Variation in Bentgrass Susceptibility to Typhula incarnata and in Isolate Aggressiveness Under Controlled Environment Conditions

Typhula incarnata, the causal agent of gray snow mold, is an important winter pathogen of turfgrasses in the northern United States. The relative susceptibility of cultivars of three bent-grass species (creeping, colonial, and velvet bentgrass) to Typhula incarnata and the aggressiveness of 15 T. incarnata isolates obtained from infected turfgrasses on golf courses in Michigan, Minnesota, and Wisconsin were evaluated under controlled conditions. A hypersensitive type of resistance response to T. incarnata was not observed in any cultivar. Disease severity increased with higher inoculum concentration of T. incarnata. Colonization by gray snow mold gradually decreased with increasing plant age from 11 weeks after seeding in most cultivars tested, suggesting that age-related resistance was expressed over time. There were significant differences in disease severity among the three bentgrass species, particularly between tetraploid (creeping and colonial) and diploid (velvet) species, and among cultivars within each species, indicating varying levels of susceptibility to T. incarnata. All 15 isolates were pathogenic on bentgrass and were significantly different in aggressiveness, but aggressiveness was not related to geographic origin. Therefore, turfgrass breeders should be able to use one or a few virulent representative isolates of the pathogen to screen for resistance.

Biofilm formation by and antifungal susceptibility of Candida isolates from urine

Biofilm formation (BF) in the setting of candiduria has not been well studied. We determined BF and MIC to antifungals in Candida spp. isolates grown from urine samples of patients and performed a retrospective chart review to examine the correlation with risk factors. A total of 67 Candida spp. isolates were grown from urine samples from 55 patients. The species distribution was C. albicans (54%), C. glabrata (36%), and C. tropicalis (10%). BF varied greatly among individual Candida isolates but was stable in sequential isolates during chronic infection. BF also depended on the growth medium and especially in C. albicans was significantly enhanced in artificial urine (AU) compared to RPMI medium. In nine of the C. albicans strains BF was 4- to 10-fold higher in AU, whereas in three of the C. albicans strains and two of the C. glabrata strains higher BF was measured in RPMI medium than in AU. Determination of the MICs showed that planktonic cells of all strains were susceptible to amphotericin B (AMB) and caspofungin (CASPO) and that three of the C. glabrata strains and two of the C. albicans strains were resistant to fluconazole (FLU). In contrast, all biofilm-associated adherent cells were resistant to CASPO and FLU. The biofilms of 14 strains (28%) were sensitive to AMB (MIC(50) of <1 mug/ml). Correlation between degree of BF and MIC of AMB was not seen in RPMI grown biofilms but was present when grown in AU. A retrospective chart review demonstrated no correlation of known risk factors of candiduria with BF in AU or RPMI. We conclude that BF is a stable characteristic of Candida strains that varies greatly among clinical strains and is dependent on the growth medium. Resistance to AMB is associated with higher BF in AU, which may represent the more physiologic medium to test BF. Future studies should address whether in vitro BF can predict treatment failure in vivo.

Rise and fall time behavior of the gyrotron backward-wave oscillator

The rise and fall time behavior of a pulsed microwave oscillator is a problem of academic interest. It is also of importance to radar and other applications because it can lead to phase and frequency jitters or even lock the entire pulse into an undesired mode. Here we present a study of the rise and fall time behavior in the gyrotron backward-wave oscillator (gyro-BWO). Single-mode simulations reveal that, during the rise and fall portions of the electron beam pulse, oscillation frequencies of the axial modes vary in such a way that their transit angles remain at the respective optimum values. Thus, axial mode competition and mode switching can readily take place in these transient stages. Time-dependent simulations demonstrate that, under both the gradual and instant turn-on conditions, the axial modes compete in a pattern governed by the characteristic asymmetry of the mode profiles. Other aspects of physics interest include the analysis and explanation of a resultant hysteresis effect between the rise and fall portions of the beam pulse. These understandings are expected to provide the basis for achieving a stable gyro-BWO operating at a single mode throughout the entire beam pulse.

Transition of absolute instability from global to local modes in a gyrotron traveling-wave amplifier

The gyrotron traveling-wave amplifier employing the distributed-loss scheme is capable of very high gain and effective in suppressing the global absolute instabilities. This study systematically characterizes the local absolute instabilities and their transitional behavior. The local absolute instabilities are analyzed using a model that incorporates the penetration of the field from the copper section into the lossy section. The axial modes were characterized from the perspective of beam-wave interaction and were found to share many characteristics with the global modes. The transition from global modes to local modes as the distributed loss increases was demonstrated. The electron transit angle in the copper section, which determines the feedback criterion, governs the survivability of an oscillation. In addition, the oscillation thresholds predicted using this model are more accurate than those obtained using a simplified model.

Aggressiveness of Typhula ishikariensis Isolates to Cultivars of Bentgrass Species (Agrostis spp.) Under Controlled Environment Conditions

Speckled snow mold, caused by Typhula ishikariensis, is one of the most important Typhula snow molds in subarctic zones of the Northern Hemisphere. Nine isolates of three T. ishikariensis varieties (var. ishikariensis, var. canadensis, and var. idahoensis) isolated from infected turfgrasses on golf course fairways throughout Wisconsin were evaluated for their aggressiveness toward nine cultivars of three bentgrass species (three creeping, three colonial, and three velvet cultivars) under controlled environmental conditions. Speckled snow mold severity increased as inoculum concentration of T. ishikariensis was increased. In general, bentgrass susceptibility increased between 9 and 11 weeks after seeding but gradually decreased thereafter, suggesting expression of age-related resistance as plants matured. Significant differences in aggressiveness were detected within and among T. ishikariensis varieties. Significant interactions between T. ishikariensis varieties or isolates and bentgrass species were detected, but there was no interaction between pathogen isolates and bentgrass cultivars. Disease severity evaluations showed significant differences among bentgrass cultivars and species in their response to T. ishikariensis. Since bentgrass species exhibit differential responses to T. ishikariensis varieties, representative isolates of each variety should be employed for screening of bentgrass germplasm for resistance to speckled snow mold.

SUV in pelvic lymph node is a significant prognostic factor in previously untreated squamous carcinoma of the uterine cervix

5051

Background: The aim of this prospective study was to identify prognostic factors (including 18F-fluorodeoxyglucose positron emission tomography [FDG-PET] parameters) in previously untreated squamous carcinoma of the uterine cervix with MRI- or CT-defined pelvic or para-aortic lymph node (PLN or PALN) metastasis. Methods: This study included pooled patients selected from two prospective studies who had untreated squamous cell cervical cancer and PLN or PALN metastasis (diagnostic score 3 or 4) by CT-MRI and additional FDG-PET scans were performed for primary staging. Recurrence-free and overall survivals (RFS and OS) were evaluated using the Kaplan-Meier method. Prognostic variables were assessed by the log-rank test and Cox proportional hazards regression method. Optimal cut-offs of standardized uptake value (SUV) in primary tumor, PLN and PALN were determined by receiver operating characteristic and area under the curve analysis. Results: A total of 70 patients were eligible for analysis. The follow-up time ranged 16–59 months (mean ± SD: 38 ± 18). In univariate analyses, FIGO stage ≥ III, PET defined bilateral PLN-positive, PET defined PLN-positive, PET defined PALN-positive and SUV cut-off of 3.04 at PLN and 4.18 at PALN were significant for RFS. FIGO stage ≥ III, SUV cut-offs of 2.94–3.15 at PLN and SUV cut-offs of 2.61–4.91 at PALN were significant for OS. Multivariate analysis showed only SUVmax cut-off of 3.04 at PLN was a significant adverse factors for RFS (RR: 10.1 95% CI 2.2–46.0; P = 0.003) and OS (RR: 11.7 95% CI 1.5–92.6; P = 0.019), while SUVmax cut-off of 4.18 at PALN (P = 0.062) was marginally significant for OS. Conclusions: SUVmax cut-off of 3.04 at PLN was a significant adverse factor for RFS and OS in previously untreated squamous carcinoma of the uterine cervix with MRI- or CT-defined PLN or PALN metastasis.

No significant financial relationships to disclose.

Sequential antibodies to potassium channels and glutamic acid decarboxylase in neuromyotonia

A patient with thymoma-associated neuromyotonia and voltage-gated potassium channel (Kv1.2 and Kv1.6) antibodies by immunoprecipitation and rat brain immunolabeling was treated successfully with immunoadsorption and cyclophosphamide. Curiously, glutamic acid decarboxylase antibodies, absent at onset, appeared later. Stiff-person syndrome was absent, but fast blink reflex recovery suggested enhanced brainstem excitability. The range of antibodies produced in thymoma-associated neuromyotonia is richer, and the timing of antibody appearance more complex, than previously suspected.

Dynamics of mode competition in the gyrotron backward-wave oscillator

The axial modes of the gyrotron backward-wave oscillator (gyro-BWO) each exhibit a distinctive asymmetry in axial field profile. As a result, and in sharp contrast to the behavior of the familiar resonator-based gyrotron oscillator, particle simulations of the gyro-BWO reveal a radically different pattern of mode competition in which a fast-growing and well-established mode is subsequently suppressed by a later-starting mode with a more favorable field profile. This is verified in a Ka-band experiment and the interaction dynamics are elucidated with a time-frequency analysis.

Linkage map construction in allotetraploid creeping bentgrass (Agrostis stolonifera L.)

Creeping bentgrass (Agrostis stolonifera L.) is one of the most adapted bentgrass species for use on golf course fairways and putting greens because of its high tolerance to low mowing height. It is a highly outcrossing allotetraploid species (2n=4x=28, A(2) and A(3) subgenomes). The first linkage map in this species is reported herein, and it was constructed based on a population derived from a cross between two heterozygous clones using 169 RAPD, 180 AFLP, and 39 heterologous cereal and 36 homologous bentgrass cDNA RFLP markers. The linkage map consists of 424 mapped loci covering 1,110 cM in 14 linkage groups, of which seven pairs of homoeologous chromosomes were identified based on duplicated loci. The numbering of all seven linkage groups in the bentgrass map was assigned according to common markers mapped on syntenous chromosomes of ryegrass and wheat. The number of markers linked in coupling and repulsion phase was in a 1:1 ratio, indicating disomic inheritance. This supports a strict allotetraploid inheritance in creeping bentgrass, as suggested by previous work based on chromosomal pairing and isozymes. This linkage map will assist in the tagging and eventually in marker-assisted breeding of economically important quantitative traits like disease resistance to dollar spot (Sclerotinia homoeocarpa F.T. Bennett) and brown patch (Rhizoctonia solani Kuhn).

Chromosomal rearrangements differentiating the ryegrass genome from the Triticeae, oat, and rice genomes using common heterologous RFLP probes

An restriction fragment length polymorphism (RFLP)-based genetic map of ryegrass (Lolium) was constructed for comparative mapping with other Poaceae species using heterologous anchor probes. The genetic map contained 120 RFLP markers from cDNA clones of barley (Hordeum vulgare L.), oat (Avena sativa L.), and rice (Oryza sativa L.), covering 664 cM on seven linkage groups (LGs). The genome comparisons of ryegrass relative to the Triticeae, oat, and rice extended the syntenic relationships among the species. Seven ryegrass linkage groups were represented by 10 syntenic segments of Triticeae chromosomes, 12 syntenic segments of oat chromosomes, or 16 syntenic segments of rice chromosomes, suggesting that the ryegrass genome has a high degree of genome conservation relative to the Triticeae, oat, and rice. Furthermore, we found ten large-scale chromosomal rearrangements that characterize the ryegrass genome. In detail, a chromosomal rearrangement was observed on ryegrass LG4 relative to the Triticeae, four rearrangements on ryegrass LGs2, 4, 5, and 6 relative to oat, and five rearrangements on ryegrass LGs1, 2, 4, 5, and 7 relative to rice. Of these, seven chromosomal rearrangements are reported for the first time in this study. The extended comparative relationships reported in this study facilitate the transfer of genetic knowledge from well-studied major cereal crops to ryegrass.

Absolute instabilities in a high-order-mode gyrotron traveling-wave amplifier

The absolute instability is a subject of considerable physics interest as well as a major source of self-oscillations in the gyrotron traveling-wave amplifier (gyro-TWT). We present a theoretical study of the absolute instabilities in a TE01 mode, fundamental cyclotron harmonic gyro-TWT with distributed wall losses. In this high-order-mode circuit, absolute instabilities arise in a variety of ways, including overdrive of the operating mode, fundamental cyclotron harmonic interactions with lower-order modes, and second cyclotron harmonic interaction with a higher-order mode. The distributed losses, on the other hand, provide an effective means for their stabilization. The combined configuration thus allows a rich display of absolute instability behavior together with the demonstration of its control. We begin with a study of the field profiles of absolute instabilities, which exhibit a range of characteristics depending in large measure upon the sign and magnitude of the synchronous value of the propagation constant. These profiles in turn explain the sensitivity of oscillation thresholds to the beam and circuit parameters. A general recipe for oscillation stabilization has resulted from these studies and its significance to the current TE01 -mode, 94-GHz gyro-TWT experiment at UC Davis is discussed.

Characterization of Porcine Leptin Receptor Polymorphisms and Their Association with Reproduction and Production Traits

Fatness in pigs is of prime economic importance due to market incentives for production of lean pork and elevated fatness increasing the feed costs. Leptin (LEP) action, mediated through its specific receptors (LEPR), was reported to be involved in the regulation of fatness via feed intake, energy expenditure, and whole-body energy balance in pigs. In this study, we have designed 17 primer sets based on the human and mouse LEPR sequences and successfully amplified coding regions of 15 porcine LEPR exon fragments by polymerase chain reactions (PCR). Four single nucleotide polymorphisms (SNP) of Intron 2, Exons 2, 6, and 18 were found in Landrace, Yorkshire, and Duroc by mutagenetically separated-PCR (MS-PCR) and PCR-restriction fragment length polymorphisms (PCR-RFLP). Chi-square statistics was used to calculate homogeneity of genotypic frequencies of 4 gene polymorphisms for three breeds of animals. Effects of Intron 2, Exon 2, and Exon 18 polymorphisms on the reproduction trait such as litter sizes of sows were evident (p < 0.05) in Duroc and Yorkshire. There was no (p > 0.05) significant influence on the production trait of average daily gain due to four candidate gene polymorphisms in three porcine breeds. However, effects of Exon 6 and 18 polymorphisms on the production trait of backfat thickness were significant (p < 0.05) in Landrace and Yorkshire, respectively. Effects of Exon 18 polymorphisms on feed efficiency were also evident (p < 0.05) in Duroc.

Distinct effects of the antiestrogen Faslodex on the stability of estrogen receptors-alpha and -beta in the breast cancer cell line MCF-7

The effects of estrogen receptor (ER) ligands on the stability and transcriptional activity of ERbeta in the breast cancer cell lines MCF-7 and HeLa were examined. We found that ERbeta was degraded in the presence of 17beta-estradiol. Tamoxifen and Faslodex (ICI 182,780) prevented ERbeta receptor destabilization. In contrast to ERalpha, ERbeta degradation was not abolished by inhibitors of the proteasome-mediated protein degradation pathway. Furthermore, single point mutations in helix 12 of the receptor dramatically affected the stability and subsequent transcriptional activation of ERbeta.

Fermentation Acids, Aerobic Fungal Growth, and Intake of Napiergrass Ensiled with Nonfiber Carbohydrates

This study evaluated fermentation characteristics and fungal numbers of napiergrass silages prepared with and without added raw or heated corn meal (10%, fresh-weight basis) at ensiling. Corn was added to napiergrass so that the silage would contain concentrate similar to that of corn silage with minimum grain content. The silages treated with raw or heated corn were fed to dairy does to compare voluntary silage consumption. After 8 wk of fermentation, pH for silage treated with heated corn was lowest, and that for napiergrass ensiled alone was highest among the treatments. The addition of corn increased lactic acid, but propionic and butyric acids were also elevated. Acetic acid decreased in response to the supplementation of corn but remained the dominant acid for all silages. Numbers of fungi (yeasts plus molds) in silages did not differ significantly at silo opening or after 24 h of exposure to air. However, the numbers of fungi at 48 h in aerated silages containing corn were lower than were the fungi counts in the control silage. When the silages were offered free choice along with concentrate at a fixed rate, dairy does tended to consume more silage treated with heated corn than raw corn. Whole-tract nutrient digestibility and serum glucose and urea N were not altered. These results indicate that the addition of either raw or heated corn meal to napiergrass at ensiling was beneficial to silage fermentation quality because it decreased pH, increased lactic acid, and apparently suppressed fungal populations via elevated antifungal acids. A further advantage of heated corn vs. raw corn was increased silage intake.

Effect of Lasalocid on Growth, Blood Gases, and Nutrient Utilization in Dairy Goats Fed a High Forage, Low Protein Diet

This study investigated the effect of lasalocid on weight gain, blood gases, nutrient digestibility, and nitrogen utilization in growing dairy goats. In a growth experiment, 24 crossbred dairy does were assigned to diets without or with lasalocid (approximately 30 mg per head per day) for 12 wk. Goats were group fed bermudagrass hay for free choice plus concentrate at a fixed level (approximately 0.264 kg DM per head per d). Goats grew faster when fed lasalocid than those fed the control diet. Jugular blood partial pressure of O2 was lower when goats were supplemented with lasalocid. In contrast, goats fed lasalocid tended to have a higher partial pressure of CO2 than control goats. Percent O2 saturation tended to increase, and concentrations of total CO2 tended to decrease in goats fed lasalocid. Serum glucose and urea N did not differ between treatments. In a metabolism experiment, 8 castrated male goats were fed hay and concentrate identical to those of the growth experiment to determine whole tract nutrient digestibility and N utilization. Lasalocid did not affect feed intake or nutrient digestion coefficients. Daily urinary N output was reduced by lasalocid supplementation. In spite of this, N retention was not significantly affected. With use of ionophore, the proportion of urinary N relative to digested N tended to decrease, and the retained N as a proportion of digested N tended to increase.

J/psi polarization in 800-GeV p-Cu interactions

We present measurements of the polarization of the J/psi produced in 800-GeV proton interactions with a copper target. Polarization of the J/psi is sensitive to the ccmacr; production and hadronization processes. A longitudinal polarization is observed at large x(F), while at small x(F) the state is produced essentially unpolarized or slightly transversely polarized. No significant variation of the polarization is observed versus p(T).

Cross-section measurement of charged-pion photoproduction from hydrogen and deuterium

We have measured the differential cross section for the gamman-->pi(-)p and gammap-->pi(+)n reactions at theta(c.m.)=90 degrees in the photon energy range from 1.1 to 5.5 GeV at Jefferson Lab (JLab). The data at E(gamma) greater, similar 3.3 GeV exhibit a global scaling behavior for both pi(-) and pi(+) photoproduction, consistent with the constituent counting rule and the existing pi(+) photoproduction data. Possible oscillations around the scaling value are suggested by these new data. The data show enhancement in the scaled cross section at a center-of-mass energy near 2.2 GeV. The cross section ratio of exclusive pi(-) to pi(+) photoproduction at high energy is consistent with the prediction based on one-hard-gluon-exchange diagrams.

Linear and time-dependent behavior of the gyrotron backward-wave oscillator

Formation of axial modes in the gyrotron backward-wave oscillator is examined in the perspective of optimum conditions for beam-wave interactions. Distinctive linear properties are revealed and interpreted physically. Nonlinear implications of these properties (specifically, the role of high-order axial modes) are investigated with time-dependent simulations. Nonstationary oscillations exhibit self-modulation behavior while displaying no evidence of axial mode competition. Reasons for the erratic frequency tuning are investigated and stable tuning regimes are identified as a remedy.

Visualization of new virus-like-particles in Trichomonas vaginalis

In the present work, we demonstrate virus-like particles (VLPs) with various morphological variations in Trichomonas vaginalis. The VLPs were distinct based on size, shape and electron density, with VLPs being either electron-dense or electron-lucent. We used electron microscopy thin sections of several T. vaginalis strains virus-infected, and also negative staining of fractions obtained after purification by CsCl buoyant density gradient centrifugation. The particles observed in fractions are identical to those previously described, but by thin sections, we found new forms. The shapes found were icosahedral, spherical and oblong, and the sizes varied from 33 to 120nm in diameter with the most common VLP being spherical and having a size range from 83 to 104nm. The VLPs were found in the cytoplasm closely associated with the Golgi complex, with some VLPs budding from the Golgi, and other VLPs were detected adjacent to the plasma membrane. Unidentified cytoplasmic inclusions were observed in the region close to the VLPs and Golgi. Clusters of the already described icosahedral virus were also observed in the cytoplasm, although less frequently. These results indicate that T. vaginalis organisms may be infected with different dsRNA viruses simultaneously.

Neural hormonal regulation of exocrine pancreatic secretion

Exocrine pancreatic secretion is regulated by hormone-hormonal and neural-hormonal interactions involving several regulatory peptides and neurotransmitter from the gut, the pancreas and the vagus nerve. The roles of the gastrointestinal peptides including secretin, CCK, neurotensin, motilin, PYY and pancreatic islet hormones including insulin, pancreatic polypeptide and somatostatin have been established. Interactions among secretin, CCK and neurotensin produce synergistic stimulatory effect. Motilin modulates the cyclic pattern of pancreatic secretion while local insulin provides a permissive role for the action of secretin and CCK at physiological concentration. Somatostatin, PYY and pancreatic polypeptide are inhibitory regulators, acting either on the release of secretin and CCK or on the action of the two stimulatory hormones. The vagal afferent-efferent pathway mediates the actions of many of these regulatory peptides, particularly of secretin and CCK. Acetylcholine and nitric oxide are the neurotransmitters known to mediate the actions of secretin and CCK. Serotonin (5-HT) released from enterochromaffin cells in the intestinal mucosa and nerve terminals of the enteric nervous system and intrapancreatic nerves may be involved in both stimulatory and inhibitory mechanism through its various receptor subtypes. 5-HT also mediates the action of secretin and CCK. The regulatory roles of neuropeptides, PACP and GRP, are now established, whereas those of others are being uncovered. Pancreatic juice provides both positive and negative feedback regulation of pancreatic secretion through mediation of both secretin- and CCK-releasing peptides. Three CCK-releasing peptides have been purified: monitor peptide from pancreatic juice, diazepam-binding inhibitor from porcine intestine, and luminal CCK-releasing factor from rat intestinal secretion. All have been shown to stimulate CCK release and pancreatic enzyme secretion. Pancreatic phospholipase A2 from pancreatic juice and intestinal secretion appears to function as a secretin-releasing peptide. However, the detailed map of neurohormonal regulatory pathways of exocrine pancreatic secretion is yet to be constructed.

Measurement of G(E(p))/G(M(p)) in e(-->)p---> e(-->)p to Q(2) = 5.6 GeV(2)

The ratio of the electric and magnetic form factors of the proton G(E(p))/G(M(p)), which is an image of its charge and magnetization distributions, was measured at the Thomas Jefferson National Accelerator Facility (JLab) using the recoil polarization technique. The ratio of the form factors is directly proportional to the ratio of the transverse to longitudinal components of the polarization of the recoil proton in the elastic e(-->)p---> e(-->)p reaction. The new data presented span the range 3.5< Q(2)< 5.6 GeV(2) and are well described by a linear Q(2) fit. Also, the ratio sqrt[Q(2)] F(2(p))/F(1(p)) reaches a constant value above Q(2) = 2 GeV(2).

Dpp and Hh signaling in the Drosophila embryonic eye field

We have analyzed the function of the Decapentaplegic (Dpp) and Hedgehog (Hh) signaling pathways in partitioning the dorsal head neurectoderm of the Drosophila embryo. This region, referred to as the anterior brain/eye anlage, gives rise to both the visual system and the protocerebrum. The anlage splits up into three main domains: the head midline ectoderm, protocerebral neurectoderm and visual primordium. Similar to their vertebrate counterparts, Hh and Dpp play an important role in the partitioning of the anterior brain/eye anlage. Dpp is secreted in the dorsal midline of the head. Lowering Dpp levels (in dpp heterozygotes or hypomorphic alleles) results in a ‘cyclops’ phenotype, where mid-dorsal head epidermis is transformed into dorsolateral structures, i.e. eye/optic lobe tissue, which causes a continuous visual primordium across the dorsal midline. Absence of Dpp results in the transformation of both dorsomedial and dorsolateral structures into brain neuroblasts. Regulatory genes that are required for eye/optic lobe fate, including sine oculis (so) and eyes absent (eya), are turned on in their respective domains by Dpp. The gene zerknuellt (zen), which is expressed in response to peak levels of Dpp in the dorsal midline, secondarily represses so and eya in the dorsomedial domain. Hh and its receptor/inhibitor, Patched (Ptc), are expressed in a transverse stripe along the posterior boundary of the eye field. As reported previously, Hh triggers the expression of determinants for larval eye (atonal) and adult eye (eyeless) in those cells of the eye field that are close to the Hh source. Eya and So, which are induced by Dpp, are epistatic to the Hh signal. Loss of Ptc, as well as overexpression of Hh, results in the ectopic induction of larval eye tissue in the dorsal midline (cyclopia). We discuss the similarities between vertebrate systems and Drosophila with regard to the fate map of the anterior brain/eye anlage, and its partitioning by Dpp and Hh signaling.

Investigation and interpretation of band broadening in size exclusion chromatography

Study of Band Broadening occurring in Size Exclusion Chromatography (SEC) is reported using very narrow PS standards obtained and characterised by Temperature Gradient Interaction Chromatography (TGIC). Chromatograms are fitted by Exponentially Modified Gaussian functions (EMG) and mapping of band broadening is obtained for different column sets. Interpretation of the skewing of the chromatograms is proposed with a new model using Brownian motion properties inside the pores. That explains why band broadening and tailing become so important near total exclusion volume.

Liquid chromatography at the critical condition for polyisoprene using a single solvent

Liquid chromatography at the chromatographic critical condition has drawn much attention as an attractive characterization method of block copolymers since it has been proposed that a part of a polymer chain becomes "chromatographically invisible" at this condition, which would permit the characterization of individual blocks. A critical condition for a polymer species has been commonly established by use of mixed-solvent systems. It is not easy, however, to reproduce the critical condition since the retention of polymers depends very sensitively on the solvent composition and purity. Furthermore, the preferential sorption of a component in a mixed solvent may cause an additional problem. Therefore, the use of a single solvent is highly desirable to improve the reproducibility as well as the repeatability. In this study, a single-solvent critical condition for polyisoprene was established with 1,4-dioxane and C18 bonded silica as the mobile and stationary phases, respectively. At this condition, the "chromatographic invisibility" of polystyrene-polyisoprene diblock copolymers was critically examined and it was found that a rigorous chromatographic invisibility was not achieved and the retention of the block copolymers was affected by the length of the blocks under the critical condition. Some other chromatographic applications using the single-solvent system are also reported.

Characterization of stationary and nonstationary behavior in gyrotron oscillators

The transition from the stationary state to a sequence of nonstationary states in the gyromonotron oscillator is experimentally characterized for the first time. We have also demonstrated the stationary operation of a gyrotron backward-wave oscillator at a beam current far in excess of the generally predicted nonstationary threshold. This difference in nonlinear behavior has been investigated and shown to be fundamental with a comparative analysis of the feedback mechanisms, energy deposition profiles, and field shaping processes involved in these two types of oscillations.

Primary tumour volume delineation in nasopharyngeal carcinoma and correlation with 1997 AJCC tumour stage classification

OBJECTIVE

To investigate the variability in primary tumour volume in nasopharyngeal carcinoma and compare it with the tumour staging of the 1997 American Joint Committee on Cancer.

DESIGN

Prospective study.

SETTING

Tertiary care centre.

METHOD

A series of 33 newly diagnosed patients who were treated with high-dose radiotherapy participated in the study.

MAIN OUTCOME MEASURES

Using computed tomographic scans, primary tumour volumes were measured using the summation-of-areas technique, and the variability in tumour volume was determined. The Mann-Whitney test was used for statistical analysis.

RESULTS

A large variation in primary tumour volume was observed, especially in advanced-stage cases.

CONCLUSIONS

Nasopharyngeal carcinoma shows considerable variability in primary tumour volume. Incorporation of primary tumour volume may lead to further refinement of the 1997 tumour staging system.

Does a reduction in family medicine clerkship time affect educational outcomes?

BACKGROUND AND OBJECTIVES

Little is known about the relationship between the length of a family medicine clerkship and its educational outcomes. After our family medicine clerkship time decreased from 6 weeks to 4 weeks in July 1997, we studied how this change in clerkship length affected educational outcomes.

METHODS

Educational outcomes for the 2-year periods before and after the change were examined and compared whenever possible. Outcome measurements included student ratings of different aspects of the clerkship and student performance on clerkship examinations.

RESULTS

Students' exposure to common clinical problems was unaffected by the change. For the 4-week clerkship, there was a slight increase in student ratings of the adequacy of number of patients seen, the opportunity to follow-up with patients, the ability to develop health promotion plans, and overall satisfaction. Because the combinations of examinations used differed each year, student performance on clerkship examinations could not be directly compared.

CONCLUSIONS

Educational outcomes of the 4-week clerkship were similar to the 6-week clerkship. A few key outcomes improved. Various curricular and structural changes instituted for the 4-week clerkship contributed to the stability in outcomes. Reports from other medical schools may give additional insight into understanding this relationship.

Characterization of poly(L-lactide)-block-poly(ethylene oxide)-block-poly(L-lactide) triblock copolymer by liquid chromatography at the critical condition and by MALDI-TOF mass spectrometry

Poly(L-lactide)-block-poly(ethylene oxide)-block-poly(L-lactide) triblock copolymers (PLLA-b-PEO-b-PLLA) were fractionated in terms of the number of LLA units by liquid chromatography at the critical condition (LCCC) of PEO block. The fractionated samples were identified using MALDI-TOF mass spectrometry. The dependence of the LCCC retention of the diblock and triblock copolymers on the degree of polymerization of PLLA block(s) follows Martin's rule very well. Unlike the case of PEO-b-PLLA diblock copolymer reported earlier (Lee, H.; et al. Macromolecules 1999, 32, 4143), however, a splitting of the elution peaks containing the same number of LLA units was found. The peak splitting was ascribed to the different length distributions of PLLA blocks at the two ends of the PEO block. From the relative intensities of the peaks, the split peaks were assigned to different isomeric structures of the PLLA blocks. From these results we conclude that the interaction of the triblock copolymers with the stationary phase is affected by the distribution of the interacting blocks at the two ends of the center PEO block, in addition to the total number of LLA units in the triblock copolymer.

Polarization measurements in high-energy deuteron photodisintegration

We present measurements of the recoil proton polarization for the d(gamma-->,p-->)n reaction at straight theta(c.m.) = 90 degrees for photon energies up to 2.4 GeV. These are the first data in this reaction for polarization transfer with circularly polarized photons. The induced polarization p(y) vanishes above 1 GeV, contrary to meson-baryon model expectations, in which resonances lead to large polarizations. However, the polarization transfer Cx does not vanish above 1 GeV, inconsistent with hadron helicity conservation. Thus, we show that the scaling behavior observed in the d(gamma,p)n cross sections is not a result of perturbative QCD. These data should provide important tests of new nonperturbative calculations in the intermediate energy regime.

Observation of polarization in bottomonium production at square root of s = 38.8 GeV

We present a measurement of the polarization observed for bottomonium states produced in p-Cu collisions at square root of s = 38.8 GeV. The angular distribution of the decay dimuons of the Upsilon(1S) state shows no polarization at small values of the fractional longitudinal momentum x(F) and transverse momentum p(T) but significant positive transverse production polarization for either p(T)>1.8 GeV/c or for x(F)>0.35. The Upsilon(2S+3S) (unresolved) states show a large transverse production polarization at all values of x(F) and p(T) measured. These observations challenge NRQCD calculations of the polarization expected in the hadronic production of bottomonium states.

Characterization of polystyrene and polyisoprene by normal-phase temperature gradient interaction chromatography

Temperature gradient interaction chromatography (TGIC) is applied to the characterization of polyisoprene (PI) and polystyrene (PS) using normal-phase (NP) stationary phase--bare silica or diol bonded silica. Tetrahydrofuran-isooctane mixtures are used as a mobile phase. PI and linear and star shaped PS samples are successfully fractionated in terms of the molecular mass with a high resolution comparable to that of reversed-phase (RP) HPLC. Temperature dependence of the retention shows that the enthalpy of adsorption of PS to the stationary phase is exothermic. In addition, some characteristic features of the NP-TGIC system relative to those of RP-TGIC are presented, which include a high sensitivity on the polar end group and the simultaneous size-exclusion chromatographic and TGIC characterization of PS and PI mixtures.

Glutamine ameliorates mechanical obstruction-induced intestinal injury

BACKGROUND

Glutamine has been shown to be an important dietary component for the maintenance of gut integrity. Although considered a nonessential amino acid in normal circumstances, glutamine may become conditionally essential for the bowel during episodes of severe illness and malnutrition. In this study, we employed an animal model simulating mechanical intestinal obstruction to explore the beneficial effects of glutamine on the intestine in response to obstruction-induced injury.

MATERIALS AND METHODS

Rats were on three feeding regimens-standard diet and water (control group), diet and water containing 2% glutamine (glutamine group), or diet and water containing 2% arginine (arginine group)-for 3 days prior to surgical preparation of intestinal obstruction. The bowel distension, fluid accumulation, and histological alterations in the intestinal mucosa were measured 40 h after ileal ligation.

RESULTS

After 3 days of drinking water intervention, the plasma glutamine levels in the glutamine group (677 +/- 12 microM) were higher than those in the control (451 +/- 27 microM) and arginine (379 +/- 25 microM) groups. The distension ratio measured 40 h after ileal ligation was significantly lower in the glutamine group (30.9 +/- 4.2%) than in the control and arginine groups (45.9 +/- 1.7 and 46.1 +/- 3.4%, respectively). Also, glutamine markedly decreased the fluid accumulation in the obstructed bowel segment (control group, 178.41 +/- 18.60 mg/cm; glutamine group, 104.97 +/- 13.17 mg/cm; arginine group, 141.4 +/- 12.85 mg/cm). Furthermore, the obstruction-induced mucosal injury was substantially improved in glutamine-fed rats.

CONCLUSIONS

Our findings indicate that glutamine can significantly reduce the degree of those physiological derangements induced by mechanical intestinal obstruction.