2, CD3, MHC II, CD40L, and the B cell markers CD72 and CD79, indicating an antiviral mechanism. In the gangrenous appendicitis group, expression of genes delineating antibacterial mechanisms was found. CONCLUSION: These results provide evidence for different and independent gene expression in phlegmonous and gangrenous appendicitis in general, but also suggest distinct immunological patterns for the respective entities. In particular, the findings are compatible with previous evidence of spontaneous resolution in phlegmonous and progressive disease in gangrenous appendicitis.

Water use by Eucalyptus tereticornis stands of differing density in southern India.

We studied water use by Eucalyptus tereticornis Sm. in two plantations, differing in tree density (1800 stems ha(-1) at Site I and 1090 stems ha(-1) at Site II), in different years. At both sites, stomatal conductance, predawn and midday water potentials and microclimate were measured and used to estimate hourly transpiration by the Penman-Monteith equation. Growth in girth was also measured. Stomatal conductance was closely correlated with atmospheric vapor pressure deficit (D); however, stomata did not close completely even at high D ( approximately 5.0 kPa). Midday leaf water potentials did not fall below -2.0 MPa during any part of the year at either site. Predawn leaf water potentials were greater than -0.25 MPa during the postmonsoon period, but declined to -0.7 MPa at Site I during the premonsoon period. Transpiration estimates ranged from 0.6 to 1.2 mm h(-1) at Site I and from 0.2 to 0.6 mm h(-1) at Site II. The extrapolated transpiration values for the rain-free days of the year were 1563 mm and 853 mm for Sites I and II, respectively. Growth in girth was negligible during the premonsoon period. Photosynthesis was not affected by the minor water stress that developed during the premonsoon period.

Transport of hexoses by the phloem of Ricinus communis L. seedlings.

The sieve-tube sap of Ricinus communis L. seedlings has been analysed to determine whether or not hexoses can be taken up by the phloem. Under natural conditions, i.e. with the endosperm attached to the cotyledons, glucose and fructose occurred only in trace amounts in the sieve-tube sap. Incubation of the cotyledons with hexoses in the concentration range 25-200 mM caused a rapid and substantial uptake of hexoses into the phleom, where they appeared eventually in the sieve-tube sap at the same concentration as in the incubation medium. Phloem loading of glucose, 3-O-methyl-glucose and sorbitol occurred easily, whereas fructose was less well loaded. glucose and to a larger extent fructose were also transformed to sucrose, which was loaded into the phloem. The loading of hexoses into the sieve tubes as observed in the experimental exudation system also occurred in the intact seedling, but transloction in the latter soon came to a standstill, probably because of lack of consumption by the sink tissues. These results indicate that the virtual absence of hexoses in the sievetube sap under in-vivo conditions is not because of the inability of the phloem-loading system to transport the monosaccharides but because of the absence of sufficiently high concentrations in the apoplast.

Sucrose transport into the phloem of Ricinus communis L. seedlings as measured by the analysis of sieve-tube sap.

Careful cutting of the hypocotyl of Ricinus communis L. seedlings led to the exudation of pure sieve-tube sap for 2-3 h. This offered the possibility of testing the phloem-loading system qualitatively and quantitatively by incubating the cotyledons with different solutes of various concentrations to determine whether or not these solutes were loaded into the sieve tubes. The concentration which was achieved by loading and the time course could also be documented. This study concentrated on the loading of sucrose because it is the major naturally translocated sieve-tube compound. The sucrose concentration of sieve-tube sap was approx. 300 mM when the cotyledons were buried in the endosperm. When the cotyledons were excised from the endosperm and incubated in buffer, the sucrose concentration decreased gradually to 80-100 mM. This sucrose level was maintained for several hours by starch breakdown. Incubation of the excised cotyledons in sucrose caused the sucrose concentration in the sieve tubes to rise from 80 to 400 mM, depending on the sucrose concentration in the medium. Thus the sucrose concentration in the sieve tubes could be manipulated over a wide range. The transfer of labelled sucrose to the sieve-tube sap took 10 min; full isotope equilibration was finally reached after 2 h. An increase of K(+) in the medium or in the sieve tubes did not change the sucrose concentration in the sievetube sap. Similarly the experimentally induced change of sucrose concentration in the sieve tubes did not affect the K(+) concentration in the exudate. High concentrations of K(+), however, strongly reduced the flow rate of exudation. Similar results were obtained with Na(+) (data not shown). The minimum translocation speed in the sieve tubes in vivo was calculated from the growth increment of the seedling to be 1.03 m·h(-1), a value, which on average was also obtained for the exudation system with the endosperm attached. This comparison of the in-vivo rate of phloem transport and the exudation rate from cut hypocotyls indicates that sink control of phloem transport in the seedlings of that particular age was small, if there was any at all, and that the results from the experimental exudation system were probably not falsified by removal of the sink tissues.