bluuebunny/crossref_metadata_2025 huggingface dataset:
High-resolution direct-write multiphoton photolithography in poly(methylmethacrylate) films
Authors: Higgins Daniel A. , Everett Thomas A. , Xie Aifang , Forman Sarah M. , Ito Takashi
Published: May 2006

Multiphoton photolithography in poly(methylmethacrylate) films is demonstrated. High-resolution structures of arbitrary geometry with edge sharpnesses as small as 120nm are produced using femtosecond pulses of 870nm light focused to a diffraction-limited spot in the films. The power dependence of etching and tests of different polymers prove that the process is nonlinear and involves excitation of the polymer’s chromophores. Atomic force microscopy images show that the vast majority of polymer is removed during etching. It is concluded that the etching mechanism involves depolymerization and thermal evaporation of the polymer. Application of this method in the fabrication of electrochemical microelectrodes is demonstrated.
Soft x-ray polarizer for optical productions of any orthogonal state of the linear and circular polarization modes
Authors: Jeong Dae-Eun , Lee Ki-Suk , Kim Sang-Koog
Published: May 2006

An efficient soft x-ray polarizer that is able to optically convert a linear polarization state to any orthogonal state of not only linear but also circular polarization modes is found by means of numerical calculations of the intensities of individual orthogonal polarization components in reflected waves. Calculation results, using the known linear-polarization-mode based Kerr matrix as well as a newly derived circular-polarization-mode based Kerr matrix, indicate that a +45° or −45° linearly polarized incident wave can be readily converted to any orthogonal states of both circular and linear polarization modes, i.e., left- and right-handed circular and s- and p-linear polarizations through reflection, at certain grazing angles of incidence near the critical angle from a simple ferromagnetic thin film of Co(9.0nm)∕Si substrate. The intensities of almost pure circularly or linearly polarized reflected waves are about 10% or less in a certain spectral soft x-ray range just below the absorption edges of constituent magnetic elements. The counterpart orthogonal states of the linear as well as circular modes can be rapidly switched simply by reversing oppositely the orientation of longitudinal magnetizations. These results suggest that the orthogonal polarization states of the circular- and linear-polarization modes converted from such a polarizing optical element through reflection can be practically used in probing the vector quantities of element specific magnetizations in multicomponent magnetic materials.
Enhanced hard x-ray emission from microdroplet preplasma
Authors: Anand M. , Kahaly S. , Ravindra Kumar G. , Krishnamurthy M. , Sandhu A. S. , Gibbon P.
Published: May 2006

We perform a comparative study of hard x-ray emission from femtosecond laser plasmas in 15μm methanol microdroplets and Perspex target. The hard x-ray yield from droplet plasmas is ≃68 times more than that obtained from solid plasmas at 2×1015Wcm−2. A 10ns prepulse at about 5% of the main pulse appears to be essential for hard x-ray generation from droplets. Hot electron temperature of 36keV is measured from the droplets at 8×1014Wcm−2, whereas a three times higher intensity is needed to obtain similar hot electron temperatures from Perspex plasmas. Particle-in-cell simulations with very long scale-length density profiles support experimental observations.
Cyanogenesis in the Australian tropical rainforest endemic Brombya platynema (Rutaceae): chemical characterisation and polymorphism
Authors: Miller Rebecca E. , Simon Judy , Woodrow Ian E.
Published: May 2006

This study examined two aspects of cyanogenesis in Brombya platynema F. Muell. (Rutaceae), a subcanopy tree endemic to tropical rainforest in far north Queensland, Australia. First, cyanogenic glycosides in foliage were fractionated and identified. The rare meta-hydroxylated cyanogenic glycoside, holocalin, was identified as the principal cyanogen, and traces of prunasin and amygdalin were detected. This is the first characterisation of cyanogenic constituents within the genus, and to the authors’ knowledge, only the third within the Rutaceae, and the order Rutales. Second, variation in cyanogenic glycoside content within a population of B. platynema in lowland tropical rainforest was quantified. Both qualitative and quantitative polymorphism for cyanogenesis was identified. Interestingly, ~57% of individuals were considered acyanogenic, with concentrations of cyanogenic glycosides less than 8 μg CN g–1 DW. Among cyanogenic individuals there was substantial quantitative variation in cyanogenic glycoside concentration, which varied from 10.5 to 1285.9 μg CN g–1 DW. This high frequency of acyanogenic individuals is contrasted with the apparent absence of the acyanogenesis among populations of other tropical rainforest tree species. In the high herbivory environment of the tropical rainforest, this frequency of acyanogenesis among cyanogenic tropical tree taxa is unique.
Construction and characterization of infectious intragenotypic and intergenotypic hepatitis C virus chimeras
Authors: Pietschmann Thomas , Kaul Artur , Koutsoudakis George , Shavinskaya Anna , Kallis Stephanie , Steinmann Eike , Abid Karim , Negro Francesco , Dreux Marlene , Cosset Francois-Loic , Bartenschlager Ralf
Published: May 2006

Chronic liver disease caused by infection with hepatitis C virus (HCV) is an important global health problem that currently affects 170 million people. A major impediment in HCV research and drug development has been the lack of culture systems supporting virus production. This obstacle was recently overcome by using JFH1-based full-length genomes that allow production of viruses infectious both
in vitro
and
in vivo
. Although this improvement was important, because of the restriction to the JFH1 isolate and a single chimera consisting of J6CF and JFH1-derived sequences, broadly based comparative studies between different HCV strains were not possible. Therefore, in this study we created a series of further chimeric genomes allowing production of infectious genotype (GT) 1a, 1b, 2a, and 3a particles. With the exception of the GT3a/JFH1 chimera, efficient virus production was obtained when the genome fragments were fused via a site located right after the first transmembrane domain of NS2. The most efficient construct is a GT2a/2a chimera consisting of J6CF- and JFH1-derived sequences connected via this junction. This hybrid, designated Jc1, yielded infectious titers 100– to 1,000-fold higher than the parental isolate and all other chimeras, suggesting that determinants within the structural proteins govern kinetic and efficiency of virus assembly and release. Finally, we describe an E1-specific antiserum capable of neutralizing infectivity of all HCV chimeras.
Self-recognition, color signals, and cycles of greenbeard mutualism and altruism
Authors: Sinervo Barry , Chaine Alexis , Clobert Jean , Calsbeek Ryan , Hazard Lisa , Lancaster Lesley , McAdam Andrew G. , Alonzo Suzanne , Corrigan Gwynne , Hochberg Michael E.
Published: May 2006

Altruism presents a challenge to evolutionary theory because selection should favor selfish over caring strategies. Greenbeard altruism resolves this paradox by allowing cooperators to identify individuals carrying similar alleles producing a form of genic selection. In side-blotched lizards, genetically similar but unrelated blue male morphs settle on adjacent territories and cooperate. Here we show that payoffs of cooperation depend on asymmetric costs of orange neighbors. One blue male experiences low fitness and buffers his unrelated partner from aggressive orange males despite the potential benefits of defection. We show that recognition behavior is highly heritable in nature, and we map genetic factors underlying color and self-recognition behavior of genetic similarity in both sexes. Recognition and cooperation arise from genome-wide factors based on our mapping study of the location of genes responsible for self-recognition behavior, recognition of blue color, and the color locus. Our results provide an example of greenbeard interactions in a vertebrate that are typified by cycles of greenbeard mutualism interspersed with phases of transient true altruism. Such cycles provide a mechanism encouraging the origin and stability of true altruism.
Requirement of Rac1 in the development of cardiac hypertrophy
Authors: Satoh Minoru , Ogita Hisakazu , Takeshita Kyosuke , Mukai Yasushi , Kwiatkowski David J. , Liao James K.
Published: May 2006

The development of cardiac hypertrophy is mediated, in part, by increase in NADPH oxidase activity and myocardial oxidative stress. The Rho GTPase, Rac, regulates NADPH oxidase activity through interaction with gp91phoxand p67phox(in which “phox” is phagocyte oxidase). However, it is not known which Rac isoform mediates this effect in the heart. Here we show that Rac1 is critical for generating oxidative stress and producing cardiac hypertrophy in the adult heart. The Rac1 gene was temporally and specifically deleted in adult mouse cardiomyocytes (c-Rac1−/−). Compared with wild-type or Rac1 heterozygous mice, the hearts of c-Rac1−/−mice showed decreased gp91phoxand p67phoxinteraction, NADPH oxidase activity, and myocardial oxidative stress in response to angiotensin II (400 ng/kg per day for 2 weeks) stimulation. This result correlated with decreased myocardial hypertrophy. These results indicate that Rac1 is critical for the hypertrophic response in the heart and suggest that therapies which target myocardial Rac1 may be beneficial in the treatment of cardiac hypertrophy.
Tracking germinal center B cells expressing germ-line immunoglobulin γ1 transcripts by conditional gene targeting
Authors: Casola Stefano , Cattoretti Giorgio , Uyttersprot Nathalie , Koralov Sergei B. , Seagal Jane , Hao Zhenyue , Waisman Ari , Egert Angela , Ghitza Dvora , Rajewsky Klaus
Published: May 2006

Germinal centers (GCs) represent the main sites for the generation of high-affinity, class-switched antibodies during T cell-dependent antibody responses. To study gene function specifically in GC B cells, we generated Cγ1-cre mice in which the expression of Cre recombinase is induced by transcription of the Ig γ1 constant region gene segment (Cγ1). In these mice, Cre-mediated recombination at thefas,Igβ,IgH, andRosa26loci occurred in GC B cells as early as 4 days after immunization with T cell-dependent antigens and involved >85% of GC B cells at the peak of the GC reaction. Less than 2% of IgM+B cells showed Cre-mediated recombination. These cells carried few Ig somatic mutations, expressed germ-line Cγ1- and activation-induced cytidine deaminase-specific transcripts and likely include GC B cell founders and/or plasma cell precursors. Cre-mediated recombination involved most IgG1, but also a fraction of IgG3-, IgG2a-, IgG2b-, and IgA-expressing GC and post-GC B cells. This result indicates that a GC B cell can transcribe more than one downstream CHgene before undergoing class switch recombination. The efficient induction of Cre expression in GC B cells makes the Cγ1-cre allele a powerful tool for the genetic analysis of these cells, as well as, in combination with a suitable marker for Cre-mediated recombination, the tracking of class-switched memory B and plasma cellsin vivo. To expedite the genetic analysis of GC B cells, we have established Cγ1-cre F1embryonic stem cells, allowing further rounds of gene targeting and the cloning of compound mutants by tetraploid embryo complementation.
Visual search in children and adults: Top-down and bottom-up mechanisms
Authors: Donnelly Nick , Cave Kyle , Greenway Rebecca , Hadwin Julie A. , Stevenson Jim , Sonuga-Barke Edmund
Published: May 2006

Three experiments investigated visual search for targets that differed from distractors in colour, size, or orientation. In one condition the target was defined by a conjunction of these features, while in the other condition the target was the odd one out. In all experiments, 6–7- and 9–10-year-old children were compared with young adults. Experiment 1 showed that children's search differed from adults’ search in two ways. In conjunction searches children searched more slowly and took longer to reject trials when no target was present. In the odd-one-out experiments, 6–7-year-old children were slower to respond to size targets than to orientation targets, and slower for orientation targets than for colour targets. Both the other groups showed no difference in their rate of responding to colour and orientation. Experiments 2 and 3 highlighted that these results were not a function of either differential density across set sizes (Experiment 2) or discriminability of orientation and colour (Experiment 3). Across all three experiments, the results of both conjunction and odd-one-out searches highlighted a development in visual search from middle to late childhood.
Tuberculosis in Healthcare Workers at a General Hospital in Mexico
Authors: Laniado-Laborín Rafael , Cabrales-Vargas Noemí
Published: May 2006

Objective.

To determine the incidence rate of tuberculosis (TB) disease among healthcare workers (HCWs) at a general hospital.

Design.

Retrospective analysis of TB cases among HCWs over the course of 5 years.

Setting.

A 140-bed general hospital in Tijuana, Mexico.

Participants.

All hospital employees who developed TB during the 5-year period.

Results.

From 1 January 1999 through 31 December 2003, 18 TB cases were diagnosed among the hospital personnel. During that period, the mean ( ± standard deviation) annual work force of the hospital was 819 ± 21.7 employees. The TB incidence rate was 439.56 cases per 100,000 employees; this rate was 10.98 times higher than the rate for the general population of the city. The TB incidence rate for physicians was 860.21 cases per 100,000 employees, that for nurses was 365.85 cases per 100,000 employees, and that for physicians in training was 1,846.15 cases per 100,000 employees. Physicians in training had a higher risk of acquiring TB than did either physicians (relative risk, 2.14 [95% confidence interval, 1.34-35.66) or nurses (relative risk, 5.04 [95% confidence interval, 3.16-83.33). Three of the HCWs with TB disease were infected with a drug-resistant strain of Mycobacterium tuberculosis, and one of the infecting strains was multidrug resistant. Asymptomatic TB infection among HCWs was not addressed during this study.

Conclusions.

The TB incidence rate among the HCWs at the hospital is extremely high, compared with that in the general population. The implementation of infection control measures is an urgent priority, to reduce this occupational hazard.
Hospital Waste Generation During an Outbreak of Severe Acute Respiratory Syndrome in Taiwan
Authors: Chiang Chow F. , Sung Fung C. , Chang Fang H. , Tsai Ching T.
Published: May 2006

During the SARS outbreak in Taiwan, the number of ambulatory patients and inpatients treated at one medical center decreased by 40%-70% because of the increasing number of SARS patients. A the peak of the epidemic, the amount of hospital infectious waste had increased from a norm of 0.85 kg per patient-day to 2.7 kg per patient-day. However, the hospital was able to return the generation of waste to normal levels within 10 days.
Airborne Severe Acute Respiratory Syndrome Coronavirus Concentrations in a Negative-Pressure Isolation Room
Authors: Tsai Ying-Huang , Wan Gwo-Hwa , Wu Yao-Kuang , Tsao Kuo-Chien
Published: May 2006

This study used a sensitive polymerase chain reaction method coupled with filter sampling to detect the presence of airborne severe acute respiratory syndrome (SARS) coronavirus in an isolation patient room with a patient with severe acute respiratory syndrome receiving mechanical ventilatory support. Polymerase chain reaction results were negative for SARS coronavirus in room air both before and after patient extubation.
Screening for Tuberculosis Infection Using Whole-Blood Interferon-γ and Mantoux Testing Among Japanese Healthcare Workers
Authors: Harada Nobuyuki , Nakajima Yutsuki , Higuchi Kazue , Sekiya Yukie , Rothel Jim , Mori Toru
Published: May 2006

Objective.

To examine the hypothesis that results of the QuantiFERON-TB Gold assay (QFT-G), a whole-blood test for detection of tuberculosis infection, are more significantly related to known risk factors for tuberculosis infection in healthcare workers (HCWs) who have received bacille Calmette-Guerin vaccine than are results of the Mantoux tuberculin skin test (TST).

Design.

All HCWs (approximately 510) from a 370-bed general hospital in Tokyo where patients with and patients without tuberculosis are treated were invited to participate in the study. All study participants completed a questionnaire about their Mycobacterium tuberculosis infection risk factors as HCWs at the general hospital. They were then tested for LTBI by means of the QFT-G, followed by the TST. Statistical analyses were performed to compare results of each test with M. tuberculosis infection risk factors (age, length of employment in the healthcare industry, history of working with tuberculosis-positive patients in a tuberculosis ward or in the outpatient department of the hospital's tuberculosis clinic for more than 1 year, chest radiograph evidence of healed tuberculosis, history of performing bronchoscope procedures, and job classification), and for TST-positive HCWs, to compare the QFT-G result with the TST induration diameter.

Results.

A total of 332 HCWs (95% of whom had been vaccinated with BCG) participated in the study, and 33 had positive QFT-G results, suggesting a prevalence of LTBI of 9.9%. Of 304 HCWs who underwent TST, 283 (93.1%) had an induration diameter of 10 mm or more. Multiple logistic regression analysis revealed that positive QFT-G results were significantly associated with age and with a history of working in a tuberculosis ward or an outpatient department of a tuberculosis clinic. TST results were not correlated with any of the tuberculosis infection risk factors we evaluated.

Conclusions.

Positive QFT-G results were closely associated with the presence of risk factors for LTBI in a hospital setting, suggesting that the QFT-G can detect LTBI in a population composed predominately of BCG vaccinees. Because most HCWs worldwide have been vaccinated with BCG, the QFT-G offers a significant improvement over the TST in tuberculosis screening programs and minimizes un-warranted use of tuberculosis prophylaxis.
Prospective Surveillance Effectively Reduced Rates of Surgical Site Infection Associated With Elective Colorectal Surgery at a University Hospital in Japan
Authors: Konishi Tsuyoshi , Watanabe Toshiaki , Morikane Keita , Fukatsu Kazuhiko , Kitayama Joji , Umetani Naoyuki , Kishimoto Junji , Nagawa Hirokazu
Published: May 2006

At a university hospital in Japan, the introduction of prospective surveillance and subsequent interventions was effective in reducing the rate of surgical site infection associated with elective colorectal surgery from 27.5% to 17.8% of surgeries. Japan should both recognize the importance of broader surveillance for surgical site infection and establish its own nationwide surveillance database.
Tuberculosis in Healthcare Workers: A Molecular Epidemiologic Study in San Francisco
Authors: Ong Adrian , Rudoy Irina , Gonzalez Leah C. , Creasman Jennifer , Kawamura L. Masae , Daley Charles L.
Published: May 2006

Objective.

Healthcare workers (HCWs) are at risk of becoming infected with Mycobacterium tuberculosis through occupational exposure. To identify HCWs who became infected and developed tuberculosis as a result of their work, we studied the molecular epidemiology of tuberculosis in HCWs.

Design.

Eleven-year prospective cohort molecular epidemiology study.

Setting.

City and County of San Francisco, California.

Patients.

All persons reported with tuberculosis between 1993 and 2003. HCWs were identified from the San Francisco Tuberculosis Control Section's database, and mycobacterial isolates from culture-positive subjects were analyzed by IS6110-based genotyping. RESULTS. Of 2510 cases of tuberculosis reported during the study period, 31 (1.2%) occurred in HCWs: the median age of the HCWs was 37 years, and 11 (35%) were male. HCWs were more likely than non-HCWs to be younger (P= .0036), born in the United States (P= .0004), and female (P= .0003) and to not be homeless (P= .010). The rate of tuberculosis among HCWs remained constant during the study period, despite a significant decrease in the overall case rate in San Francisco. Work-related transmission was documented in at least 10 (32%) of 31 HCWs, including 4 of 8 HCWs whose isolates were part of genotypically determined clusters. Only 1 of 7 cases of tuberculosis in HCWs after 1999 was documented as being work related.

Conclusions.

Although most cases of tuberculosis in HCWs, as in non-HCWs, developed as a result of endogenous reactivation of latent infection, at least half of clustered cases of tuberculosis in HCWs were related to work. The number of work-related cases of tuberculosis in HCWs decreased during the study period.
Preoperative Low Molecular Weight Heparin as Venous Thromboembolism Prophylaxis in Patients at Risk for Prosthetic Infection After Knee Arthroplasty
Authors: Asensio Angel , Ramos Antonio , Múñez Elena , Vilanova José L. , Torrijos Pedro , Garcia Fernando J.
Published: May 2006

Objective:

To investigate the effect of preoperative initiation of low molecular weight heparin as prophylaxis for deep venous thrombosis in patients at risk of developing surgical-site infections after knee arthroplasty.

Design:

Case–control study nested in a cohort. The incidence of surgical-site infection in the cohort was calculated. With the use of data extracted from medical histories and after adjustment for other risk factors, the effect of preoperative heparinization on the risk of incisional and prosthetic infection among case-patients and control-patients (1:3 ratio) was assessed.

Setting:

Orthopedic department in a tertiary-care referral hospital.

Patients:

A cohort of 160 consecutive patients who had received prosthetic knee implants between October 1, 2001, and November 30, 2003.

Results:

Eighteen patients with surgical-site infections were identified, yielding an incidence of incisional and prosthetic infection of 6.9 (95% confidence interval [CI95], 3.5 to 12.0) and 4.4 (CI95,1.8 to 8.8) cases per 100 patients undergoing surgery, respectively. Surgical-site infection was associated with preoperative use of low molecular weight heparin (odds ratio [OR], 6.2 after adjustment for medical and surgical factors; CI95, 1.5 to 23). Prosthetic infection was strongly associated with preoperative use of prophylaxis (OR, undetermined [100% exposure in case-patients vs 35% exposure in control-patients];P= .002), but incisional surgical-site infection was not.

Conclusion:

The use of low molecular weight heparins immediately before knee arthroplasty as prophylaxis for deep venous thrombosis should be questioned because of probable increased risk of prosthetic infection.
A spatial analysis of small‐ and medium‐sized information technology firms in Canada and the importance of local connections to institutions of higher education
Authors: Meyer Stephen P.
Published: May 2006

As part of community/regional development policy, governments in Canada attempt to create conditions that stimulate the formation of high‐technology clusters and, in so doing, often encourage firm–university/college liaisons. Information technology (IT) is an important segment of the high‐technology sector, and small‐ and medium‐sized Canadian IT firms are disproportionately attracted to large metropolitan areas (with Toronto, Ottawa–Hull, Vancouver, Calgary, Montréal, Kitchener and Edmonton being the most noteworthy). A nearest neighbour analysis suggests that small‐ and medium‐sized IT firms are clustered within the metropolitan setting, and a nearest neighbour hierarchical spatial clustering technique demonstrates that intra‐urban IT agglomerations can be objectively identified. The linkages between small‐ and medium‐sized IT firms and higher education institutions are, on average, not strongly entrenched within Canada's IT culture, although many of these firms still connect with universities or colleges through co‐operative programs and other means of employee recruitment and via general networking with faculty members. Thus, governments may be able to support IT cluster formation by encouraging firm–university/college connections that centre on student participation.
Chylothorax as a complication of innominate vein thrombosis induced by a peripherally inserted central catheter
Authors: Wu E. T. , Takeuchi M. , Imanaka H. , Higuchi T. , Kagisaki K.
Published: May 2006

A 5‐month‐old boy with hypoplastic left heart syndrome developed chylothorax and oedema of the left upper arm more than 2 months after recovering from a Norwood stage II operation. Venography showed occlusion of the innominate vein with abundant collaterals crossing the midline to join the right internal jugular vein. The occlusion was caused by a peripherally inserted central catheter under systemic heparinisation. This case highlights the importance of a patent venous pathway, especially in patients with a cavopulmonary connection in the upper extremities.
High concentration potassium permanganate eliminates protein and particle contamination of the reusable Classic™ laryngeal mask airway
Authors: Laupau W. , Brimacombe J. , Richards E. , Keller C.
Published: May 2006

In this three‐stage study, we test the hypothesis that supplementary cleaning with potassium permanganate ≥4 mg.l−1 eliminates protein and particle contamination from the reusable Classic™ laryngeal mask airway. The first stage involved supplementary cleaning of 70 1 × 1 cm segments from deliberately contaminated laryngeal mask airways using potassium permanganate at 0, 2, 4, 8, 16, 32 and 64 mg.l−1 and testing for protein staining. This showed that the lowest concentration required to eliminate protein contamination was 8 mg.l−1. The second stage involved supplementary cleaning of 50 used laryngeal mask airways with either potassium permanganate 8 mg.l−1 or saline and testing for protein staining. This showed that protein contamination was lower in the potassium permanganate group (p < 0.00001): all laryngeal mask airways in the control group and none in the potassium permanganate group were contaminated. The third stage involved scanning electron microscopic examination of 1 × 1 cm segments from three laryngeal mask airways used in the control group, three from the potassium permanganate group, plus three brand new laryngeal mask airways. The mean density of ≥1 μm surface particles was lower in the potassium permanganate 8 mg.l−1 than the control group (21 vs. 121 .cm−2, p < 0.0001) and was similar to brand new laryngeal mask airways (24 .cm−2). We conclude that supplementary cleaning with potassium permanganate 8 mg.l−1 eliminates protein deposits from reusable laryngeal mask airways and reduces particle contamination to similar levels to brand new laryngeal mask airways.
Cardiac stem cell therapy: present and future
Authors: Saha Mrinal , Ferro Albert
Published: May 2006

The last decade has seen great strides in the drug treatment of myocardial infarction and consequent heart failure, with associated improvements in quality of life, haemodynamics and survival. Despite this, the benefits of pharmacotherapy are limited in the more severe cases, and mortality and morbidity remain high. The ability to replace damaged myocardium by the use of stem cell therapy offers a new and potentially exciting treatment modality, but its benefits are at present far from established. Here we briefly review the current state of cardiac stem cell therapy and consider its future.
Molecular weight and humification index as predictors of adsorption for plant‐ and manure‐derived dissolved organic matter to goethite
Authors: Ohno T. , Chorover J. , Omoike A. , Hunt J.
Published: May 2006

Sorptive retention of organic matter is important in maintaining the fertility and quality of soils in agricultural ecosystems. However, few sorption studies have been conducted that use dissolved organic matter (DOM) characteristic of agricultural amendments. We investigated the sorption to goethite (α‐FeOOH) of DOM extracted from: (i) above‐ground biomass of wheat straw (Triticum aestivum L.), maize residue (Zea mays L.), soybean residue (Glycine max (L.) Merr.), and hairy vetch residue (Vivia billosa L.); (ii) below‐ground biomass from maize, soybean, canola (Brassica napus L.), and green bean (Phaseolus vulgaris L.); and (iii) beef, dairy, poultry, and pig animal manures. The apparent molecular weight (MWAP) of the DOM was measured by high performance‐size exclusion chromatography and ranged from 312 to 1074 g mol−1. The carboxyl‐group content of the DOM measured by potentiometric titration ranged from 4.84 to 21.38 mmol(−) g−1 carbon. The humification index (HIX) determined by fluorescence spectrometry varied from 1.15 to 4.33. Sorption was directly related to both MWAP and HIX values of the DOM. Molecular weight analysis of the solution prior to and after sorption indicated that the DOM molecules > 1800 g mol−1 were preferentially sorbed, resulting in fractionation of the DOM upon reaction with goethite. The multiple regression equation, based only on MWAP and HIX parameters, explained 76% of the variance in amount of DOM sorbed. The results indicate that MWAP and HIX are important factors in controlling the sorption of DOM to mineral surfaces. Amendment with materials that release DOM of higher molecular weight and greater humification will result in enhanced initial sorption of DOM to soil solids, thereby contributing to accumulation of a larger soil organic C pool.
Adoptive T‐cell transfer in cancer immunotherapy
Authors: Tey Siok‐Keen , Bollard Catherine M , Heslop Helen E
Published: May 2006

Adoptive T‐cell therapy has definite clinical benefit in relapsed leukaemia after allogeneic transplant and in Epstein–Barr virus‐associated post‐transplant lymphoproliferative disease. However, the majority of tumour targets are weakly immunogenic self‐antigens and success has been limited in part by inadequate persistence and expansion of transferred T cells and by tumour‐evasion strategies. Adoptive immunotherapy presents the opportunity to activate, expand and genetically modify T cells outside the tolerising environment of the host and a number of strategies to optimize the cellular product, including gene modification and modulation of the host environment, in particular by lymphodepletion, have been developed.
Some considerations on the use of peptides and mRNA for therapeutic vaccination against cancer
Authors: Rammensee Hans‐Georg
Published: May 2006

Active immunization against existing cancer is a field that is currently in development and is associated with a number of problems. The potential use of peptides as minimal essential T‐cell antigens and of mRNA as a novel form of antigen with advantages is discussed, with special consideration of practical aspects.
PIGMENTS FROM THE BOTTOM DEPOSITS OF AN ENGLISH LAKE
Authors: FOGG G. E. , BELCHER J. H.
Published: May 2006

Summary

Acetone‐soluble pigments in the sediments of Esthwaite Water, English Lake District, have been separated and characterized chromatographically and spectrophotometrically. Chlorophyll degradation products similar to those described from North American lakes have been found to predominate but α‐ and β‐carotene, lutein, and two unidentified epiphasic‡carotenoids were also present. In an attempt to relate the amounts of these pigments at different depths to the ecological history of the lake and its catchment area, total amounts of chlorophyll degradation products, of epiphasic carotenoids (mainly β‐carotene), and of hypophasic‡carotenoid (lutein), have been determined in samples taken at 10 cm intervals from a core reaching down into the glacial clays. The amounts of each of these three types of pigment were found to show a general correlation with the amounts of organic matter at different depths in the deposits and certain fluctuations appear to be related to ecological changes in the past. The ratio of chlorophyll degradation products to epiphasic carotenoids has been found to remain nearly constant down to 100 cm, indicating that no appreciable decomposition of these pigments has occurred since the sediments were laid down, and below this to fluctuate in a rather regular manner with peaks at about 53 cm intervals (a statistical examination of these fluctuations is included as an appendix). The ratio of chlorophyll degradation products to hypophasic carotenoid has been found to vary in a similar manner except for a general trend indicating the slow decomposition of lutein. These results suggest the occurrence of regular cyclic ecological changes from the Boreal period onwards which were interrupted at about A. D. 1000 by forest clearance.
BALLISTICS IN CERTAIN ASCOMYCETES
Authors: INGOLD C. T.
Published: May 2006

Summary

Horizontal spore discharge has been studied in the genera Daldinia, Sordaria, Pleurage and Ascobolus. The average distance of discharge for the full spore‐complement of the ascus increases with the size of the projectile. In Pleurage taenioides a consideration of the form of the ascus jet, as caught on a rapidly rotating disk, suggests that as the four spores are shot from the ascus the vigour of discharge tends to fall with the escape of successive spores.
PHYSIOLOGICAL STUDIES OF GERMINATION IN THE GENUS AVENA
Authors: DRENNAN DONALD S. H. , BERRIE ALEX M. M.
Published: May 2006

Summary

The development of amylase activity has been studied in dormant and germinating grains of Avena sativa, A. fatua and A. ludoviciana. Little activity was present in dry grains but activity increased considerably during the first few days in germination conditions in non‐dormant grains. Dormant grains showed no increased activity during considerable periods in the imbibed condition.

α‐Amylase development was responsible for the bulk of the increased amylase activity but β‐amylase development also occurred. The increased amylase activity was first noted in the endosperm and did not take place until after the resumption of growth in the embryo in all three species. Parts of grains of A. sativa cultured independently showed no capacity to develop increased amylase activity in a manner similar to that of the whole grain.

It is suggested that the development of amylase activity is brought about in the endosperm in response to a stimulus from the growing embryo, and that development of increased amylase activity is thus a post‐germination change. The association of this aspect of metabolism with the dormant condition in the wild oats must therefore be dismissed as a potential cause of dormancy.
PLASTID ULTRASTRUCTURE IN THE BARREL CACTUS, ECHINOCACTUS ACANTHODES
Authors: THOMSON WILLIAM W. , PLATT KATHRYN
Published: May 2006

The unique feature of the plastids in the stem of the barrel cactus is the presence of exceedingly large and often numerous plastoglobuli. In the outer green tissue the chloroplasts are similar in ultrastructure to those of other angiosperms except for the presence of numerous plastoglobuli of various sizes and the absence of starch. In the inner, light‐green transition zone adjacent to the cortical tissue, the chloroplasts have large and small plastoglobuli but also contain some starch. The dominant features of the plastids in the cortical and pith tissues are plastoglobuli, accumulations of phytoferritin and the reduction or absence of grana and starch. These observations suggest that the primary storage product in cactus plastids are lipids which accumulate into plastoglobuli. In the transition zone the plastoglobuli are fewer in number than in the outer green tissue and the large plastoglobuli contain regions of electron translucency both of which are indications that the plastoglobuli are being degraded. A possible relationship between the plastoglobuli and starch through gluconeaogenesis is suggested by the tight association of microbodies with the chloroplasts in this tissue. The plastids in the light‐green transition zone, cortical and pith tissue are irregular in shape which is interpreted to indicate that the form of the plastids in these tissues is dynamic.
MODERATE‐TERM WATER STRESSES AND ASSOCIATED CHANGES IN SOME PHOTOSYNTHETIC PARAMETERS IN COTTON
Authors: JONES HAMLYN G.
Published: May 2006

Cotton plants (Gossypium hirsutum L., var Deltapine smoothleaf) were subjected to 1‐ or 2‐week periods of mild water stress using an osmotic soil cell. The treatments were severe enough to affect seriously several photosynthetic parameters, while good night‐time recovery of plant water‐potential minimized effects on development and leaf expansion.

Most measurements were made soon after rewatering, owing to very high stomatal resistances in the stressed plants. The stressed plants had lower rates of potential photosynthesis and lower rates of actual photosynthesis (at normal ambient CO2 concentrations) than the controls. Both stomatal and intracellular resistances and the corresponding ‘photosynthetic limitations’ were greater in the stressed plants than the controls. Most of these parameters showed fairly complete recovery 24 hours after rewatering. Parallel changes were observed in the activities of carbonic anhydrase, ribulosediphosphate carboxylase and 14C fixation by leaf slices, all of which were lower in the stressed plants.

Although activities of all the processes studied showed parallel changes, there was evidence that the major factor causing reduced photosynthesis in the stressed plants was stomatal closure. There was some evidence that the photosynthetic system adjusted itself to water stress over the periods studied.
THE PATHWAY OF TRANSPORT OF APPLIED INDOLYL‐ACETIC ACID THROUGH INTERNODE SEGMENTS
Authors: WANGERMANN ELISABETH
Published: May 2006

Summary

Helianthus internode segments were fitted with apical donor blocks containing [14C]IAA and [3H]sucrose, and plain agar basal receiver blocks. After transport, donors, tissue and receivers were oxidized in an ‘Oxymat’ and 14C and 3H counted separately. Ageing the segments before transport, or pretreatment with TIBA, greatly reduced the amount of 14C in the receivers, but had no effect on the 3H count.

Profiles of 14C were determined after transport of [14 C]IAA through similar segments ringed to various depths, or with the pith interrupted. Interruption of the vascular bundles, but not of the pith, caused accumulation of I4C above the cut in segments transporting IAA basipetally; no accumulation was caused by ringing segments transporting IAA acropetally.

It is concluded that active polar transport of IAA takes place in or near the phloem, but by a different mechanism from the one involved in sucrose transport through the phloem of intact plants.
THE BIOLOGY OF MYCORRHIZA IN THE ERICACEAE
Authors: STRIBLEY D. P. , READ D. J.
Published: May 2006

Summary

The major soluble carbohydrates of mycorrhizal and non‐mycorrhizal roots of the cultivated cranberry, Vaccinium macrocarpon Ait., have been identified and quantitatively analysed. Mycorrhizal roots contained two sugars, mannitol and trehalose, not found in uninfected roots. As these sugars are abundant in extracts of endophyte mycelium grown in liquid culture, they appear to be of fungal origin. Analysis of neutral sugars derived by acid hydrolysis of insoluble residues showed an accumulation of a mannose‐containing polymer in mycorrhizal roots. Mannose was a principal component of insoluble polymers in the endophyte.

All soluble carbohydrates in the root, including mannitol and trehalose, became labelled after feeding 14CO2 to the shoots. Sucrose was the most strongly labelled sugar in both types of root. Mannose present in hydrolysates of mycorrhizal roots was more heavily labelled than that derived from uninfected roots but most 14C in insoluble fractions was found in glucose polymers.

The hypothesis that the endophyte derives a supply of carbohydrate from its host plant is discussed.
ON HORMONES AND WEEPING: ASYMMETRIC HORMONE DISTRIBUTION AND THE PENDULOUS GROWTH HABIT OF THE WEEPING MULBERRY, MORUS ALBA VAR. PENDULA
Authors: RECHES S. , LESHEM Y. , WURZBURGER J.
Published: May 2006

Summary

The possibility that asymmetric hormone distribution causes downward bending of weeping mulberry (Morus alba var. pendula) twigs was investigated. By extraction, bioassay and gas chromatography it was shown that while upper and lower twig sections had no differences in auxin activity, the two sides differed considerably in content of GA and ABA. The lower side contained high levels of endogenous GA while the upper side had higher concentrations of ABA. The significance of these results and their possible role in the weeping habit of tree growth are discussed. It is suggested that the high GA levels coupled to low ABA content induce greater lignification on the lower side of the twig and that this tissue is less sensitive to auxin and has a lower growth response than the upper side of the twig thus causing a downward inclination of growth.
CARBOHYDRATE COMPOSITION AND METABOLISM OF SENECIO SQUALIDUS L. LEAVES INFECTED WITH ALBUGO TRAGOPOGONIS (PERS.) S. F. GRAY
Authors: LONG D. E. , COOKE R. C.
Published: May 2006

Summary

The soluble and insoluble carbohydrates of healthy and Albugo‐infected leaves of Senecio squalidus were determined qualitatively. Quantitative analyses were made of the soluble carbohydrates. Trehalose was synthesized within pustules by the fungus but no acyclic polyols were found. Accumulation of hexoses around pustules together with increased hydrolysis of exogenous sucrose by pustular material indicated increased invertase activity within infected tissues. It is suggested that host‐fungus movement of carbohydrates in Albugo is maintained by hydrolysis of host sucrose and uptake of hexoses, followed by accumulation of trehalose within the mycelium and spores.
THE BIOLOGY OF DAUCIFORM ROOTS IN THE SEDGE CYATHOCHAETE AVENACEA
Authors: LAMONT BYRON
Published: May 2006

Summary

Small, carrot‐shaped roots produced by Cyathochaete avenacea (Cyperaceae) were investigated. Quantitative data are given on their comparative morphology, anatomy and soil‐plant relationships. While factors controlling their formation appear to have much in common with those controlling proteoid root formation, their origin and structure are quite different. The cyperaceous roots become endomycorrhizal late in their development. These root structures are essentially distinct from any described in other families, and the term ‘dauciform’ is proposed to distinguish them.
THE LOCATION OF REFUGIA OF CORYLUS AVELLANA L. DURING THE WEICHSELIAN GLACIATION
Authors: DEACON JOY
Published: May 2006

Summary

A survey was made of all existing radiocarbon dates relating to the Corylus rise in Europe in order to find the possible areas of refugia of Corylus during the Weichselian glaciation. Using the radiocarbon dates an isochron map was drawn which indicated areas of refugia off the west coast of the British Isles, south‐west Scandinavia and in south‐western Europe. The possible routes of migration of Corylus are indicated on this. On the basis of the radiocarbon dates the rates of migration of Corylus along the possible routes have been calculated and show that migration from northern refugia was faster than that from southern refugia.

The climatic and edaphic conditions in the suggested refugia during the Weichselian glaciation and their importance in relation to the survival of Corylus are discussed. The number of radiocarbon dates is inadequate for definite conclusions to be drawn on the location of refugia and so the need for an extensive programme of radiocarbon dating of important pollen strati‐graphic events in Europe is stressed.
IN VITRO BUD FORMATION IN STEM SEGMENTS OF AILANTHUS ALTiISSIMA
Authors: CARUSO JOHN L.
Published: May 2006

Excised internodal segments of Ailanthus altissima were grown aseptically on a defined nutrient medium which lacked added growth regulators. Vascular cambium, phloem or cortex, depending upon which of these tissues is exposed, undergoes tangential cell divisions and produces new tissue on top of the explant. Buds appear in surface layers of the newly formed tissue. Seasonal controls of this process are evident from the greater amount of regeneration in samples collected in spring (March‐May).
THE PALAEOHISTORY OF THE GREY ALDER (ALNUS INCANA (L.) MOENCH.) AND BLACK ALDER (A. GLUTINOSA (L.) GAERTN.) IN FENNOSCANDIA
Authors: TALLANTIRE P. A.
Published: May 2006

The available 14C‐dated and broadly context‐dated pollen and macrofossil data for the immigration and spread of the two species of alder within Fennoscandia and certain adjacent countries is presented. The phases of immigration and regional spread take place during certain periods of time (e.g. 6500, 6000, 5000 and 4500 14C years B.C.) and over certain restricted geographical areas. The latter yield a picture of climatic regionalism, with limits akin to that of the present day. Along its present, diffuse northern boundary Alnus glutinosa, on the evidence from Tran‐delag in Norway, appears to have become established only in a late phase of the broad climatic optimum, after 2000 B.C., and to have lost ground again after c. 700 B.C., though the course of later events is confused by human activity. A tabulation of the postulated ecological requirements of the two species of alder at various stages of their life histories is attempted. Details of the sites mapped are included in an appendix.
VEGETATIONAL HISTORY OF THE IPSWICHIAN/EEMIAN INTERGLACIAL IN BRITAIN AND CONTINENTAL EUROPE
Authors: PHILLIPS LINDA
Published: May 2006

The vegetational history of the Ipswichian (last) Interglacial in Britain is discussed in terms of the behaviour of the various trees and shrubs, the marked opening of the vegetation in the latter part of the interglacial, and climatic indications given by the plant assemblages. The vegetational history of the correlative Eemian Interglacial of the European mainland is surveyed geographically, with particular reference to the differences between the Continent and Britain, and to the variations in the flora and vegetational history between north‐west Europe, Poland and southern Europe north of the Alps. Special attention is given to the behaviour of Tilia, Taxus, Acer, Picea and Abies.
SUPEROXIDE DISMUTASE, CATALASE AND GLUTATHIONE PEROXIDASE: SOLUTIONS TO THE PROBLEMS OF LIVING WITH OXYGEN
Authors: Halliwell B.
Published: May 2006

Recent research suggests that H2O2 is a normal metabolite in both plants and animals and is not particularly cytotoxic. The impact of H2O2 on cell metabolism is discussed with particular reference to photorespiration. Catalase may function by preventing the formation of excessive concentrations of H2O2 and by using H2O2 in the peroxidatic oxidation of compounds such as methanol and formic acid. Radicals (such as OH and O2‐) and ‘excited’ oxygen are far more damaging to living organisms. The formation of these radicals in biological systems is described. Superoxide dismutase plays a key role in protection against such radicals, but glutathione peroxidase is also involved.