The importance of seed reserves for seedling performance: an integrated approach using morphological, physiological, and stable isotope techniques.

To investigate how seed reserves affect early seedling performance, we conducted a factorial greenhouse experiment using Lithocarpus densiflora (Tanoak). Seedlings were grown from large (5.8+/-0.7 g) and small (3.2+/-0.4 g) seeds and, following shoot emergence, seeds were either removed or left attached. Seedlings were harvested for quantification of biomass and delta13C at seven time periods following seed removal (2, 4, 8, 16, 32, 64, 128 days) and seedling photosynthesis was measured three separate time periods (2-4, 49-82, 95-128 days after seed removal). Biomass increased for all seedlings, but the increase was significantly larger for seedlings with attached seeds than with removed seeds. Seed removal just after shoot emergence significantly decreased seedling biomass, but seed removal 64 days after shoot emergence had no effect on seedling biomass. Seedling photosynthesis per unit leaf area varied by time and seed presence, but not by seed size. At the first period, seedlings with attached seeds had significantly higher photosynthetic rates than seedlings with removed seeds, at the second period there was no effect of seed removal, and at the third time period seedlings with attached seeds had significantly lower photosynthetic rates than seedlings with removed seeds. Despite temporal variation in photosynthesis per unit leaf area, seedlings with attached seeds always had significantly greater leaf area than seedlings with removed seeds, resulting in significantly higher total plant photosynthesis at all three time periods. The delta13C values of both the leaves and roots were more similar to that of the seed for seedlings with attached seeds than for seedlings with removed seeds, however, seed removal and seed size strongly affected root delta13C. This study demonstrates that seed reserves have important effects on the early growth, physiology, and delta13C of L. densiflora seedlings.

Approaches to the sellar and parasellar region: anatomic comparison of endonasal-transsphenoidal, sublabial-transsphenoidal, and transethmoidal approaches.

Various surgical approaches have been described for treating lesions which arise in the sellar region. The popular transnasal-transsphenoidal and transethmoidal-transsphenoidal approaches avoid the morbidity associated with transcranial operations while allowing enough exposure to successfully remove most lesions that arise in and around the sella. The goal of the present study was to accurately quantify the amount of exposure to the sellar and suprasellar region that the transethmoidal-transsphenoidal, endonasal-transphenoidal, and sublabial-transsphenoidal approaches provide. Each of the three approaches was performed on 14 formalin fixed heads with the aid of the operative microscope. The distances of relevant surgical landmarks, and the amount of exposure superior and anterior to the dorsum sella as well as the lateral exposure obtained through each of these approaches was carefully recorded. The mean distances were then used to calculate the volume of exposure offered by each approach. It was found that the sublabial-transsphenoidal approach afforded the greatest volume of exposure superior and anterior to the dorsum sella. The endonasal-transsphenoidal and the transethmoidal approaches were both found to offer less suprasellar volume exposure, with the transethmoidal approach offering the least. The authors believe the information obtained through this study illustrates some important anatomical relationships which can be used to advantage by the surgeon to tailor the most appropriate approach, depending upon the precise location of the lesion either within the sella or suprasellar region.

Cognitive abilities in adolescent-limited and life-course-persistent criminal offenders.

T. E. Moffitt's (1993a) hypothesis that adolescent-limited criminal offenders will have higher scores on tests of cognitive ability than life-course-persistent offenders was tested with 12 tests of cognitive ability given to a large and diverse sample of delinquent juveniles whose arrest records were collected over 20 years. This is the first investigation to empirically evaluate this proposal with longitudinal data obtained from a sample for a long enough time to distinguish life course patterns of crime. This study provided only partial support for Moffitt's hypothesis because the results varied by ethnicity. We found relatively consistent support for the hypothesis for Caucasians and Hispanics but no support for the hypothesis for African Americans. These findings are interpreted in terms of differences in developmental contexts for individual ethnic groups.

Using IRT to separate measurement bias from true group differences on homogeneous and heterogeneous scales: an illustration with the MMPI.

The authors present a didactic illustration of how item response theory (IRT) can be used to separate measurement bias from true group differences on homogeneous and heterogeneous scales. Several bias detection methods are illustrated with 12 unidimensional Minnesota Multiphasic Personality Inventory (MMPI) factor scales (Waller, 1999) and the 13 multidimensional MMPI validity and clinical scales. The article begins with a brief review of MMPI bias research and nontechnical reviews of the 2-parameter logistic model (2-PLM) and several IRT-based methods for bias detection. A goal of this article is to demonstrate that homogeneous and heterogeneous scales that are composed of biased items do not necessarily yield biased test scores. To that end, the authors perform differential item- and test-functioning analyses on the MMPI factor, validity, and clinical scales using data from 511 Blacks and 1,277 Whites from the California Youth Authority.

Short-term dynamics of an acacia ant community in Laikipia, Kenya.

In monospecific stands of Acacia drepanolobium in Laikipia, Kenya, virtually all but the smallest trees are occupied by one of four species of ants. Although trees are a limiting resource, all four ant species are maintained in this system. Three separate lines of evidence confirm a linear dominance hierarchy among these four ants: (1) experimentally staged conflicts, (2) natural transitions among 1773 tagged trees over a 6-month period, and (3) the average sizes of trees occupied by ants of different species. Short-term dynamics during a drying period reveal that many smaller trees (<1 m) occupied by dominant ants were subsequently abandoned, and that abandoned trees had grown more slowly than those that were not abandoned. Height growth increments over 6 months were generally independent of ant occupant, but increased with tree height. Among taller trees (>1 m), changes in ant occupation congruent with the dominance hierarchy (i.e., transitions from more subordinate ant species to more dominant ant species) occurred on trees that grew faster than average. In contrast, the (less frequent) changes in ant occupation "against" the direction of the dominance hierarchy occurred on trees that grew more slowly than average. Observed correlations between tree vigor and takeover direction suggest that colony growth of dominant ant species is either favored in more productive microhabitats, or that such colonies differentially seek out healthier trees for conquest. Colonies of dominant species may differentially abandon more slowly growing trees during (dry) periods of retrenchment, or suffer higher mortality on these trees. Subordinate ant species appear to move onto these abandoned trees and, to a lesser extent, colonize new recruits in the sapling class. These data reveal that within a simple linear dominance hierarchy, short-term variations exist that may reveal underlying mechanisms associated with coexistence.

Approaches to the sellar and parasellar region: anatomic comparison of the microscope versus endoscope.

OBJECTIVE: Traditionally, surgical approaches to the sellar region require the use of the operating microscope. Over the past decade endoscopic surgery has gained much popularity because of advances in optics and illumination. Endoscopic surgery of the sellar region has been performed successfully. The goal of the present study was to quantify the amount of exposure to the sellar and suprasellar region that the endoscope provides versus the microscope, with three different anterior approaches to the sellar region. METHODS: The transethmoidal, endonasal-transsphenoidal, and sublabial-transsphenoidal approaches were performed on 14 formalin-fixed cadaver heads with a 0 degrees endoscope and repeated with the operative microscope. The distances of relevant surgical landmarks and the amount of exposure superior and anterior to the dorsum sella, as well as the lateral exposure, were measured. The mean distances were then used to calculate the volume of exposure for each of the approaches. RESULTS: It was found that the endoscope provided greater view than the operating microscope in all three approaches. The difference was statistically significant using a paired Student t test and a signed-rank test (P<.001). CONCLUSION: The authors believe that endoscopic surgery of the sellar region can be performed safely and effectively, while providing the surgeon with a view that is superior to that afforded by the operating microscope.

A cadaveric study of the motor nerves to the levator scapulae muscle.

Understanding the surgical anatomic relationships of the motor nerves to the levator scapulae muscle is imperative for reducing postoperative shoulder dysfunction in patients undergoing neck dissection. To elucidate this relevant anatomy, cervical (C3, C4) and brachial (C5 via dorsal scapular nerve) plexi contributions to the levator scapulae were assessed with respect to posterior triangle landmarks in 37 human cadaveric necks. An average of approximately 2 (actual 1.92) nerves from the cervical plexus (range 1 to 4 nerves) emerged from beneath the posterior border of the sternocleidomastoid muscle in a cephalad to caudad progression to enter the posterior triangle of the neck on their way to innervating the levator scapulae. These cervical plexus contributions exhibited a fairly regular relationship to the emergence of cranial nerve XI and the punctum nervosum along the posterior border of the sternocleidomastoid muscle. After emerging from the posterior border of the sternocleidomastoid to enter the posterior triangle of the neck, cervical plexus contributions to the levator scapulae traveled for a variable distance posteriorly and inferiorly, sometimes branching or coming together. Ultimately these nerves crossed the anterior border of the levator scapulae as 1 to 3 nerves (average 1.94) in a regular superior to inferior progression. The dorsal scapular nerve from the brachial plexus exhibited highly variable anatomic relations in the inferior aspect of the posterior triangle, and was found to penetrate or give branches to the levator scapulae in only 11 of 35 neck specimens. We have found that the levator scapulae receives predictable motor supply from the cervical plexus. Our data elucidate surgical anatomy useful to head and neck surgeons.

An anatomic study of the external laryngeal framework with surgical implications.

Precise knowledge of the level of the vocal fold as projected on the external thyroid cartilage is of critical importance for the performance of thyroplasty type I and supraglottic laryngectomy. Measurements of the external laryngeal framework were made on the larynges of 18 human cadavers in order to identify landmarks that will aid the surgeon in determining endolaryngeal anatomy. On the basis of our results, the following guidelines are recommended: (1) Thyroid cartilage incision for supraglottic laryngectomy should be made on a line joining the juncture of the upper one third and lower two thirds of the midline length and the juncture of the upper one third and lower two thirds of the oblique line. This will ensure a position above the level of the anterior commissure and the true vocal cord; (2) In thyroplasty type I, the superior border of the thyroid cartilage window should be made at a line joining the midpoint of the midline length and the juncture of the upper two thirds and lower one third of the oblique line. Formation of the cartilage window according to this guideline will ensure its placement lateral to the vocalis muscle.

Prediction of diuretic mobilization of cirrhotic ascites by pretreatment fractional sodium excretion.

In a randomized prospective study the efficacy and side effects of xipamide versus the combination spironolactone/furosemide in the treatment of cirrhotic ascites were studied. Out of 27 patients four responded to a basic treatment consisting of salt and water restriction and one had to be excluded because of deterioration of kidney function. The remaining 22 patients were randomized to additional treatment with either 20 mg xipamide/day (group I) or 200 mg spironolactone/day combined with 40 mg of furosemide every other day (group II). A response to treatment during the first 4 days was seen in 7 of 11 patients of group I versus only 3 of 11 patients in group II. In the latter group 7 of 11 patients finally responded after 8 days of treatment. Responsiveness to either diuretic treatment strongly depended on pretreatment fractional Na excretion, FENa. The resistance to diuretic treatment can be predicted by a FENa less than 0.2%, and could be overcome by additional strategies known to reduce avid proximal Na reabsorption. Xipamide frequently induced hypokalemia, whereas hyperkalemia was seen following treatment with spironolactone/furosemide. Kidney function remained stable during either diuretic treatment.

Glucocorticoid target cells in human outflow pathway: autopsy and surgical specimens.

Target cells for glucocorticoids were found in trabeculectomy specimens obtained surgically from humans with glaucoma (primary and secondary) and from nonglaucomatous autopsy eyes using an autoradiographic technique. Specific nuclear localization of 3H-dexamethasone was found in cells of the trabecular meshwork, scleral fibroblasts, and in the endothelial lining of both Schlemm's canal and the outflow vessels. Glucocorticoids may alter the outflow facility by a direct effect on the metabolism of these cells. The autoradiographic method is suitable for studying competitors of glucocorticoid binding in small surgical specimens of human tissue involved in the outflow of aqueous humor.

The effect of dexamethasone on the in vitro incorporation of precursors of extracellular matrix components in the outflow pathway region of the rabbit eye.

The present study demonstrates that the cells of the outflow pathway region incorporate precursors of the extracellular matrix components during in vitro incubation. Addition of dexamethasone (10(-7) M) to the incubation mixture led to changes in precursor incorporation that were precursor and cell specific. The steroid significantly decreased the incorporation of 3H-glucosamine and increased the incorporation of 3H-proline in the outflow pathway cells and in the fibroblasts of the adjacent sclera. The specificity of the hormone effect was demonstrated by its inability to alter 3H-leucine incorporation. By contrast, in iridial fibroblasts dexamethasone caused a decreased incorporation of 3H-glucosamine while not affecting the incorporation of 3H-proline. Our results suggest that dexamethasone causes an increase in collagen synthesis in the target cells most closely related to the outflow pathway. Further, the decreased incorporation of 3H-glucosamine with dexamethasone suggests decreased synthesis of glycosaminoglycans, glycoproteins or possibly glycolipids in these same cells.

Glucocorticoid receptor binding in bovine lens.

The present study demonstrates glucocorticoid receptor localization in the nuclei of cells of the anterior epithelium and bow region and its absence in all other regions of the lens. Both autoradiographic and biochemical studies show that triamcinolone acetonide is inactive whereas tetrahydrocortisol (previously considered to be an inactive metabolite of cortisol) is an active competitor of dexamethasone binding to the glucocorticoid receptor in the bovine lens. The consistency of these findings by both techniques supports the validity of this observation. In addition, it indicates that autoradiography can be used for studying glucocorticoid agonist/antagonist relationships in the human lens, where only small amounts of tissue are available.

Specific estrogen receptors in human gingiva.

The cytoplasm of normal human male and female gingiva contains a receptor capable of specifically binding 17 beta-estradiol and moxestrol (R-2858) with high affinity (Kd = approximately 3.4 X 10(-10) M) and low capacity (4.5 fmol/mg protein). The binding is sensitive to heat (destroyed by warming to 37 C for 60 min), proteolytic enzymes (pronase, trypsin, and chymotrypsin), and exhibits a pattern of competition similar to that obtained with estrogen receptors from other target tissues. Nuclear uptake of [3H]estradiol was demonstrated by using a dry autoradiographic technique. Specific nuclear localization of [3H]estradiol was found predominantly in basal and spinous layers of gingival epithelium, stromal connective tissue cells (fibroblasts), and endothelial cells and pericytes of small blood vessels in the lamina propria. There was no difference between the Kd values in normal and diseased tissue or between the Kd values or number of binding sites and the age or sex of the patient. However, there was a difference between the amount of estrogen binding sites per mg protein in normal tissue compared to gingiva with dilantin hyperplasia. These results provide the first direct evidence that human gingiva may function as a target organ for estrogens.

Corneal-conjunctival uptake of topical 3H-dexamethasone in the rabbit eye.

Topically administered 3H-dexamethasone was localized radioautographically to the nuclei of several cell types in the cornea and conjunctiva. In the cornea, label was found in the epithelium and keratocytes. In the conjunctiva, label was found in the epithelium and in the connective tissue cells and blood vessel endothelial cells of the stroma. Prior administration of a 350-fold excess of nonlabeled hormone completely suppressed this localization, indicating that these cells are specific glucocorticoid target cells. There was no localization found in the corneal endothelium. Accumulation of silver grains between corneal stroma and Descemet's membrane suggests that this membrane acts as a partial barrier to diffusion of the steroid.

[IgG determination in the cerebrospinal fluid--correlation of these results with other cerebrospinal fluid values]. / Zur quantitativen IgG-Bestimmung im Liquor cerebrospinalis--Korrelation der Ergebnisse zu anderen Liquorwerten.

IgG determined by means of quantitative radial immunodiffusion in the cerebrospinal fluid of 225 neurological patients correlates in a statistically significant manner (p less than 0.001) with the gamma-globulin determined by the acetate foil electrophoresis. The indication of the IgG as a percentage of the total protein (limiting value of 10 per cent) is suitable for an orientating assessment in the diagnosis of inflammatory-immunoreactive diseases of the central nervous system. The IgG-values exceeding 10 per cent of the total protein correlate in 260 fluids examined in the respect with the percental value of the lymphocyte content which also lies above the reference range (p less than 0.001). For the assessment of the presence of a barrier disturbance, a comparison with the serum values should be carried out, either in the form of the frequently used fluid/serum quotients of the immunglobulin or the electrophoretically separated protein fraction.

Radioautography of dexamethasone in rabbit gingiva and buccal mucosa.

The localization of 3H-dexamethasone in gingiva and in buccal mucosa was investigated radioautographically after systemic administration of the labeled glucocorticoid to rabbits. Tissue samples were processed for dry radioautography of diffusible substances. This study demonstrates localization of 3H-dexamethasone in the nuclei of target cells in the gingival epithelium, stromata, and the walls of blood vessels, and to a lesser degree in the buccal mucosa cells. The findings support the possibility of a direct effect of glucocorticoids via specific hormone cytosol-nuclear receptors in oral tissues.