Modelling the vasculature of the stem of Cyperus involucratus Rottb.: evidence for three patterns of vascular bundles.

MAIN CONCLUSION: Three independent patterns of vein formation in Cyperus involucratus Rottb. were identified based on rare spontaneous interruptions of scape vein development. A number of developmental anomalies of vascular bundles in Cyperus involucratus Rottb. were identified and they include "turnabout", "absent", "twins", "doublet", amphivasal and various stages of "arrested". These were used to develop a computer program to explain the three vasculature patterns of the scape of (a) ordered deployment of vascular bundles, (b) arrangement of tissues within vascular bundles and (c) orientation of vascular bundles with respect to stem edge. The computer model is a cell-by-cell determination of cell types and facet states.

Vascular architecture of the monocot Cyperus involucratus Rottb. (Cyperaceae).

The arrangement of vascular bundles in the stems of monocots has been described repeatedly as "scattered." But to the trained eye it is clearly ordered as verified by the use of the R index of Clark and Evans. The arrangement of bundles in leaves and sclerenchyma bundles in stems are also ordered. An equation was developed for the probability distribution frequencies (pdf) for leaf intervein distances which curiously also fits for cell size in proliferating tissues. Another equation was developed for the pdf for intervein distances in stems which can also be applied to epidermal deriviatives such as stomata and trichomes.

The concept of the eudicot shoot apical meristem as it applies to four Spiraea (Rosaceae), one Mentha (Lamiaceae) and one Euonymus (Celastraceae) cultivars based on chimeric analysis.

BACKGROUND AND AIMS: Eversporting eudicots were sought to see if they behave like gymnosperms. Behaviour of eversporting gymnosperm chimeras indicates a single apical cell is present in SAM and it would be of interest to see if eudicot chimeras have the same behaviour. METHODS: Four eversporting spireas, the pineapple mint and the Silver King euonymus were inspected for the fate of the yellow (mutant)-green (wild type) chimeras. KEY RESULTS: As with gymnosperms, unstable eudicot chimeras in the four spireas, the pineapple mint and the Silver King euonymus became stable yellow about 80 % or more of the time and 20 % or less became stable green. CONCLUSIONS: The statistically significant preponderance of chimeric fates becoming all yellow suggests that a single apical cell resides in the yellow tunica. As with gymnosperms, descendent cells of the yellow replacement corpus cell eventually take over the corpus. Here is the first chimeric set of data to support the hypothesis of a one-celled meristem in eudicots rather than the traditional view of a muticellular meristem.

Tracheid analysis and modeling of the minor veins of the coleus and smilax leaves.

Tracheid analysis was carried out on the veinlets and minor veins of the coleus (Solenostemon scutellarioides [L.] Codd) leaf. Third- to fifth-order, or minor, veins average 3.4 tracheids in tandem and they bipartition islets when these enclosed islets reach a critical size; both these features of vein length and islet size contribute to a self-similar process of vein pattern generation. An areole was calculated to be initially comprised of about ten cells making the patterning event for vein formation requiring only a few cells. An algorithmic model developed here for minor vein formation includes five production rules, and this computer model explains the 3-4 tracheids per minor vein, presence of isolated tracheids, the structure of veinlets, and the elaborate branching patterns of veinlets in coleus and other plants.

Anodic asymmetry of leaves and flowers and its relationship to phyllotaxis.

BACKGROUND AND AIMS: New approaches are needed to evaluate the various hypotheses of phyllotaxis, and an examination of anodic leaf asymmetry may be one such approach. METHODS: Data were collected on the direction of midrib curvature and leaf coil in Syngonium podophyllum, the location of floral buds in Acalypha virginica, the position of secondary leaves of Croton variegatus 'Banana' and the relative size of half-lamina in Aglaonema crispum and Calathea ornata. KEY RESULTS: All five features were exclusively anodic with respect to the direction of the genetic spiral regardless of whether the spiral was clockwise or counterclockwise. CONCLUSIONS: Any phyllotactic mechanism must include some asymmetric component which cannot be explained by the prevalent hypotheses of contact parastichies, inhibitory fields, available space, pressure waves and auxin transport. The most favourable hypothesis is the primary vasculature explanation as it includes an asymmetric feature.

Impact of American College of Surgeons verification on trauma outcomes.

OBJECTIVE: The purpose of this study was to compare the impact of trauma patient outcomes before and after Level II American College of Surgeons (ACS) verification was received in a not-for-profit community hospital. METHODS: This was a retrospective analysis of hospital discharge data for timeframes before and after Level II ACS verification was conducted. Originally, 8,674 patients were identified using the International Classification of Diseases, 9th Revision codes for trauma. These data were parsed to 7,811 patients by using International Classification of Diseases, 9th Revision codes 800 xx through 959.9 x, which signify an admitting diagnosis of trauma; 3,835 of the patients were admitted after the July 28, 1998, verification date. Blunt injuries constituted the vast majority of the patients (n = 7,488). Outcome measures studied included changes in length of stay (LOS), mortality, and total cost. Internal control was coronary artery bypass graft patients at the same hospital, and external control was trauma patients at a non-ACS hospital over the same time period. Data are presented with p values and SE and the ratio of observed/expected values on the basis of the all-payer severity-adjusted diagnosis-related group severity model. RESULTS: The two timeframes exhibited statistically different outcomes in several variables. Adjusting for severity postverification, LOS was 10% less (p < 0.000). Similarly, severity-adjusted mortality observed/expected ratios were significantly different: 0.81 before versus 0.59 after (p < 0.000). The severity-adjusted ratio of costs found that the postverification era was 5% lower (p < 0.000). The contribution margin of the trauma patient population to the hospital well exceeded any postverification costs. Both control groups exhibited no significant changes in their severity-adjusted outcomes, which could have invalidated these results. CONCLUSION: This study suggests that the efforts and resources consumed achieving ACS Level II trauma center verification appear to result in desired outcomes as evidenced by decreased LOS, reduced in-hospital mortality rates, reduced cost, and improved contribution margins.

Chimeric patterns in Juniperus chinensis 'Torulosa Variegata' (Cupressaceae) expressed during leaf and stem formation.

Juvenile leaves of the variegated Hollywood juniper, Juniperus chinensis 'Torulosa Variegata', have sectorial chimeras of variable widths and lengths. Sectors extend over several nodes often as small as 1/24 the circumference of the leaf. Other chimeras appear as light green to yellow streaks but are actually internal, dark green corpus sectors often occupying less than 1/20 of the cross sectional area of a leaf. On the basis of the sizes of these two types of sectors, there seems to be ideally about 168 founder cells comprising 63 tunica cells and 105 corpus cells; 49 of the latter are contiguous with the tunica and 66 are located deeper in the corpus. Similarly, sectoring in axillary branches of original chimeric sprays have the same types of sectoring. It is hypothesized that the outer rings of founder cells form two arcs of 12 cells around the stem apex, one for each of two leaves at a node of the decussate shoot, of a circumference of about 50 cells.