bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantitative Assessment of Serum NV-F Virus DNA Concentrations in Samples from Patients Coinfected with Hepatitis B or C Virus
Authors: Hsu Chao-Wei , Cheng Ju-Chien , Yeh Chau-Ting
Published: September 2006

A novel hepatotropic virus, named NV-F virus, was recently identified. The clinical information for this virus is still scarce. Using PCR assay, NV-F viral DNA (NV-F-DNA) was detected in 12 of 50 (24%) hepatitis C virus (HCV)-infected patients (HCV-coinfected [HCVCI] group), 34 of 250 (13.6%) hepatitis B virus (HBV)-infected patients (HBV-coinfected [HBVCI] group), and 28 of 100 (28%) non-A-to-E (NAE) hepatitis patients. Basic clinical parameters were not significantly different among the three groups. By use of a PCR-based quantitative assay, the NV-F-DNA concentration was found to be above the detection limit (1.2 × 10
5
copies/ml) in 12/12 (100%) HCVCI patients, 14/34 (41.2%) HBVCI patients, and 4/28 (14.3%) NAE patients. The median serum NV-F-DNA concentration was 9.3 × 10
5
copies/ml in HCVCI patients, but it was below the detection limit in HBVCI and NAE patients (
P
values were 0.0045 and 0.0001, respectively). Stepwise multiple regression analysis identified the presence of anti-HCV as an independent factor for NV-F-DNA concentrations (β = 6.2 × 10
9
;
P
= 0.0245). In HBVCI patients, the NV-F-DNA concentration was inversely correlated with the HBV DNA concentration. The median NV-F-DNA concentration was below the detection limit in patients with HBV DNA concentrations above 1.4 × 10
5
copies/ml, but it was 1.58 × 10
6
copies/ml in patients with HBV DNA concentrations below 1.4 × 10
5
copies/ml (
P
= 0.030). In conclusion, NV-F-DNA concentrations were higher in HCVCI patients. A reciprocal relationship was found between NV-F-DNA and HBV DNA concentrations in HBVCI patients, indicating the presence of viral interference between these two DNA viruses.
Ventilator-Associated Pneumonia Caused by
Dolosigranulum pigrum
Authors: Hoedemaekers A. , Schülin T. , Tonk B. , Melchers W. J. G. , Sturm P. D. J.
Published: September 2006

Dolosigranulum pigrum
is an unusual gram-positive catalase-negative coccus. It was isolated, only after prolonged incubation, from bronchial secretions from a patient with ventilator-associated pneumonia. The patient responded well to antimicrobial therapy. Identification was done by 16S rRNA DNA sequence analysis, but it can be done with relatively simple phenotypic tests.
Comparison of Tests To Detect Oxacillin Resistance in
Staphylococcus intermedius
,
Staphylococcus schleiferi
, and
Staphylococcus aureus
Isolates from Canine Hosts
Authors: Bemis David A. , Jones Rebekah D. , Hiatt Lauren E. , Ofori Edward D. , Rohrbach Barton W. , Frank Linda A. , Kania Stephen A.
Published: September 2006

Multiple tests were compared to the reference standard PBP2a latex agglutination test for detection of
mecA
-mediated oxacillin resistance in canine staphylococci. Cefoxitin disk diffusion, using breakpoints for human isolates of coagulase-negative
Staphylococcus
spp., had low sensitivity for detection of oxacillin resistance in members of the
Staphylococcus intermedius
group.
The Key Role of Pulsed-Field Gel Electrophoresis in Investigation of a Large Multiserotype and Multistate Food-Borne Outbreak ofSalmonellaInfections Centered in Pennsylvania
Authors: Sandt Carol H. , Krouse Donna A. , Cook Charles R. , Hackman Amy L. , Chmielecki Wayne A. , Warren Nancy G.
Published: September 2006

Five different serotypes ofSalmonella entericawere implicated in a large outbreak linked to fresh Roma tomatoes served at gas station deli counters in Pennsylvania and nearby states during July 2004:S. entericaserotypes Javiana, Anatum, Thompson, Typhimurium, and Muenchen. One of these serotypes, Anatum, was isolated from both tomatoes and patients. Pulsed-field gel electrophoresis (PFGE) played a key role in identifying the outbreak-associated isolates and distinguishing them from unrelated sporadic isolates. It also demonstrated that the genetic fingerprints of serotype Anatum isolates derived from patients were indistinguishable from those derived from tomatoes. Rapid communication of PFGE fingerprints with other public health laboratories through the Centers for Disease Control and Prevention's PulseNet USA national molecular surveillance network for bacterial food-borne pathogens facilitated the tracking of this outbreak in other states. The work described in this report emphasizes the laboratory's role in core public health functions and services, thereby providing a highly visible example of public health in action.
Mycobacterium tuberculosis
Complex and Mycobacterial Heat Shock Proteins in Lymph Node Tissue from Patients with Pulmonary Sarcoidosis
Authors: Dubaniewicz Anna , Dubaniewicz-Wybieralska Mirosława , Sternau Adam , Zwolska Zofia , Iżycka-Świeszewska Ewa , Augustynowicz-Kopeć Ewa , Skokowski Jarosław , Singh Mahavir , Zimnoch Lech
Published: September 2006

We demonstrated that not whole
Mycobacterium tuberculosis
but its particular antigens, hsp70

Mtb

, hsp65

Mtb

, and hsp16

Mtb

, are present in lymph node tissues of patients with sarcoidosis (SA). hsp16

Mtb

occurs in the early stage of SA, whereas hsp70

Mtb

occurs in stage II of SA. hsp65

Mtb

is highly expressed in the capillary vessels in lymph node tissues in patients with SA.
Quinupristin-Dalfopristin Resistance inEnterococcus faeciumIsolates from Humans, Farm Animals, and Grocery Store Meat in the United States
Authors: Donabedian S. M. , Perri M. B. , Vager D. , Hershberger E. , Malani P. , Simjee S. , Chow J. , Vergis E. N. , Muder R. R. , Gay K. , Angulo F. J. , Bartlett P. , Zervos M. J.
Published: September 2006

Three hundred sixty-one quinupristin-dalfopristin (Q-D)-resistantEnterococcus faecium(QDREF) isolates were isolated from humans, turkeys, chickens, swine, dairy and beef cattle from farms, chicken carcasses, and ground pork from grocery stores in the United States from 1995 to 2003. These isolates were evaluated by pulsed-field gel electrophoresis (PFGE) to determine possible commonality between QDREF isolates from human and animal sources. PCR was performed to detect the streptogramin resistance genesvatD,vatE, andvgbAand the macrolide resistance geneermBto determine the genetic mechanism of resistance in these isolates. QDREF from humans did not have PFGE patterns similar to those from animal sources.vatEwas found in 35%, 26%, and 2% of QDREF isolates from turkeys, chickens, and humans, respectively, and was not found in QDREF isolates from other sources.ermBwas commonly found in QDREF isolates from all sources. Known streptogramin resistance genes were absent in the majority of isolates, suggesting the presence of other, as-yet-undetermined, mechanisms of Q-D resistance.
Temperature Gradient Gel Electrophoresis of Fecal 16S rRNA Reveals Active
Escherichia coli
in the Microbiota of Patients with Ulcerative Colitis
Authors: Sokol H. , Lepage P. , Seksik P. , Doré J. , Marteau P.
Published: September 2006

Previous studies of the endogenous microbiota in patients with ulcerative colitis (UC) have not taken bacterial activity into account, yet bacteria with high transcriptional activity might have a more important pathophysiological role than inactive bacteria. We therefore analyzed the biodiversity of active bacteria in the fecal microbiota of UC patients, in comparison with that of healthy subjects. Feces were collected from nine patients with active UC and from nine healthy controls. Total DNA and RNA were extracted, and 16S ribosomal DNA and RNA were amplified by PCR and reverse transcription-PCR, respectively. Amplification products were compared by means of temporal temperature gradient gel electrophoresis (TTGE). Bands of interest were excised, sequenced, and identified by comparison with the GenBank database (NCBI). The dominant-species diversity based on RNA-derived TTGE profiles was significantly lower for UC patients than for healthy controls (
P
= 0.01). The mean similarity index between the “present” and “active” microbiota was 74% ± 18% for UC patients. Comparison of the individual “active” microbiota identified a band that was present for eight UC patients and only two controls (89% versus 22%;
P
= 0.008). The band was sequenced for 6 patients and always corresponded to
Escherichia coli
. The biodiversity of active bacteria in the dominant fecal microbiota of patients with UC is lower than that of healthy subjects.
E. coli
is more represented in the active microbiota of UC patients. The possible pathophysiological role of this difference remains to be determined.
Enhanced Patient Serum Immunoreactivity to Recombinant
Mycobacterium tuberculosis
CFP32 Produced in the Yeast
Pichia pastoris
Compared to
Escherichia coli
and Its Potential for Serodiagnosis of Tuberculosis
Authors: Benabdesselem Chaouki , Fathallah Dahmani M. , Huard Richard C. , Zhu Hongxia , Jarboui Mohamed Ali , Dellagi Koussay , Ho John L. , Barbouche Ridha M.
Published: September 2006

CFP32 is a
Mycobacterium tuberculosis
complex-restricted secreted protein that was previously reported to be present in a majority of sputum samples from patients with active tuberculosis (TB) and to stimulate serum antibody production. CFP32 (originally annotated as Rv0577 and also known as TB27.3) was therefore considered a good candidate target antigen for the rapid serodiagnosis of TB. However, the maximal sensitivity of CFP32 serorecognition may have been limited in earlier studies because recombinant CFP32 (rCFP32) produced in
Escherichia
c
oli
was used as the test antibody-capture antigen, a potential shortcoming stemming from differences in bacterial protein posttranslational modifications. To further investigate the serodiagnostic potential of rCFP32 synthesized in different heterologous hosts, we expressed rCFP32 in the yeast
Pichia pastoris
. Compared to
E. coli
rCFP32, yeast rCFP32 showed a higher capacity to capture polyclonal antisera in Western blot studies. Likewise, yeast rCFP32 was significantly better recognized by the sera from TB patients and healthy
Mycobacterium bovis
bacillus Calmette-Guérin (BCG)-vaccinated individuals, by enzyme-linked immunosorbent assay (ELISA), than
E. coli
rCFP32. In subsequent testing, the yeast rCFP32-based antibody-capture ELISA had a sensitivity of 85% and a specificity of 98% for the discrimination of active TB cases (
n
= 40) from BCG vaccinees (
n
= 39). The sensitivity was surprisingly high for a single-antigen TB serodiagnostic test compared to tests using
E. coli
-expressed antigens. Overall, the
trans
-production of rCFP32 in
P. pastoris
significantly improved the serologic detection of CFP32-specific antibodies in patient sera, thereby offering a new, possibly better, modality for producing antigens of diagnostic potential for use in the development of immunoassays for both TB and other infectious diseases.
Hip Prosthesis Infection Due to
Mycobacterium wolinskyi
Authors: Pulcini Céline , Vandenbussche Eric , Podglajen Isabelle , Sougakoff Wladimir , Truffot-Pernot Chantal , Buu-Hoï Annie , Varon Emmanuelle , Mainardi Jean-Luc
Published: September 2006

Mycobacterium wolinskyi
, first described in 1999, is a rapidly growing mycobacterium related to the
Mycobacterium smegmatis
group. Only eight cases of infection due to this microorganism have been reported, including three cases of bone infection. Here, we present the first case of a joint prosthesis infection cured with the combination of surgery and prolonged antibiotic therapy. The microorganism was identified by biochemical tests and 16S rRNA and Hsp65 gene sequence analysis.
Post-stroke seizure and post-stroke epilepsy
Authors: Myint P K , Staufenberg E F A , Sabanathan K
Published: September 2006

Post-stroke seizure and post-stroke epilepsy are common causes of hospital admissions, either as a presenting feature or as a complication after a stroke. They require appropriate management and support in long term. With an increasingly ageing population, and age itself being an independent risk factor for stroke, the incidence and prevalence of post-stroke seizure and post-stroke epilepsy is likely to increase. This article examines aetiology, clinical presentation, and presents a management outline of these conditions with particular focus on adults. The aim of this review article is to provide the clinicians with background information and recommendations.
Cyclooxygenase-2 plays an essential part in cardioprotection of delayed phase of recombinant human erythropoietin preconditioning in rats
Authors: Liu X , Zhou Z , Feng X , Jia Z , Jin Y , Xu J
Published: September 2006

Aims

To study the cardioprotection of recombinant human erythropoietin (rhEPO) preconditioning (EPC) and to investigate the role and possible mechanism of cyclooxygenase (COX)-2 in the delayed phase of EPC.

Methods

In phase 1, myocardial ischaemia reperfusion (I-R) rat model was established by 30 minutes ligation of left descending coronary and three hours of reperfusion. Rats were given 0.9% saline solution or rhEPO 24 hours before I-R protocol. COX-2 selective inhibitor celecoxib was given for further investigation of the cardioprotection of EPC. At the end of I-R protocol, infarct sizes were measured and ultrastructural organisations were studied. In phase 2, myocardial COX-2 mRNA expressions and prostaglandins (PGs) contents were studied in different groups after euthanasia.

Results

It was found that EPC could elicit potent cardioprotection against I-R injury, shown by reduction of infarct size and improvement of ultrastructural organisation; whereas administration of celecoxib resulted in complete loss of this protection. EPC resulted in robust increase in COX-2 mRNA and PGs levels that were also abrogated by celecoxib.

Conclusions

COX-2 plays an essential part in cardioprotection of the delayed phase of EPC in rats, which might be related to actions of PGE2 or PGI2, or both.
Pulmonary leptospirosis: an excellent response to bolus methylprednisolone
Authors: Shenoy V V , Nagar V S , Chowdhury A A , Bhalgat P S , Juvale N I
Published: September 2006

Background

This case series analyses the beneficial effect of methylprednisolone in pulmonary leptospirosis, which usually has an aggressive course and grave outcome.

Methods

30 patients of pulmonary leptospirosis were evaluated. The initial 13 patients did not receive corticosteroids while the remaining 17 all received bolus methylprednisolone one gram intravenously for three days followed by oral prednisolone 1 mg/kg for seven days, on the basis of occasional case reports of benefit in pulmonary leptospirosis. APACHE III and lung injury scores of similar severity were considered while comparing outcomes in those who received methylprednisolone with those who did not.

Results

Dyspnoea and haemoptysis were the commonest symptoms in those with pulmonary manifestations. Overall mortality was 18% (3 of 17) in patients who received methylprednisolone, as compared with 62% (8 of 13 patients) in those who did not (p<0.02). In patients with established acute lung injury (ALI score >2.5), five of eight patients survived in the subgroup with corticosteroids (37% mortality) while only one of nine patients survived in the group that did not receive corticosteroids (89% mortality). Corticosteroids affected outcome only if given within the first 12 hours after the onset of pulmonary manifestations. Mortality seemed to correlate with the APACHE scores, and number of quadrants affected on chest radiographs, more than with blood gas pressures.

Conclusions

Corticosteroids reduce mortality and change outcome significantly when used early in the management of pulmonary leptospirosis.
Comparison of transthoracic echocardiography with harmonic imaging with transoesophageal echocardiography for the diagnosis of patent foramen ovale
Authors: Trevelyan J , Steeds R P
Published: September 2006

The optimal diagnostic method for patent foramen ovale is currently unclear. This study compared bubble contrast second harmonic transthoracic (TTE) and transoesophageal echocardiography (TOE) on 87 consecutive patients referred for TOE for all indications. A right left shunt was diagnosed in 34 cases (39%), with TTE positive in 26 cases (sensitivity 76.5%), TOE positive in 27 cases (sensitivity 79.4%). Pitfalls of TTE included quality of echo and left sided valve lesions, and for TOE the ability to perform an adequate Valsalva manoeuvre. In conclusion, both tests have similar sensitivity and should be viewed as complementary modalities.
Anti-inflammatory action of diltiazem in patients with unstable angina
Authors: Dubey L , Hesong Z
Published: September 2006

Background and Aims

Plasma concentrations of anti-inflammatory cytokine interleukin 10 (IL10) have been shown to be decreased in patients with unstable angina (UA) suggesting that reduced concentrations of IL10 may favour plaque instability and the development of acute coronary syndromes. Diltiazem has been shown to exert beneficial effects in patients with acute coronary syndrome. However, the potential influence of diltiazem on the anti-inflammatory cytokine IL10 in patients with UA has not been investigated. This study was designed to find out the effects of diltiazem on IL10 in UA patients.

Methods and Results

Thirty patients with UA were divided into two groups: group R and group D (n = 15). Group R was given routine pharmacotherapy for UA, and group D was given routine pharmacotherapy plus diltiazem. Plasma concentrations of IL10 in these groups were measured before the start of the treatment and 28 days after treatment. Plasma concentrations of IL10 in 15 normal subjects (group N) were also measured. Patients with UA had decreased concentrations of IL10 compared with normal group. Four weeks after treatment, plasma concentrations of IL10 significantly increased in group D compared with that before treatment, but the increase in IL10 values in group R was not significant.

Conclusions

These findings showed that concentrations of anti-inflammatory IL10 are considerably decreased in UA patients and diltiazem treatment leads to a significant increase in IL10 concentrations.
Perceptions of medical school graduates and students regarding their academic preparation to teach
Authors: Henry B W , Haworth J G , Hering P
Published: September 2006

Purpose

How medical students learn and develop the characteristics associated with good teaching in medicine is not well known. Information about this process can improve the academic preparation of medical students for teaching responsibilities. The purpose of this study was to determine how different experiences contributed to the knowledge, skills, and attitudes of medical school graduates and students regarding medical teaching.

Methods

A questionnaire was developed, addressing reliability and validity considerations, and given to first year residents and third year medical students (taught by those residents). Completed questionnaires were collected from 76 residents and 110 students (81% of the sample group). Item responses were analysed using descriptive and inferential statistics.

Results

Most residents (n = 54; 71%) positively viewed opportunities they had to practice teaching when they were seniors. Residents rated three activities for learning to teach highest: (1) observing teachers as they teach; (2) reviewing the material to be taught; and (3) directly teaching students; representing both individual and participatory ways of learning. Residents' self ratings of teaching behaviours improved over time and this self assessment by the residents was validated by the students' responses. Comparison between residents' self ratings and students' views of typical resident teaching behaviours showed agreement on levels of competence, confidence, and motivation. The students rated characteristics of enthusiasm, organisation, and fulfilment lower (p<0.002) than residents rated themselves.

Conclusions

The residents and students in this study viewed academic preparation for teaching responsibilities positively and showed agreement on characteristics of good teaching that may be helpful indicators in the process of developing medical teachers.
Twenty four hour ambulatory blood pressure monitoring: a new tool for determining cardiovascular prognosis
Authors: Madin K , Iqbal P
Published: September 2006

Twenty four hour ambulatory blood pressure monitoring (24-H ABPM) plays an important part in the management of subjects with suspected and confirmed disorders of blood pressure regulation. This article reviews the prognostic significance of various aspects of the 24-H ABPM and describes the authors experience in Chesterfield. Over the course of 12 month period from 1 August 2002, 1264 subjects had 24-ABPM. A total of 1187 (93.91%) subjects were included in this study, with mean age of 59.30 years and male:female ratio was 46%: 54 %. Fifty two (4.38%) of the subjects had all of the seven features associated with an adverse prognosis. Only 82 (6.90%) subjects had none of the seven adverse prognostic features with the remainder having one or more adverse prognostic features.
Reversible acute adrenal insufficiency caused by fluconazole in a critically ill patient
Authors: Santhana Krishnan S G , Cobbs R K
Published: September 2006

A 38 year old man with history of obstructive sleep apnea and polycythaemia presented with hypercapnic respiratory failure that required intubation. He developed fever with infiltrates on chest radiography that required empiric antifungal therapy with fluconazole along with broad spectrum antibiotics. He developed acute adrenal insufficiency that recovered after fluconazole was stopped. It is believed that this complication of adrenal suppression attributable to fluconazole is underrecognised and it may be prudent to monitor all critically ill patients who are given fluconazole for this complication.
Environmental influences on aquatic plants in freshwater ecosystems
Authors: Lacoul Paresh , Freedman Bill
Published: September 2006

Aquatic plants are important components of many freshwater ecosystems. In this review we examine natural and anthropogenic influences on the distribution and abundance of aquatic plants, and develop a conceptual model of those diverse interactions. Species of aquatic plants vary greatly in their anatomy, physiology, life-history traits, and ability to tolerate inorganic and biological stressors. Key examples of inorganic stressors are extreme regimes of flow velocity, irradiance, salinity, ice cover, temperature, nutrients, and pollutants. Stressors associated with competition, herbivory, and disease may also limit the ability of species to utilize otherwise suitable habitats. Some aquatic plants have a cosmopolitan distribution and display high levels of polymorphism and phenotypic plasticity in response to variations of environmental factors; these qualities allow them to occur over a wide range of conditions. Other species, however, have narrower tolerances and are potentially useful indicators of environmental conditions, in terms of either their presence or relative abundance within communities. In this review, we examine key environmental influences affecting aquatic plants, and their potential use as indicators at local, watershed, and regional scales.Key words: aquatic plants (aquatic macrophytes), environmental factors, environmental indicators, environmental stressors.
The Northern Fulmar (Fulmarus glacialis) in Arctic Canada: ecology, threats, and what it tells us about marine environmental conditions
Authors: Mallory Mark L
Published: September 2006

The northern fulmar Fulmarus glacialis is a ubiquitous seabird found across the North Atlantic Ocean and into the Canadian Arctic. However, we know little of its ecology in the Arctic, which is unfortunate, because it possesses many traits that make it an excellent biomonitor of the condition of Arctic marine environments. Presently, Arctic fulmars face threats from harvest, bycatch in fisheries, and fouling in oil spills while the birds are in their winter range (the North Atlantic). However, during breeding, migration, and overwintering, they may also experience stress from ecotourism, contaminants, particulate garbage, and climate change. In this paper I review the effects of all of these threats on fulmars and I describe how the ecology of these birds makes them particularly suitable for tracking contaminants, garbage, and the effects of climate change in the Arctic marine ecosystem. I also highlight our key existing knowledge gaps on this species and how additional research will strengthen the utility of fulmars as biomonitors. Key words: northern fulmar, Fulmarus glacialis, Arctic, contaminants, climate change, pollution.
Comparison of the development of stem galls induced byAulacidea hieracii(Hymenoptera: Cynipidae) on hawkweed and byDiplolepis spinosa(Hymenoptera: Cynipidae) on rose
Authors: Sliva Monica D. , Shorthouse Joseph D.
Published: September 2006

Plant galls induced by two distantly related species of cynipid wasps, Aulacidea hieracii Bouché, which belongs to a basal lineage and induces galls on Hieracium umbellatum L., and Diplolepis spinosa (Ashmead), which belongs to a derived group and induces galls on Rosa blanda Ait. and Rosa rugosa Thunb., were compared. As gall characters are determined by the wasp rather than the host plant, we hypothesized that information on gall development would contribute to our understanding of the evolution of the cynipid complex. Galls induced by both species are spherical and multichambered and arise on stems. All stages of gall development were examined including host plant response to oviposition and the eggs, gall induction, reaction of the plant to larval feeding, and the formation of nutritive cells, vascular tissues, and sclerenchyma within the gall during growth and maturation. Galls of A. hieracii develop in a manner similar to galls inhabited by inquiline cynipids, a basal lineage to which they are closely related. Aulacidea hieracii lay eggs in a sticky cluster, the eggs cause proliferation of nearby stem tissues, and freshly hatched larvae crawl to sites where each induces a separate chamber. Galls of D. spinosa are induced from eggs deposited in slits between the base of leaf primordia near the tips of leaf buds with one end of the egg touching the procambium. Freshly hatched larvae enter a cavity that forms beneath each egg. Galls of A. hieracii exhibit anatomical and developmental features that are less complex and intricate than are the galls of D. spinosa. The term “asterids” is proposed for cynipid galls that are developmentally and anatomically simple and develop on herbaceous plants and the term “rosids” for cynipid galls that are developmentally and anatomically complex and develop on woody plants such as roses and oaks.
Basidiomycetous endophytes in jungermannialean (leafy) liverworts have novel cytology and species-specific host ranges: a cytological and experimental study
Authors: Duckett Jeffrey G. , Russell Julia , Ligrone Roberto
Published: September 2006

This article reviews published data on the likely occurrence of basidiomycetous endophytes in jungermannialean (leafy) liverworts and presents a new overview based on observations on freshly collected specimens supplemented with confirmation, by transmission electron microscopy, of dolipore septa in representative taxa. These associations are widespread in the Lophoziaceae and Arnelliaceae and sporadic in the Jungermanniaceae, Scapaniaceae, and Geocalycaceae. They are almost exclusively confined to taxa growing on well-drained, humus-rich substrata and are absent from epiphytes and species from bare rocks and waterlogged habitats. Cross-infection experiments between axenically cultured liverworts ( Lophozia , Nardia , Diplophyllum , Southbya , and Aneura in the Metzgeriales) and their mycobionts revealed the associations to be host specific, in striking contrast with the wide host ranges previously recorded for rhizoidal ascomycetes in the Cephaloziaceae and other families. More vigorous growth of resynthesized basidiomycete associations compared with their axenic counterparts is indicative of nutritional benefits to the liverworts. The fungi enter their hosts via the tips of the rhizoids and develop distinctive distributions within the liverwort stem. In the Arnelliaceae, this comprises a central medullary strand; in the Lophoziaceae and Scapaniaceae, the ventral medulla contains a mosaic of infected and noninfected cells. In the latter, pegs of host wall material overgrow penetrating hyphae. Electron microscopy revealed that all of the endophytes have straight imperforate parenthesomes typical of heterobasidiomycetes. The fungi form hyphal coils that outlive the host cytoplasm, and digestion of the mycobionts, as seen in Aneuraceae and orchidaceous mycorrhizas, are absent. Closely similar mosaic infection patterns in Lophoziaceae and Scapaniaceae strenghten the link between the two families based on molecular data, but the present cross-infection and ultrastructural data indicate that the Calypogeia endophyte is ascomycetous rather than a member of the Sebacinaceae as reported previously. The distribution of basidiomycete associations in liverworts suggests that these probably arose several times and are more recent in origin than associations with glomeromycotean fungi.
Elatine ojibwayensis sp.nov., une nouvelle espèce d’Elatinaceae et revue des Elatinaceae du Québec
Authors: Garneau Michelle
Published: September 2006

Une nouvelle espèce de la famille des Elatinaceae, l’ Elatine ojibwayensis Garneau sp.nov., est décrite à partir de spécimens récoltés dans le nord du Quebec. Cette nouvelle espèce représente le seul Elatine à fleurs tétramères dans l’est de l’Amérique du Nord. Sa répartition connue est restreinte au centre du Quebec entre 50° 05′ N et 55° 11′ N, sur le versant québécois des baies de James et d’Hudson. Un traitement du genre Elatine au Quebec est présenté, incluant la description, la carte de répartition de chaque espèce, ainsi qu’une clef de détermination.
Susceptibility of endophyte-infected grasses to winter pathogens (snow molds)
Authors: Wäli Piippa R. , Helander Marjo , Nissinen Oiva , Saikkonen Kari
Published: September 2006

Neotyphodium endophytes are suggested to be mutualistic symbionts of grasses and regarded as potential biological plant protection agents. We examined the effects of the Neotyphodium endophyte of meadow ryegrass on snow molds in vitro with dual cultures of endophyte and Typhula ishikariensis , and on grass–snow mold interactions in vivo in a greenhouse and in a field experiment. In dual cultures, the endophytes formed an inhibition zone and retarded the growth of T. ishikariensis. In the field experiment, however, the endophyte-infected (E+) meadow ryegrasses were more susceptible to T. ishikariensis than the endophyte-free (E–) grasses. Endophyte infection increased the winter damage of grasses both in greenhouse and in field conditions. After winter, the growth of E+ grasses exceeded the growth of E– plants in the field experiment, indicating the marked tolerance of E+ grasses against winter damage. We detected differences in growth and pathogenesis between the different T. ishikariensis strains and found meadow ryegrass cultivar–endophyte status interaction in the growth of meadow ryegrasses, which highlight the effects of the genetic background of the participants on endophyte–grass–snow mold interactions.
Hailstorm damage promotes aspen invasion into grassland
Authors: Peltzer Duane A. , Wilson Scott D.
Published: September 2006

Global warming is widely thought to promote the dominance of grasslands over woody vegetation, and shift the location of ecotones. In contrast, forest vegetation along the northern edge of the North American Great Plains has migrated southward over the past century into areas dominated by native grassland. Because climate change is also predicted to increase storm frequency and intensity, we quantified the impacts of an intense hailstorm on woody and herbaceous species in native grassland in the northern Great Plains of North America. The hailstorm disturbance killed or damaged mature stems of the dominant tree, aspen ( Populus tremuloides Michx.), but damaged aspen stands subsequently invaded ca. 10 m into neighbouring grassland. Damaged aspen stands also produced up to 20-fold more new stems having 67-fold higher total biomass compared with relatively undisturbed stands. Grasses and lichens suffered much higher rates of biomass removal (60%–76%) than did shrubs (6%–8%) immediately following the storm. The disturbance-mediated recruitment of clonal woody plants, and the unexpected sensitivity of grasses and lichens to this disturbance, may contribute to the counterintuitive expansion of trees into grasslands under a regime of increased storm frequency that is not predicted by simple ecosystem responses to warming.
Long-term climate and weather patterns in relation to crop yield: a minireview
Authors: McKeown A.W. , Warland J. , McDonald M.R.
Published: September 2006

It is accepted knowledge that weather affects yields and climate dictates which crops will grow in a region. Specific weather events, such as drought or hail, that affect yield or quality, are known, as are the general climatic conditions required for groups of crops such as cool season vegetables or tropical crops. However, more precise information on how changes in long-term weather and climate influence the yield of specific vegetable crops is not available. Studies of yield over long periods have the advantage of reflecting the combined effects of numerous environmental variables, including climate effects on physiological stress, pests, and diseases. A study of yields of cool season vegetable crops in Ontario revealed that a decrease in yields is related to an increase in the number of hot days with maximum temperatures over 30 °C. A clear warming trend in Ontario weather is evident, beginning in the mid-1980s, with increasing numbers of hot days and more variable temperatures from year to year. Furthermore, yields of cole crops declined by 10% for every 10 d with temperatures >30 °C in the growing season. Several other studies on agronomic crops worldwide show reductions in yield resulting from warmer temperatures. For example, in a study of rice in the Philippines, yield was reduced by 10% for every 1 °C increase in minimum temperature during the dry season. Methods for evaluating long-term climate effects on crop yield are discussed.
Spherical Couette flow of Oldroyd 8-constant model Part I. Solution up to the second-order approximation
Authors: Hassan A Abu-El
Published: September 2006

The steady flow of an incompressible Oldroyd 8-constant fluid in the annular region between two spheres, or so-called spherical Couette flow, is investigated. The inner sphere rotates with anangular velocity Ω about the z-axis, which passes through the center of the spheres, while the outer sphere is kept at rest. The viscoelasticity of the fluid is assumed to dominate the inertia such that the latter can be neglected in the momentum equation. An analytical solution is obtained through the expansion of the dynamical variables in a power series of the dimensionless retardation time. The leading velocity term denotes the Newtonian rotation about the z-axis. The first-order term results in a secondary flow represented by the stream function that divides the flow region into four symmetric parts. The second-order term is the viscoelastic contribution to the primary viscous flow. The first-order approximation depends on the viscosity and four of the material time-constants of the fluid. The second-order approximation depends on the eight viscometric parameters of the fluid. The torque acting on the outer sphere has an additional term due to viscoelasticity that depends on all the material parameters of the fluid under consideration. For an Oldroyd-B fluid this contributed term enhances the primary torque but in the case of fluids with higher elasticity the torque components may be enhanced or diminished depending on the values of the viscometric parameters.PACS Nos.: 47.15.Rq
Rigidité diélectrique d'un interface gazsupport avec contaminant métallique dans l'air sec et ses mélanges avec le SF6
Authors: Imano Adolphe Moukengué
Published: September 2006

In this paper, we conduct a series of experiments aimed at analysing the dielectric properties of compressed dry air, and some SF6air mixtures up to 700 kPa, under application of AC 50 Hz and lightning impulse (LI) 1.2 μs/50 μs voltage. The investigations were carried out by using a cylindrical spacer model with an adhering particle on the surface under homogenous field conditions. We measure the partial discharges (PD) propagation characteristics under LI voltage stress, as well as the PD inception voltage and the flashover voltage for the contaminated particle. We also investigate the surface charge accumulation on the spacer surface under contaminated particle conditions. The results of the experiments reveal the influence a conducting particle has on the determined flashover field strength, for SF6air mixtures compared with pure, compressed dry air. This influence is discussed for different particle lengths, but also for three different particle positions in the gap. Pure dry air achieves a higher dielectric strength when the particle gets into contact with the high voltage electrode, under negative LI voltage stress. The same result is obtained for the SF6air mixtures, when the particle is located in the middle of the gap, as floating electrode on the spacer surface. The reported results contribute to the improvement of the models of breakdown through the interface gassolid isolator. The application of these models should offer the possibility for considering the use of dry air, or its mixtures with SF6 which, normally have a lower relative global warming potential than pure SF6.[Traduit par la Rédaction]
Early above- and below-ground responses of subboreal conifer seedlings to various levels of deciduous canopy removal
Authors: Claveau Yves , Comeau Philip G , Messier Christian , Kelly Colin P
Published: September 2006

We examined the growth of understory conifers, following partial or complete deciduous canopy removal, in a field study established in two regions in Canada. In central British Columbia, we studied the responses of three species (Pseudotsuga menziesii var. glauca (Beissn.) Franco, Picea glauca (Moench) Voss × Picea engelmannii Parry ex Engelm., and Abies lasiocarpa (Hook.) Nutt.), and in northwestern Quebec, we studied one species (Abies balsamea (L.) Mill.). Stem and root diameter and height growth were measured 5 years before and 3 years after harvesting. Both root and stem diameter growth increased sharply following release but seedlings showed greater root growth, suggesting that in the short term, improvement in soil resource capture and transport, and presumably stability, may be more important than an increase in stem diameter and height growth. Response was strongly size dependent, which appears to reflect greater demand for soil resources as well as higher light levels and greater tree vigour before release for taller individuals. Growth ratios could not explain the faster response generally attributed to true fir species or the unusual swift response of spruces. Good prerelease vigour of spruces, presumably favoured by deciduous canopies, could explain their rapid response to release.
Are mineral soils exposed by severe wildfire better seedbeds for conifer regeneration?
Authors: Kemball Kevin J , Wang G. Geoff , Westwood A Richard
Published: September 2006

We examined jack pine (Pinus banksiana Lamb.), black spruce (Picea mariana (Mill.) BSP), and white spruce (Picea glauca (Moench) Voss) seed germination and seedling recruitment in aspen (Populus tremuloides Michx.) and conifer mixedwood stands following the 1999 Black River fire in southeastern Manitoba, Canada. Three postfire seedbed types were tested: scorched (surface litter only partially consumed), lightly burned (surface litter consumed with little or no duff consumption), and severely burned (complete consumption of litter and duff exposing mineral soil). Seeds were sown in 1999, 2000, and 2001, and each cohort was monitored for 3 years. In 1999, severely burned seedbeds had poor germination, while scorched seedbeds had the highest germination. The reverse was true in 2001. After the first growing season, continued survival of seedlings was greater on severely burned seedbeds for all three cohorts. However, better survival on severely burned seedbeds was not sufficient to overcome poor germination in 1999 and 2000. When using artificial seeding to promote conifer regeneration, we recommend a delay of one full year after a severe spring fire for jack pine and two full years for black spruce and white spruce on boreal aspen and conifer mixedwood sites.
The effect of competition from different weed species on the growth of Betula pendula seedlings
Authors: Willoughby Ian , Clay David V , Dixon Fiona L , Morgan Geoff W
Published: September 2006

The identification of less competitive weed species and infestation rates might allow weeding operations to be better targeted, help conserve local plant biodiversity, and facilitate reductions in the amount of herbicide used to achieve woodland regeneration. Therefore, the effect of competition from pure stands of Cirsium vulgare (Savi) Ten., Epilobium ciliatum Raf., Holcus lanatus L., Poa annua L., and Persicaria maculosa Gray on Betula pendula Roth was investigated over 2 years. All weed species reduced tree growth significantly compared with weed-free plots, but there were no significant differences among species. When Lolium perenne L., Rumex obtusifolius L., and Cirsium vulgare were established at four densities in plots containing newly planted B. pendula over a 1-year period, all weed species reduced tree growth, but Lolium perenne was the most competitive. Weed density had no significant effect, indicating that even sparse weed growth can have a major impact on tree performance. None of the treatments affected B. pendula survival. These results confirm the inhibitory effects of a range of weed species on tree growth, but not survival, and the capacity of B. pendula to recover in the second year after planting from an initial check in growth. Percent cover was a good explanatory variable for models developed to describe the effects of weeds on tree growth, and preliminary competition indices for the different species are presented.
Correlation between clonal means and open-pollinated seedling progeny means and its implications for radiata pine breeding strategy
Authors: Kumar Satish
Published: September 2006

Open-pollinated (OP) offspring of individual genotypes are commonly used for estimating their breeding values in recurrent selection programmes. Alternatively, vegetative propagules of individual genotypes could also be used to evaluate their relative performance. However, the mean for the vegetative propagules of a genotype represents an estimate of its total genotypic value, and it may or may not be closely related to the general combining ability. The main objective of this study was to correlate the performance of a number of clones, propagated by fascicle cuttings in a clonal test, with the performance of their OP offspring, planted in a progeny test. The empirical correlations between performance of a genotype, given as the mean of its ramets, and performance of the genotypes's offspring, given as the mean of its OP progeny, were 0.56, 0.63, 0.81, and 0.09 for stem diameter, stem straightness scores, branch cluster frequency scores, and malformation scores, respectively. The theoretical expectations of these correlations were 0.55, 0.69, 0.81, and 0.24, respectively. The size of the correlation largely depended on the genetic control of the trait concerned. Implications of these results on the radiata pine (Pinus radiata D. Don) breeding strategy were discussed.
Drag coefficients and crown area estimation of red maple
Authors: Kane Brian , Smiley E Thomas
Published: September 2006

During storms, shade trees may fall as a result of excessive drag; anticipating such events has obvious benefits. We measured the drag of red maples (Acer rubrum L.) up to 5 m tall in winds up to 20 m/s. Drag correlated with tree mass, height and crown frontal area as previously shown in conifers and small deciduous trees tested in wind tunnels. Drag coefficients, based on still-air frontal areas, decreased, whereas drag-induced bending moments increased as wind speed increased. Drag predictions based on approximating canopies as simple shapes like triangles and rectangles did not accurately reflect measured drag, although manipulating drag coefficients can allow drag predictions based on simple shapes.
Incorporating genetic parameters into a loblolly pine growth-and-yield model
Authors: Adams Joshua P , Matney Thomas G , Land Jr. Samuel B , Belli Keith L , Duzan Jr. Howard W
Published: September 2006

Differences in survival, diameter, height (site index), and stem profile among eight North Carolina half-sib families and one Mississippi–Alabama commercial check of loblolly pine (Pinus taeda L.) at three spacings over 17 years were evaluated for effects on a growth-and-yield model. Actual stand volume at age 17 was determined from a 100% measurement of all trees. This volume was compared with predicted volumes from age nine measurements using (i) the unmodified model and (ii) the model after modifications for family differences. Modifications to the model included family-specific site indices for height differences and family-specific regression functions for each of the other traits. The unmodified model resulted in an underestimate of actual stand volume by 31%. Adjustments for family differences in dominant height (site index), survival, or profile had little effect on this bias. Insertion of family-specific regressions for stem profile and site index in combination with survival-diameter density effects greatly reduced the bias and provided the best estimates of future stand volumes.
Emergence of balsam fir seedlings under increasing broadleaf litter thickness
Authors: Parent Sylvain , Walsh Denis , Simard Marie-Josée , Morin Hubert , Gagnon Réjean
Published: September 2006

Balsam fir (Abies balsames (L.) Mill.) seeds dispersed in autumn–winter can be covered by many layers of broadleaves when they germinate under deciduous trees during the following growing season. Our goal was to test the effect of seed density, broadleaf litter thickness, and substrate type on emergence, morphology, and dry mass allocation of balsam fir. The greenhouse experiment included three seeding densities, four litter thicknesses covering the seeds, and two substrate types. The broadleaf mixture was composed of white birch (Betula payrifera Marsh.), trembling aspen (Populus tremuloides Michx.), and pin cherry (Prunus pensylvanica L.f.) collected on the forest floor of a 30-year-old postfire stand. Seed density had no effect on emergence from under broadleaf litter. Emergence was lower on the litter substrate than on potting soil. Seedling emergence and vigor declined as broadleaf thickness increased. Depending on substrate type, emergence was reduced by 20% (leaf litter substrate) to 28% (potting soil) when seeds were covered by 1.4–2.0 cm of broadleaves. An overtopping layer of 2.5–3.0 cm reduced emergence by 57%. Balsam firs emerging from under broadleaf litter allocated more dry mass to longer and thinner hypocotyls at the expense of cotyledon and root growth, albeit seeded on potting soil. This study identifies biomechanical constraints that severely reduce early seedling vigour suggesting that in situ survival under broadleaf litter is very low.