bluuebunny/crossref_metadata_2025 huggingface dataset:
DIFFERENTIAL (HOST‐SPECIFIC) ACCUMULATION OF ZOOSPORES OF PYTHIUM ON ROOTS OF GRAMINACEOUS AND NON‐GRAMINACEOUS PLANTS
Authors: MITCHELL R. T. , DEACON J. W.
Published: May 2006

Summary

Zoospores of Pythium graminicola Subramanian and P. arrhenomanes Drechs., which characteristically infect the Gramineae, differed from spores of P. aphanidermatum (Edson) Fitzp. and P. ultimum Trow, which have wide host ranges, by accumulating to a greater degree on roots of graminaceous as compared with non‐graminaceous plants. These differential responses occurred with wild plants collected from field sites or grown in a glasshouse, but not with cultivated cereals and dicotyledonous plants (Antirrhinum majus L. and Lycopersicon esculentum Mill.) grown in a glasshouse. Differential responses involved mainly encystment and accumulation of encysted spores, rather than taxis.

Root mucigel was implicated in zoospore accumulation. Host‐differences in this respect did not occur with damaged roots; treatment of roots with methylene blue or periodate (but not alcian blue or Calcofluor) prevented or reduced zoospore encystment without markedly affecting accumulation of motile zoospores.
PHYSIOLOGICAL AND ANATOMICAL ASPECTS OF PHOTOSYNTHESIS OF TWO AGROSTIS SPECIES AT A SUB‐ANTARCTIC ISLAND
Authors: PAMMENTER N. W. , DRENNAN PHILLIPPA M. , SMITH V. R.
Published: May 2006

Summary

Leaf anatomy, rates of photosynthesis, leaf N, chlorophyll, RuBP carboxylase and nitrate reductase were studied on the indigenous Agrostis magellanica Lam. and the invasive alien Agrostis stolonifera L. on Marion Island (46° 54′ S, 37° 45′ E). Leaves of A. magellanica were more deeply ridged, thicker and more sclerophyllus than those of A. stolonifera. Mesophyll cells of A. magellanica were larger but the number of cells per unit leaf area and the total area of chloroplast per unit leaf area were the same for the two species. Maximum CO2 assimilation rates for the two species did not differ (mean maxima of 9.5 and 9 μmol CO2 m−2s−1for A. magellanica and A. stolonifera respectively). At low photon flux densities, A. stolonifera showed a greater response of CO2 assimilation to photon flux density. A. magellanica exhibited temperature‐dependent photoinhibition. Leaf N, chlorophyll and RuBP carboxylase on a fresh or dry weight basis were higher in A. stolonifera but on a leaf area basis there was little difference between the species. The competitive ability of A. stolonifera on Marion Island may be related to its response to low photon flux densities or to its carbon allocation patterns (less sclerophyllous tissue means that a greater leaf area may be produced per unit carbon fixed). The lack of support tissue may limit it to sites partly sheltered from frequent gale force winds.
RE‐INVESTIGATION OF SECRETORY CAVITY DEVELOPMENT IN LYSIMACHIA (PRIMULACEAE)
Authors: LERSTEN NELS R.
Published: May 2006

Summary

Nineteenth century studies described Lysimachia cavities as schizogenous, but Guttenberg (1928) reported them as only being schizogenous initially. Inner epithelial cell walls then swelled and dissolved in mucilage secreted into the cavity. Later, as a gradually solidifying resin accumulated, epithelial cells reportedly formed a new and cellulosic cell wall. My re‐examination of cavity development in Lysimachia nummularia L., using a resin embedding method, revealed only typical schizogenous development, thus refuting Guttenberg's interpretation and supporting earlier workers.
SOIL MOISTURE INFLUENCES COLONIZATION OF PRAIRIE CORDGRASS (SPARTINA PEC TIN ATA LIND.) BY VESICULAR‐ARBUSCULAR MYCORRHIZAL FUNGI
Authors: ANDERSON ROGER C. , EBBERS BERT C. , LIBERTA ANTHONY E.
Published: May 2006

Summary

We examined mycorrhizal development in prairie cordgrass (Spartina pectinate Lind.), a mycorrhizal plant that typically occupies wet habitats, under different soil moisture conditions. The five experimentally induced soil moisture conditions ranged from continuous saturation to allowing soil moisture tensions to reach – 15 bars and then saturating the soil 48 h later.

Colonization by vesicular‐arbuscular mycorrhizal (VAM) fungi occurred under all experimental conditions but was significantly greater when plants were grown under conditions of 24 h saturation followed by 48 h of drainage than under any other moisture regime. There was a significant negative correlation between VAM fungal colonization and the weight of the rhizome‐tiller units used to propogate experimental plants. Plant growth was not significantly affected by treatment conditions and there were no significant correlations between measured plant growth response and VAM colonization.
ECTOMYCORRHIZAS OF TROPICAL ANGIOSPERMOUS TREES
Authors: ALEXANDER I. J. , HÖGBERG P.
Published: May 2006

Summary

Details are presented of ectomycorrhizas in seventeen genera of tropical angiospermous trees from six families. Mycorrhizas of Intsia, Melaleuca, Monotes, Neea, Tristania and Vateria are figured for the first time. Overall, the tropical mycorrhizas are of a smaller diameter than is typical for those of temperate angiosperm trees but the sheaths are thicker and the fungus can form up to about 80% by weight of the dual organ. Our observations do not support the notion of a higher degree of host/fungus specificity in the tropics than in the temperate zones.
STUDIES ON THE TOLERANCE TO SULPHUR DIOXIDE OF GRASS POPULATIONS IN POLLUTED AREAS
Authors: WILSON G. B. , BELL J. N. B.
Published: May 2006

Summary

The evolution of tolerance to sulphur dioxide (SO2) under differing degrees of selective pressure over the same period of time was investigated in Festuca rubra L. and Dactylis glomerata L. along a transect away from a point source (a smokeless fuel factory) in northern England. Populations of both species were sampled from eight sites along the 2 km transect, starting close to the factory. All populations were screened for relative sensitivity to acute injury, assessed as degree of leaf damage after fumigation with a high concentration of SO2. In the case of F. rubra, relative sensitivity to chronic injury was also determined, on the basis of changes in growth in response to a prolonged fumigation with a moderate concentration of SO2. Festuca rubra showed a clear cline of decreasing tolerance to acute injury with distance from the point source, but no such pattern was apparent for D. glomerata. Although the chronic fumigation produced reductions in various growth parameters for F. rubra, there was no clear indication of changes in tolerance along the transect. The pattern of evolution of acute SO2 tolerance in F. rubra is discussed in relation to the selective pressures imposed at different sites by combinations of high and low level emissions from the factory. The occurrence of tolerance to acute, but not chronic injury is in agreement with earlier work by the authors, which suggested that there was greater potential for the rapid evolution of the former at polluted sites.
REGENERATION OF SPHAGNUM
Authors: CLYMO R. S. , DUCKETT J. G.
Published: May 2006

Summary

When disc‐shaped horizontal slices of peat cores, three from a bog in mid‐Wales and three from a bog in Hampshire, were kept for several months in a saturated atmosphere in a cool greenhouse numerous new shoots of Sphagnum papillosum (Lindb. S. magellanicum Brid. and S. recurvum P. Beauv. were produced.

The new shoots arose on peat discs from at least 30 cm below the surface and water table and from regions in which the Sphagnum appeared to be brown and dead. A timescale, inferred from the cumulative dry mass and the peak in 137Cs concentration (which was assumed, conservatively, to reflect the 1963 peak influx), indicates that the matrix of the deepest discs from which new shoots arose was from 25 to perhaps 60 years old.

Many of the new shoots of Sphagnum arose as innovations from the outer cortex of buried stems. In most cases the first leaves on these had the usual dimorphic leaf cell pattern. Other shoots, which initially produced leaves with monomorphic cells, arose from protonemata, comprising irregularly lobed plates of tissue and sparsely branched filaments with oblique cross‐walls. A few of the protonemata arose from old stems, a feature not reported before, but the vast majority had no attachment to old plants and are thought to have grown from spores.

Light and air were necessary if new shoots were to appear. But very few innovations or protonemata were found in the green discs from near the surface of the core. This suggests some kind of hormonal control of innovations akin to apical dominance in vascular plants and a more general allelopathic inhibition of spore germination and protonemal growth by green Sphagnum.

Fern gametophytes of at least two taxa (Dryopteris‐like and Pteridium‐like) grew on the peat discs with distribution patterns similar to those of new Sphagnum shoots. Seedlings of five taxa of vascular plants – all species growing close to the core‐sites – appeared on the peat discs but much more erratically than Sphagnum and the ferns. Stems of five species of leafy liverwort, presumed to have been derived from subterranean axes rather than from gemmae or spores, were also recorded, but no other bryophytes were seen.

The discovery that morphogenesis in Sphagnum is far more fluid than hitherto assumed has far‐reaching physiological, ecological and possibly genetical implications. The development of protonemata under semi‐natural conditions, recorded here for the first time, confounds the results of culture experiments which had indicated that Sphagnum protonemata were unlikely to grow on peat.
Political participation and procedural utility: An empirical study
Authors: STUTZER ALOIS , FREY BRUNO S.
Published: May 2006

Abstract.  Democracy can be characterized by policy outcomes as well as governmental processes. In this article, it is argued that people have preferences about both aspects and that they derive utility from the processes involved in decision making over and above the utility gained from outcomes. The authors study political participation possibilities as an important source of procedural utility. To distinguish between outcome and process utility, they take advantage of the fact that nationals can participate in political decision making, while foreigners are excluded and thus cannot enjoy the respective procedural utility. Utility is assumed to be measurable by individually reported subjective well‐being. As an additional indicator for procedural utility, reported belief in political influence is analyzed.
Effects of Single‐Site Versus Biventricular Epicardial Pacing on Myocardial Performance in an Immature Animal Model of Atrioventricular Block
Authors: COJOC ANCA , REEVES JAMES G. , SCHMARKEY LAURA , STRIEPER MARGARET J. , JOYNER RONALD W. , WAGNER MARY B. , CAMPBELL ROBERT M. , VINTEN‐JOHANSEN JACOB , FRIAS PATRICIO A.
Published: May 2006

Introduction:  Single‐site ventricular pacing results in dyssynchronous ventricular activation and may contribute to ventricular dysfunction. We evaluated epicardial biventricular (BiV) pacing as a means of maintaining synchronous ventricular activation in an acute piglet model of AV block with normal ventricular anatomy and function.

Methods and Results: We used left ventricular (LV) impedance catheters and tissue Doppler imaging to assess the cardiodynamics of immature piglets (n = 6, 33–78 days, 9.35 ± 0.85 kg). Following catheter ablation of the AV node, a pacemaker was programmed 20 beats per minute above the intrinsic atrial rate. The animals were paced at 5‐minute intervals via the following AV sequential configurations: Right atrial appendage (RA)‐RV apex (RVA), RA‐LV apex (LVA), and RA‐biventricular (RVA/LVA). RA‐RVA was the experimental control. LV systolic mechanics, measured by the slope of the end‐systolic pressure–volume relationship (Ees), increased with BiV pacing (12.8 ± 3.4 mmHg/mL, P < 0.02) or single‐site LVA pacing (10.6 ± 3.4 mmHg/mL, P < 0.05) compared with single‐site RVA pacing (8.3 ± 1.4 mmHg/mL). QRS duration lengthened compared with sinus rhythm (42 ± 8 msec) with either RVA (56 ± 9 msec, P < 0.02) or LVA (54 ± 7 msec, P < 0.03), but not with BiV (48 ± 7 msec, P = 0.08) pacing. Tissue Doppler imaging showed LV dyssynchrony with RVA (septal‐to‐lateral delay 46.0 ± 51.7 msec), with return toward normal with LVA (−9.6 ± 33.6 msec, P < 0.04) or BiV (−4.1 ± 33.8 msec, P < 0.04) pacing.

Conclusions: In this acute immature piglet model of AV block, LV performance improved with single‐site pacing from the LVA and BiV pacing (RVA/LVA), as compared with single‐site pacing from the RVA. These changes correlated with tissue Doppler indices of mechanical synchrony, though not necessarily with QRS duration.
Fibrillating Areas Isolated within the Left Atrium after Radiofrequency Linear Catheter Ablation
Authors: ROSTOCK THOMAS , ROTTER MARTIN , SANDERS PRASHANTHAN , JAÏS PIERRE , HOCINI MÉLÈZE , TAKAHASHI YOSHIHIDE , SACHER FRÉDERIC , JÖNSSON ANDERS , O'NEILL MARK D. , HSU LI‐FERN , CLÉMENTY JACQUES , HAÏSSAGUERRE MICHEL
Published: May 2006

Introduction: Nonpulmonary vein sources have been implicated as potential drivers of atrial fibrillation (AF). This observational study describes regions of fibrillating atrial tissue isolated inadvertently from the left atrium (LA) following linear catheter ablation for AF.

Methods and Results: We report four patients with persistent/permanent AF who underwent pulmonary vein isolation with additional linear lesions and who presented with recurrent AF (mean AF cycle length [AFCL] 175–270 ms). Further catheter ablation resulted in the inadvertent electrical isolation of significant areas of the LA in which AF persisted at the same AFCL as was measured prior to disconnection, despite the restoration of sinus rhythm (SR) in all other left and right atrial areas, strongly suggesting that these islands were driving the remaining atria into fibrillation. The disconnected areas were located in the lateral LA, including the left atrial appendage (LAA) in three patients (limited to the LAA in one) and in the posterior LA in one patient. These isolated fibrillating regions represented 15–24% of the global LA surface, as estimated by electroanatomic mapping.

Conclusion: Fibrillation can be maintained within electrically isolated regions of the LA following catheter ablation of AF, demonstrating the importance of atrial drivers in the maintenance of AF. Further mapping of these drivers is needed to characterize their mechanism and thereby allow for a more specific ablation strategy.
Bone healing and graft resorption of autograft, anorganic bovine bone and β‐tricalcium phosphate. A histologic and histomorphometric study in the mandibles of minipigs
Authors: Jensen Simon Storgård , Broggini Nina , Hjørting‐Hansen Erik , Schenk Robert , Buser Daniel
Published: May 2006

Objective: The purpose was to qualitatively and quantitatively compare the bone formation and graft resorption of two different bone substitutes used in both orthopedic and oral surgery, with autogenous bone as a positive control.

Materials and methods: Three standardized bone defects were prepared in both mandibular angles of 12 adult minipigs. The defects were grafted with either autograft, anorganic bovine bone (ABB), or synthetic β‐tricalcium phosphate (β‐TCP). Sacrifice was performed after 1, 2, 4, and 8 weeks for histologic and histomorphometric analysis.

Results: At 2 weeks, more new bone formation was seen in defects filled with autograft than with ABB (P∼0.0005) and β‐TCP (P∼0.002). After 4 weeks, there was no significant difference between β‐TCP and the two other materials. Defects grafted with ABB still exhibited less bone formation as compared with autograft (P∼0.004). At 8 weeks, more bone formation was observed in defects grafted with autograft (P∼0.003) and β‐TCP (P∼0.00004) than with ABB. No difference could be demonstrated between β‐TCP and autograft. β‐TCP resorbed almost completely over 8 weeks, whereas ABB remained stable.

Conclusion: Both bone substitutes seemed to decelerate bone regeneration in the early healing phase as compared with autograft. All defects ultimately regenerated with newly formed bone and a developing bone marrow. The grafting materials showed complete osseous integration. Both bone substitutes may have a place in reconstructive surgery where different clinical indications require differences in biodegradability.
Treatment of scabies with 5% permethrin cream: results of a German multicenter study
Authors: Hamm Henning , Beiteke Ulrike , Höger Peter H. , Seitz Cornelia S. , Thaci Diamant , Sunderkötter Cord
Published: May 2006

Background: Until recently, no prescription drug containing permethrin for the therapy of scabies was available on the German market.Therefore, a 5% permethrin cream formulation (InfectoScab® 5%) was tested in a single‐arm multi‐center study including adults and children from 3 months of age with proven scabies.

Patients and Methods: On day 0, patients were treated once with permethrin cream in the study center. Control examinations including dermatoscopy were performed on day 14±2 and on day 28±3. Patients who were not considered cured or who had contact to individuals with untreated scabies received one further treatment with permethrin cream on day 14±2. Itching and local tolerability of the cream were documented in patients' diaries. Side effects were assessed by history, skin inspection and evaluation of patients' notes.

Results: 106 patients in 13 centers were enrolled in the study. Their mean age was 29.2 years (range, 141 days to 71.9 years); 34% of them were children or adolescents. 78.3% of patients were either severely (3 body sites) or very severely (4–5 sites) affected. The cure rate on day 28±3 was 95.1% (95% confidence interval, 91.0–99.3%). Pruritus declined markedly and continuously. In general, the cream was well tolerated; side effects were almost invariably mild.

Conclusions: Our results support the efficacy and safety of 5% permethrin cream in adults, children and infants suffering from scabies. These results have contributed to the approval of InfectoScab® 5% in Germany for the treatment of scabies in October 2004.
Intracavernous Injections of Prostaglandin E1 for Erectile Dysfunction: Patient Satisfaction and Quality of Sex Life on Long-Term Treatment
Authors: Alexandre Benjamin , Lemaire Antoine , Desvaux Pierre , Amar Edouard
Published: May 2006

Introduction

Since the availability of oral type 5 phosphodiesterase (PDE5) inhibitors for the treatment of erectile dysfunction (ED), patients’ views on the use of intracavernous injections (ICI) of prostaglandin E1 (PGE1) may have changed.

Aim

To assess the satisfaction of patients with long-term ICI.

Methods

Patients with ED (>18 years old) who had used ICI of PGE1 for at least 3 months were asked to complete the “EASY” (Evaluation de l’Acceptation des injectionS dans la dYsfonction érectile) questionnaire.

Main Outcome Measures

Overall patient satisfaction with ICI, impact on quality of life, ease of use, satisfaction with the quality of erections, and perceived partner satisfaction.

Results

Overall, 596 questionnaires met our inclusion criteria. Mean patient age was 62.1 years, mean duration of ED was 61 months, and mean duration of ICI treatment was 35 months. Before using ICI, 43% of patients had taken at least one PDE5 inhibitor; 81% discontinued PDE5 for want of efficacy. The overall satisfaction rate with ICI was 78.3%. ICI met expectations each time in 78.6% of patients and at least half the time in 90% of patients; 86% were ready to recommend ICI to friends. Patients noted improvements in their sex life (70.1%), relationship with their partner (50%), quality of life (44.8%), and confidence in attempting sexual intercourse (80.3%). The mean number of injections was 4.4 per month. Most patients (81.1%) found the injections easy to use. The mean score for pain on injection was 2.09/10 and for pain on erection was 2.15/10. Three-quarters of patients (73.1%) thought that their partners were satisfied with ICI.

Conclusion

Patients on long-term ICI/PGE1 can recover a very satisfying sex life. ICI met patients’ expectations in terms of efficacy, ease of use, tolerance, and improved sex life. These results should encourage physicians and patients to use ICI when PDE5 fails, is not well tolerated, or is contraindicated.
Upsizing of Inflatable Penile Implant Cylinders in Patients with Corporal Fibrosis
Authors: Wilson Steven K. , Delk John R. , Mulcahy John J. , Cleves Mario , Salem Emad A.
Published: May 2006

Introduction

Placement of an inflatable penile prosthesis in a patient with scarred corporal bodies secondary to priapism or removal of a previously infected implant is a formidable surgical challenge; use of downsized implants has improved chances of successful reimplantation. Nevertheless, patients are frequently dissatisfied with the resulting short penises.

Aim

This study investigates the use of downsized inflatable penile prosthesis cylinders as tissue expanders in patients with corporal fibrosis.

Main Outcomes Measures

Corporal length and width were calibrated before implantation of downsized prostheses and after 1 year of their use as tissue expanders.

Methods

Thirty-seven patients had insertion of Mentor Narrow Base (18), AMS CXM (9), or AMS CXR (10) into scarred corporal bodies. Etiology was previously infected and removed implant (29) or priapism (8). In each of these cases it was not possible to dilate to 12 mm in order to place standard-sized cylinders. Patients were encouraged to inflate their implant for up to 3 hours daily. After several months intracorporal stretching occurred. The patients were reoperated; corporal length and width were recalibrated.

Results

Upon reoperation, it was possible to pass dilators of 12 mm width proximally allowing the substitution of standard-sized AMS 700 CX (23), Mentor Alpha 1 (10), or Mentor Titan (2). Additionally, corporal length measurements in the previously infected patients increased an average of 2.2 cm allowing placement of longer cylinders. Although priapism patients did not show this phenomenon of corporal lengthening, the implant space widened enough to permit replacement with standard-size cylinders improving girth, rigidity, and appearance.

Conclusions

Wider and sometimes longer cylinders can be substituted in patients with corporal fibrosis that required implantation with downsized cylinders because of fibrotic corpora. Prolonged inflation over an 8- to 12-month period results in expansion of the cylinder cavity, permitting standard-sized cylinders in all patients.
Effective case presentations—An important clinical skill for nurse practitioners
Authors: Coralli Connie H.
Published: May 2006

Comment from the Editor

Over the years we have had numerous requests to reprint this article which first appeared in 1989, volume 1, issue 2. The author, Connie Coralli, is no longer working in nursing, but she was happy to grant permission for us to reprint this timeless piece.

Effective case presentations are an important component of the nurse practitioner’s skills, yet very little literature exists to guide the development of this skill, and frequently little priority is given to teaching this skill during the education of the nurse practitioner. This report discusses the importance of effective case presentations, describes the organization of the presentation, and outlines the appropriate information to be included. The main components of a case presentation—introduction, history of the present illness, physical examination, diagnostic studies, differential diagnosis, management, and summary of the case—are discussed in detail. Examples of a formal and an informal case presentation are presented and used to illustrate key points in the text.
Signaling Interactions between the Aerotaxis Transducer Aer and Heterologous Chemoreceptors in
Escherichia coli
Authors: Gosink Khoosheh K. , del Carmen Burón-Barral Maria , Parkinson John S.
Published: May 2006

Aer, a low-abundance signal transducer in
Escherichia coli
, mediates robust aerotactic behavior, possibly through interactions with methyl-accepting chemotaxis proteins (MCP). We obtained evidence for interactions between Aer and the high-abundance aspartate (Tar) and serine (Tsr) receptors. Aer molecules bearing a cysteine reporter diagnostic for trimer-of-dimer formation yielded cross-linking products upon treatment with a trifunctional maleimide reagent. Aer also formed mixed cross-linking products with a similarly marked Tar reporter. An Aer trimer contact mutation known to abolish trimer formation by MCPs eliminated Aer trimer and mixed trimer formation. Trimer contact alterations known to cause epistatic behavior in MCPs also produced epistatic properties in Aer. Amino acid replacements in the Tar trimer contact region suppressed an epistatic Aer signaling defect, consistent with compensatory conformational changes between directly interacting proteins. In cells lacking MCPs, Aer function required high-level expression, comparable to the aggregate number of receptors in a wild-type cell. Aer proteins with clockwise (CW)-biased signal output cannot function under these conditions but do so in the presence of MCPs, presumably through formation of mixed signaling teams. The Tar signaling domain was sufficient for functional rescue. Moreover, CW-biased lesions did not impair aerotactic signaling in a hybrid Aer-Tar transducer capable of adjusting its steady-state signal output via methylation-dependent sensory adaptation. Thus, MCPs most likely assist mutant Aer proteins to signal productively by forming collaborative signaling teams. Aer evidently evolved to operate collaboratively with high-abundance receptors but can also function without MCP assistance, provided that it can establish a suitable prestimulus swimming pattern.
Increased Persistence in
Escherichia coli
Caused by Controlled Expression of Toxins or Other Unrelated Proteins
Authors: Vázquez-Laslop Nora , Lee Hyunwoo , Neyfakh Alexander A.
Published: May 2006

Bacterial populations contain persisters, cells which survive exposure to bactericidal antibiotics and other lethal factors. Persisters do not have a genetic resistance mechanism, and their means to tolerate killing remain unknown. In exponentially growing populations of
Escherichia coli
the frequency of persister formation usually is 10
−7
to 10
−5
. It has been shown that cells overexpressing either of the toxic proteins HipA and RelE, both members of the bacterial toxin-antitoxin (TA) modules, have the ability to form more persisters, suggesting a specific role for these toxins in the mechanism of persistence. However, here we show that cells expressing proteins that are unrelated to TA modules but which become toxic when ectopically expressed, chaperone DnaJ and protein PmrC of
Salmonella enterica
, also form 100- to 1,000-fold more persisters. Thus, persistence is linked not only to toxicity caused by expression of HipA or dedicated toxins but also to expression of other unrelated proteins.
Transcriptome and Phenotypic Responses of
Vibrio cholerae
to Increased Cyclic di-GMP Level
Authors: Beyhan Sinem , Tischler Anna D. , Camilli Andrew , Yildiz Fitnat H.
Published: May 2006

Vibrio cholerae
, the causative agent of cholera, is a facultative human pathogen with intestinal and aquatic life cycles. The capacity of
V. cholerae
to recognize and respond to fluctuating parameters in its environment is critical to its survival. In many microorganisms, the second messenger, 3′,5′-cyclic diguanylic acid (c-di-GMP), is believed to be important for integrating environmental stimuli that affect cell physiology. Sequence analysis of the
V. cholerae
genome has revealed an abundance of genes encoding proteins with either GGDEF domains, EAL domains, or both, which are predicted to modulate cellular c-di-GMP concentrations. To elucidate the cellular processes controlled by c-di-GMP, whole-genome transcriptome responses of the El Tor and classical
V. cholerae
biotypes to increased c-di-GMP concentrations were determined. The results suggest that
V. cholerae
responds to an elevated level of c-di-GMP by increasing the transcription of the
vps
,
eps
, and
msh
genes and decreasing that of flagellar genes. The functions of other c-di-GMP-regulated genes in
V. cholerae
are yet to be identified.
The Ornibactin Biosynthesis and Transport Genes of
Burkholderia cenocepacia
Are Regulated by an Extracytoplasmic Function σ Factor Which Is a Part of the Fur Regulon
Authors: Agnoli Kirsty , Lowe Carolyn A. , Farmer Kate L. , Husnain Seyyed I. , Thomas Mark S.
Published: May 2006

Burkholderia cenocepacia
mutants that fail to produce the siderophore ornibactin were obtained following mutagenesis with mini-Tn
5
Tp. These mutants were shown to be growth restricted under conditions of iron depletion. In eight of the mutants, the transposon had integrated into one of two genes,
orbI
and
orbJ
, encoding nonribosomal peptide synthetases. In the other mutant, the transposon had inserted into an open reading frame,
orbS
, located upstream from
orbI
. The polypeptide product of
orbS
exhibits a high degree of similarity to the
Pseudomonas aeruginosa
extracytoplasmic function (ECF) σ factor PvdS but possesses an N-terminal extension of approximately 29 amino acids that is not present in PvdS. Three predicted OrbS-dependent promoters were identified within the ornibactin gene cluster, based on their similarity to PvdS-dependent promoters. The iron-regulated activity of these promoters was shown to require OrbS. Transcription of the
orbS
gene was found to be under the control of an iron-regulated σ
70
-dependent promoter. This promoter, but not the OrbS-dependent promoters, was shown to be a target for repression by the global regulator Fur. Our results demonstrate that production of ornibactin by
B. cenocepacia
in response to iron starvation requires transcription of an operon that is dependent on the Fur-regulated ECF σ factor gene
orbS
. A mechanism is also proposed for the biosynthesis of ornibactin.
Evidence that
Clostridium difficile
TcdC Is a Membrane-Associated Protein
Authors: Govind Revathi , Vediyappan Govindsamy , Rolfe Rial D. , Fralick Joe A.
Published: May 2006

Clostridium difficile
produces two toxins, A and B, which act together to cause pseudomembraneous colitis. The genes encoding these toxins,
tcdA
and
tcdB
, are part of the pathogenicity locus, which also includes
tcdC
, a putative negative regulator of the toxin genes. In this study, we demonstrate that TcdC is a membrane-associated protein in
C. difficile
.
Helicobacter pylori
Initiates the Stringent Response upon Nutrient and pH Downshift
Authors: Wells Derek H. , Gaynor Erin C.
Published: May 2006

Helicobacter pylori
was previously reported to lack a stringent response. In contrast, we show that after nutrient downshift,
H. pylori
produced abundant ppGpp and less total RNA. pH downshift also caused (p)ppGpp accumulation. Our observations indicate that nutrient deprivation and acid shock activate the stringent response in
H. pylori
.
CADMIUM SPECIES IN BASIC SOLUTION
Authors: Ryan D. E. , Dean J. R. , Cassidy R. M.
Published: May 2006

The principal cadmium-containing species in basic solutions varies with the concentration of hydroxide ion such that the solubility of cadmium hydroxide can be satisfactorily expressed, in solutions of high ionic strength, in terms of [Cd(OH)+] = 3.0 × 10−9[OH−]−1, [Cd(OH)2]soln = 1.0 × 10−6, [Cd(OH)3−] = 1.2 × 10−6[OH−], and [Cd(OH)42−] = 3.1 × 10−6[OH−]2. Since the solubility 10 varies from 10−4 to 10−6M, the predominant species at high concentrations of hydroxide ion is Cd(OH)42−; at low concentrations of hydroxide ion Cd(OH)+ is the principal cadmium-containing ion in solution. There is little free cadmium ion in solutions whose hydroxide ion concentration is greater than 10-4M.
THE Hg 6(3P1) PHOTOSENSITIZATION OF CHLORODIFLUOROMETHANE
Authors: Bellas M. G. , Strausz O. P. , Gunning H. E.
Published: May 2006

The reaction was studied in a circulatory apparatus under a variety of conditions. The sole primary process occurring is C—Cl bond scission. The Cl atoms formed in the primary step, through an abstractive attack on the substrate, generate chlorodifluoromethyl radicals (CF2Cl) All principal reaction products, CF2H2, CF2Cl2, CF2ClCF2Cl, CF2HCF2H, and CF2HCF2Cl, can be accounted for by the combination–disproportionation reactions of the CF2H• and CF2Cl• radicals. The observed strong dependence of the primary quantum yields on the incident light intensities has been ascribed to a rapid substrate-reforming step.
PROTON SPIN RELAXATION BY PARAMAGNETIC MOLECULAR OXYGEN
Authors: Mirhej M. E.
Published: May 2006

The proton spin–lattice relaxation time, T1, was measured for oxygen solutions of water, methanol, and acetone at different temperatures and resonance frequencies of 10.8, 20.0, and 29.8 Mc/s. The contribution of O2 to the relaxation was assumed to be due to the dipole–dipole and hyperfine interaction between the proton spins and the unpaired spins of the O2 molecule. The correlation times of the two interactions were related to the motion and the size of the polymeric cluster of the solvent. Activation energies for the two correlation times were obtained for the oxygen–water system from the dependence of the relaxation time on the resonance frequency. No separation of the two terms was possible for either the oxygen–methanol or oxygen–acetone systems because of their independence of magnetic field variations. The correlation time of the hyperfine term was postulated to be a measure of the extent of solvent–oxygen hydrogen bond strength in all the measured systems.
ISOPIMARIC ACID
Authors: Antkowiak W. , Edwards O. E. , Howe R. , ApSimon J. W.
Published: May 2006

Evidence is presented for the epimeric character of the C-13 substituents in pimaric and isopimaric acids and for the nuclear double bond location in isopimaric acid. This work, coupled with recent synthetic work and rotatory dispersion evidence, permits assignment of the structure and stereochemistry IV to isopimaric acid. Hydroboration and selenium dioxide oxidation of the acid are described.
REACTION OF DIHYDROPYRAN WITH ETHYL AZIDOFORMATE
Authors: Brown I. , Edwards O. E.
Published: May 2006

Photochemical reaction of ethyl azidoformate with dihydropyran gave a good yield of the very reactive aziridine III. The thermal reaction between the two compounds took a completely different course, via triazoline XI to 2-hydroxy-2-ethoxycarbonamidotetrahydropyran XIII.
LABELLING OF NUCLEOSIDES WITH TRITIUM
Authors: LePage G. A. , Junga Irene G.
Published: May 2006

The synthesis of 9-(α,β-D-2′-deoxyribofuranosyl)-2-amino-6-mercaptopurine with tritium labelling in both base and sugar was attempted. At the step where a mercury salt of the base and the blocked chlorosugar were coupled in benzene, the tritium labelling was lost, apparently by an exchange with the protons of the solvent. This appeared to be catalyzed by the mercuric chloride. It was demonstrated that unlabelled nucleoside could be tritium labelled by refluxing it in benzene-T or toluene-T with mercuric chloride. By this exchange process, both base and sugar were tritiated, but a larger amount of tritium appeared in the base. Because of the availability of benzene-T and toluene-T of high specific radioactivity, this appears to be a practical means of synthesis of the labelled nucleoside. This exchange reaction may be useful for the study of carbon–hydrogen bond stabilities.
THE PREPARATION OF 3-ALKYLTHIOINDOLES
Authors: Jardine R. V. , Brown R. K.
Published: May 2006

3-Ethylthioindole has been prepared by Fischer cyclization of the condensation product of phenylhydrazine and ethylthioacetaldehyde diethyl acetal, and also by a route involving the reaction of ethyl iodide with the sodium borohydride reduction product of 1,2-dithiolo[4,3-b]indole-3-(4H)-thione. The last-named compound was obtained by reaction of 2-carbethoxy-indoxyl with phosphorus pentasulfide.
SYNTHESIS OF 8-AZA-D-HOMO-18-NORESTRONE METHYL ETHER
Authors: Nelson Norman A. , Tamura Yasumitsu
Published: May 2006

Alkylation of the potassium salt of 1,4-dihydro-2,6-dimethoxybenzene with 2-(2-bromoethyl)piperidine yielded the bis-enol ether I, which, on acid hydrolysis, afforded the crystalline vinylogous amide II. Lithium aluminium hydride reduction of II gave two isomers of 1,2,3,4,4a,5,6,6a,8,9,10,10a-dodecahydro-7H-benzo[c]quinolizin-7-one (III). A similar series of reactions starting with 1-(2-chloroethyl)-6-methoxy-1,2,3,4-tetrahydroisoquinoline hydrochloride (V) gave two isomers of 2,3,4,4a, 6,7,11b,12,13,13a-decahydro-9-methoxy-1H-di-benzo[a,f]quinolizin-1-one (8-aza-D-homo-18-norestrone methyl ether) (IX).
THE Hg 6(3P1) PHOTOSENSITIZED DECOMPOSITION OF CYCLOHEXENE VAPOR
Authors: Maré G. R. De , Strausz O. P. , Gunning H. E.
Published: May 2006

The reaction follows the pattern established for the triplet state reactions of olefins in general. The major products, ethylene, 1,3-butadiene, vinylcyclobutane, cyclohexane, various C12-compounds, and polymer, can best be accounted for by the allylic C—H and C—C bond cleavage of the primary triplet biradicals and the ring closure and fragmentation reactions of the resulting open chain biradicals. At least three types of triplet state species must be involved in the mechanism. The rate equations, developed on the assumed mechanism, satisfactorily describe the observed product distribution and kinetic features of the system and permit the estimation of the elementary rate constant values and the lifetimes of the various transient biradicals involved. Preliminary experiments with cycloheptene indicate that vinylcyclopentane is an important product.
TERPENOIDS: VIII. THE IMMEDIATE PRECURSORS OF HELMINTHOSPORAL AND HELMINTHOSPOROL
Authors: Mayo P. De , Williams R. E. , Spencer E. Y.
Published: May 2006

An earlier investigation had shown that helminthosporal, the toxin isolated from growths of Helminthosporium sativum, does not exist as such in the culture, but is formed from a precursor on subsequent mild treatment with acid, base, or heat. What is believed to be the immediate precursor of helminthosporal has now been isolated, as the acetal (IV), from an aged fungus extract. The corresponding precursor of helminthosporal, also as the acetal (V), accompanied it. Hydrolysis of the latter gave prehelminthosporol (also isolated from fresh extracts), which was converted into helminthosporol. Hydrolysis of the acetal of prehelminthosporal gave helminthosporal directly.Although prehelminthosporol exists in the fresh extracts, it appears that more exists, together with prehelminthosporal, in the form of unstable complexes, possibly dimeric hemiacetals, which break down under very mild conditions. One of these has been obtained in moderately pure condition.
SOME TRANSFORMATIONS OF TETRACYCLINE AT THE 4-POSITION
Authors: Blackwood Robert K. , Stephens Charles R.
Published: May 2006

Reactions leading to the replacement of the 4-dimethylamino group of tetracycline by keto, hydroxy, hydroxyimino, hydrozono, and amino groups are reported.
PYRAZOLINES: IV. REARRANGEMENT OF ALKYL GROUPS DURING THE PYROLYSIS OF 4,4-DIALKYL-3-CYANO-3-CARBOMETHOXY-Δ1-PYRAZOLINES
Authors: McGreer Donald E. , McDaniel Robert S. , Vinje Magnus G.
Published: May 2006

A number of 4,4-dialkyl-3-cyano-3-carbomethoxy-Δ1-pyrazolines have been synthesized. Pyrolysis of these pyrazolines yielded cyclopropane and olefin products. The formation of olefin products by rearrangement of an alkyl group from C4 to C5 of the pyrazoline system suggests that positive charge is developed on C5 in the transition state. Ionic character in the transition state was also indicated by the fact that the rate of pyrolysis is faster in polar than in nonpolar solvents.
PYRAZOLINES: V. RING CLOSURE TO OXYGEN IN THE PYROLYSIS OF 3-ACETYL-Δ1-PYRAZOLINES
Authors: McGreer Donald E. , Chiu Norman W. K. , Vinje Magnus G.
Published: May 2006

The pyrolysis of 3-methyl-3-acetyl-Δ1-pyrazoline (IV) and cis- and trans-3,5-dimethyl-3-acetyl-Δ1-pyrazoline (V and VI) has been studied. Pyrolysis of IV gave 2,3-dimethyl-4,5-dihydrofuran (XI) as a minor product, indicating some ring closure to oxygen in these reactions. Pyrolysis of V gave 2,3,5-trimethyl-4,5-dihydrofuran (XVII) as 23% of the product, whereas VI yielded only a trace of XVII. This fact and other differences in the product analysis from isomers V and VI are discussed in terms of the possible mechanism for the pyrolysis reaction.
EFFECT OF ELECTROLYTE ENVIRONMENT ON DIVALENT TARTRATE ION MOBILITY
Authors: Nichol James C. , Heikkinen Duane G. , Glass Gary E.
Published: May 2006

The variation of the electrophoretic mobility, uT, of divalent tartrate ion with changing electrolyte environment has been studied. Mobilities were determined from boundary velocity measurements at 1.00 °C in the Tiselius electrophoresis apparatus. The solutions used, which were adjusted to pH 8.3–8.5, were principally either 0.04667 M C2T or 0.01 M C2T–0.11 M CA, where C+, T=, and A− are, respectively, a univalent cation, divalent tartrate ion, and a univalent anion. Relative viscosities, ηrcl, of a number of these solutions were also obtained. For a given anion environment, the variation of uT with changing cation is characterized by a minimum at sodium and a maximum at tetramethylammonium for a series of six alkali metal and tetraalkylammonium ions. For the alkali metal cations and for tetrapropylammonium ion, uT undergoes a distinct decrease when the solution is changed from 0.04667 M C2T to 0.01 M C2T–0.11 M CCl. For all solutions containing an anion A−, uT decreases with increasing hydrocarbon content of A− for a given cation. Possible ion association, obstruction, and ion–solvent interaction effects are considered.
THE METHYLATION OF THE RESORCINOLATE DIANION: II. PER-METHYLATED RESORCINOL: 2,2,4,6,6-PENTAMETHYLCYCLOHEX-4-EN-1,3-DIONE
Authors: Stein Allan R.
Published: May 2006

Structural evidence for the enedione products, 2,2,4,6,6-pentamethylcyclohex-4-en-1,3-dione and 2,2,6,6-tetramethylcyclohex-4-en-1,3-dione, which are the principal products from the methyl iodide alkylation of the dilithium resorcinol salt in nonpolar aprotic or very polar hydroxylic solvents, is presented. The diimide and lithium aluminium hydride reduction products are presented and, together with the decarboxylated hydrolysis product, 2,4,6-trimethylcyclohex-2-en-5-one, constitute proof of the structure of the 2,2,4,6,6-pentamethyl-cyclohex-4-en-1,3-dione. Some of the synthesis potential of resorcinolate alkylations is indicated.
THE CONVERSION OF META- AND PARA-SUBSTITUTED BENZALDOXIME ARENESULFONATES TO NITRILES
Authors: Crawford Robert J. , Woo Charles
Published: May 2006

The meta- and para-substituted syn-benzaldoxime arenesulfonates were prepared from the reaction between the sodium salt of the oxime and the acid chloride in absolute ether. These oxime esters reacted in aqueous alcohol readily to yield the corresponding nitriles exclusively. The reaction rates can be correlated by a Hammett plot with a slope of −0.77. Several para-substituents tended to deviate from the line. Isotope study gives a kH/kD ratio of 4.51. The rate was found to be sensitive to the change in the ionizing power of the solvent, and to the change in the strength of the esterifying acid. The addition of lithium perchlorate gives rise to a normal salt effect. Sodium acetate brings about a basic elimination having a Hammett p value of + 0.44. A mechanism is proposed in the light of these results.
SOME ASPECTS OF THE CHEMISTRY OF CATHARANTHINE AND CLEAVAMINE
Authors: Kutney James P. , Brown Richard T. , Piers Edward
Published: May 2006

Chemical and spectroscopic evidence is presented for an interesting acid-catalyzed rearrangement of the alkaloid catharanthine. Four reaction products (descarbomethoxycatharanthine and cleavamine and its two dihydro derivatives) were isolated, and their formation is rationalized by a mechanism involving ring-opened intermediates. Evidence is presented in support of the proposed mechanism and, in particular, a novel transannular cyclization leading to the Iboga alkaloid skeleton is shown in support of the steps postulated for the formation of descarbomethoxycatharanthine.The X-ray analysis of cleavamine methiodide established the absolute configuration of the lone asymmetric center present in the molecule and, from these results, the absolute configuration of the Iboga alkaloids can be derived.
ISOBENZOFURANE, A TRANSIENT INTERMEDIATE
Authors: Fieser Louis F. , Haddadin Makhluf J.
Published: May 2006

A study of Diels–Alder reactions of tetraphenylcyclopentadienone (II) coupled with development of two improved procedures for the generation of benzyne, one of which affords a practical route to the reactive dienophile 1,4-dihydronaphthalene-1,4-endo-oxide (Ia), led to an investigation of the reaction of Ia and II. At 80° these reactants combine readily to give the adduct IIIa, which is cleaved on pyrolysis to isobenzofurane VIIIa and 1,2,3,4-tetraphenylbenzene (IX). The transient existence of isobenzofurane (VIIIa) was established by trapping it with the 1,4-endo-oxide Ia and isolation of the adducts X and XI. In confirmation of the interpretation, X and XI were obtained by independent synthesis from the adduct Va from Ia and α-pyrone and thermal decomposition of Va in the presence of Ia as trapping agent. Parallel experiments with 1,4-dimethyl-1,4-dihydronaphthalene-1,4-endo-oxide, as well as mixed additions, supported the interpretations advanced. Evidence is presented to show that isobenzofurane (VIIIa) invariably adds exo to the bicyclic dienophile.
CHEMISTRY OF NYBOMYCIN: II. SYNTHESIS OF 4,5-DIMETHYL-2,7-DIOXO-1,2,7,8-TETRAHYDRO-1,8-DIAZAANTHRACENE
Authors: Leadbetter Graham , Rinehart Jr. Kenneth L.
Published: May 2006

4,5-Dimethyl-2,7-dioxo-1,2,7,8-tetrahydro-1,8-diazaanthracene, a compound previously obtained from phosphorus – hydrogen iodide reduction of deoxynybomycin, has been synthesized in eight steps from m-xylene, in 5% overall yield.
POLYOXYPHENOLS OF WESTERN RED CEDAR (THUJA PLICATA DONN): III. STRUCTURE OF PLICATIC ACID
Authors: Gardner J. A. F. , Swan E. P. , Sutherland S. A. , MacLean Harold
Published: May 2006

Periodate oxidation studies, nuclear magnetic resonance spectra of derivatives, and X-ray crystallographic data have shown that plicatic acid, the major component of the heartwood extractive of western red cedar (Thujaplicata Donn), is 2,3,6-trihydroxy-7-methoxy-2-hydroxymethyl-4-(3′,4′-dihydroxy-5′-methoxyphenyl)-tetralin-3-carboxylic acid. The asymmetric configuration by X-ray data is 2R,3S,4R or its enantiomer, by Cahn–Ingold nomenclature.
ÉTUDE QUANTITATIVE DES RÉACTIONS D'OZONOLYSE: I. OZONATION DU TÉTRAPHÉNYLÉTHYLÈNE
Authors: Fliszár S. , Gravel D. , Cavalieri E.
Published: May 2006

not available
SELECTIVE NUCLEOPHILIC SUBSTITUTION AND PREFERENTIAL EPOXIDE FORMATION
Authors: Dick A. J. , Jones J. K. N.
Published: May 2006

The tri-O-methanesulfonyl derivatives of methyl β-D-xylopyranoside, methyl β-L-arabinopyranoside, and methyl α-L-arabinopyranoside undergo selective substitution at C-4, when heated with sodium azide in N,N-dimethylformamide, to yield 4-azido derivatives with inversion of configuration at C-4. The resultant 4-azido-2,3-di-O-methanesulfonyl derivatives were converted, by reaction with sodium methoxide, into 2,3-anhydro compounds whose configurations were assigned by nuclear magnetic resonance analysis. The mechanism of epoxide formation is discussed.
POLAROGRAPHY OF 7-BENZONORBORNENONES
Authors: Tanida Hiroshi , Miyazaki Hiroshi , Ishitobi Hiroyuki
Published: May 2006

not available
SUR LES SPECTRES INFRAROUGES DES PHTALOCYANINES
Authors: Shurvell H. F. , Pinzuti L.
Published: May 2006

Infrared spectra of metal-free phthalocyanine, chlorinated and unchlorinated copper phthalocyanines, and three new metal derivatives of phthalocyanine: MoPc, Na2Pc, and AlOH—Pc (Pc = C32H16N8), have been recorded. Assignments have been suggested for many of the peaks in the infrared spectra of the phthalocyanines.