bluuebunny/crossref_metadata_2025 huggingface dataset:
99mTc-HMPAO as a Tracer of Cerebral Blood Flow in Newborn Infants
Authors: Børch Klaus , Greisen Gorm
Published: September 2004

Studies on the kinetics of 99mTc-D,L-hexamethylpropylene amine oxime (99mTc-HMPAO) in adults have shown that it is not an ideal tracer of CBF because it underestimates high-flow areas. Knowledge of the kinetics of the tracer is important in evaluating the studies. The kinetics of 99mTc-HMPAO in infants may be different from that in adults, therefore, we examined the cerebral uptake and retention of 99mTc-HMPAO in neonates and estimated the degree of brain-to-blood back diffusion by comparing corresponding 133Xe flow images and 99mTc-HMPAO distribution images. In addition, we measured the urinary excretion of 99mTc-HMPAO. Regional CBF was measured using a mobile brain dedicated, fast-rotating, four-head multidetector system specially designed for neonatal studies. Tracers were 99mTc-HMPAO (4 MBq/kg) and 133Xe (500 MBq/kg). Cerebral uptake and leak-out of 99mTc-HMPAO were measured by a single scintillation crystal placed over the frontoparietal part of the infant's head. The cerebral retention of 99mTc-HMPAO was analyzed in 50 infants. The mean gestational age and birth weight (95% confidence interval) were 34.4 weeks (32.2–35.7) and 2,326 g (1,954–2,995), respectively. The cerebral uptake of 99mTc-HMPAO was examined in 16 of the 50 infants, and activity during 24 h was monitored in five. In 11 infants, corresponding 133Xe studies were performed. Urinary excretion was studied in 12 infants. The maximal activity in the brain was reached 90s after i.v. injection and was 104% (98–111) of the stable level, which was reached approximately 3 min after the injection. The decay corrected leakout of the tracer during the following 24 h was 1.0% (0.4–1.5) per hour. The cerebral retention was calculated at 6.8% (6.1–7.6), highest in the group of ictal studies and lowest in premature infants with intracranial hemorrhage. The mean value of the fixation/clearance ratio α was estimated at 3.4 (2.8–4.4). The mean urinary excretion over 24 h was 19.5% (11.4–27.7) and was significantly related to renal function as indicated by serum urea (p = 0.02 r2 = 0.55). A four-compartment model describing the kinetics of 99mTc-HMPAO is shown to be valid in neonates. The cerebral retention of the tracer is higher in neonates because of higher extraction and lower initial back diffusion from brain to blood. In linearizing 99mTc-HMPAO distribution images, a smaller correction is necessary, and we propose a value of the correction factor of 3.4. In this way, 99mTc-HMPAO is a more reliable tracer of the distribution of CBF in neonates compared with adults. The urinary excretion is significantly reduced compared with adults, and the radiation dose to the bladder wall is reduced. The effective dose is 0.3 mSv/MBq/kg.
Results of the Bone‐Anchored Hearing Aid in Unilateral Hearing Loss
Authors: Wazen Jack J. , Spitzer Jaclyn , Ghossaini Soha N. , Kacker Ashutrosh , Zschommler Anne
Published: September 2004

Objectives The advantages of binaural hearing are well established and universally accepted. However, a tendency remains to withhold the benefits of binaural hearing to adults and children with one normal ear. The purpose of this study is to demonstrate the benefit of the bone‐anchored hearing aid (BAHA) in a group of patients with unilateral conductive or mixed hearing loss.

Study Design This is a prospective study of nine patients (five males and four female patients) with conductive or mixed hearing loss who met the criteria for BAHA except for having normal hearing in the other ear. They had congenital aural atresia or mastoidectomies secondary to chronic ear infections with or without cholesteatoma or had a temporal bone tumor excised

Methods Patients had evaluations before and after implantation, including audiological testing and responses to a standardized hearing handicap questionnaire. Statistical analyses of the data were made using the Wilcoxon signed rank test and the paired Student t test for repeated measures.

Results All patients had tonal and spondee threshold improvement with BAHA when compared with thresholds before treatment. Speech recognition performance in BAHA‐aided conditions was comparable to the patient's best score in unaided condition. Patients reported a significant improvement in their hearing handicap scores with the BAHA.

Conclusions The use of BAHA has significantly improved the hearing handicap scores in patients with unilateral conductive or mixed hearing loss. The proven safety and efficacy of the device promote its use in unilateral cases that traditionally had been left unaided.
Endoscopic Extraction of an Intranasal Tooth: A Review of 13 Cases
Authors: Lee Fei‐Peng
Published: September 2004

Objective To present the clinical experience of a series of 13 consecutive cases of an intranasal tooth treated by endoscopic extraction during a 15‐year period.

Study Design Retrospective review.

Methods The records of 13 patients who underwent endoscopic extraction of an intranasal tooth at Taipei Medical University Hospital and Chang Gung Memorial Hospital between 1986 and 2000 were reviewed.

Results All the patients had an uneventful recovery and the presenting symptoms were completely relieved after surgery. The follow‐up period was 6 months to 14 years 5 months (average, 9 yr 2 mo). Examination of these extracted teeth showed that 11 were supernumerary teeth and two were ectopic permanent canine teeth.

Conclusions Endoscopic extraction of the intranasal tooth has the advantages of good illumination, clear visualization, and precise dissection, and in our experience the result of endoscopic extraction of an intranasal tooth is satisfactory. We recommend the routine use of a rigid endoscope in the treatment of an intranasal tooth.
Significance of Retropharyngeal Node Dissection at Radical Surgery for Carcinoma of the Hypopharynx and Cervical Esophagus
Authors: Amatsu Mutsuo , Mohri Mitsuhiro , Kinishi Minoru
Published: September 2004

Objectives To clarify the efficacy of dissection of retropharyngeal lymph nodes (RPLNs) in the surgical treatment of carcinoma of the hypopharynx and cervical esophagus.

Study Design We started planned dissection of the RPLN during initial radical surgery in patients with squamous cell carcinoma of the hypopharynx or the cervical esophagus in 1988. Until 1997, we performed this procedure as a standard operation in 82 consecutive patients.

Methods Mortality resulting from RPLN metastasis was compared between 82 patients who underwent RPLN dissection and 69 patients who did not undergo the procedure.

Results Of 82 patients, 16 patients (20%) had positive RPLNs. These patients were at high risk of recurrence unless the node(s) were dissected. Although RPLN dissection did not improve the cumulative 5‐year survival rate, it significantly decreased the number of patients who died of RPLN metastasis (χ2 = 3.68, P <.1). Four of the 16 patients who had positive RPLNs survived without any recurrence.

Conclusion Bilateral dissection of the RPLN during initial surgery is highly recommended in every surgical case of carcinoma of the hypopharynx and cervical esophagus.
Effect of 3M™ Coban™ Self-Adherent Wraps on Edema and Function of the Burned Hand: A Case Study
Authors: Lowell M. , Pirc P. , Ward R. S. , Lundy C. , Wilhelm D. A. , Reddy R. , Held B. , Bernard J.
Published: September 2004

Edema and limited function are common acute problems associated with hand burns. This case study examined the effects of 3M™ Coban™ Self-Adherent Wraps on edema and function in a 59-year-old male (46% TBSA flame injury) with newly skin grafted dorsally burned hands. At the time of each dressing change, circumferential measurements were taken of both hands and weekly active range of motion and grip strength measurements were recorded. The nine-hole peg test was used to appraise dexterity. During the 4-week study period, there was less edema, greater active range of motion and grip strength, and greater dexterity in the hand with 3M™ Coban™ Self-Adherent Wraps as compared with the control hand. This case study suggests that 3M™ Coban™ Self-Adherent Wraps were effective in reducing edema in the skin-grafted hand after skin grafting. It further appeared that the reduced edema may have contributed to improved hand function and that 3M™ Coban™ Self-Adherent Wraps as a compressive dressing do not impede hand function.
Use of Speech Pathology Services in the Burn Unit
Authors: Snyder C. , Ubben P.
Published: September 2004

Speech-language pathologists (SLPs) provide intervention for communication challenges and swallowing disorders (dysphagia) that are common in cases of severe burns because of ventilator use, prolonged or multiple intubations, and tracheostomy tubes. To identify current inclusion of SLP services in burn care management, a survey was sent to 139 burn units across the United States. Results revealed limited inclusion of SLPs in burn care despite pertinent areas of SLP expertise. Education of burn care teams on the benefits of SLP inclusion is needed. Potential benefits in pain and medical management reducing length of hospitalization and increasing cost-effective care by inclusion of SLPs in burn care management warrants further research.
An Unusual Cause of Burn Injury: Fig Leaf Decoction Used as a Remedy for a Dermatitis of Unknown Etiology
Authors: Özdamar Erkut , Özbek Serhat , Akin Selçuk
Published: September 2004

Medicinal plant extracts are commonly used worldwide. Their use relies mostly on historical and anecdotal evidence and might be so hazardous. Phytophotodermatitis is a well-known entity that is caused by the sequential exposure to certain species of plants containing furocoumarins and then to sunlight. In this article, superficial burn lesions caused by fig leaf decoction that was applied to a patient's both upper extremity as a remedy for a dermatitis of unknown etiology is reported. Direct sun exposure is an essential component of phytophotodermatitis. All reported cases to date have in common that patients are exposed to direct sunlight or to artificial UVA lights (like solarium) of varying durations. In our case neither direct sun exposure, other than inevitable indoor UVA influence, nor blister formation was present. The etiologic factors, symptoms, signs, course, and treatment alternatives for phytophotodermatitis are also reviewed briefly.
Serial Measurements Increase the Accuracy of Laser Doppler Assessment of Burn Wounds
Authors: Mileski W. J. , Atiles L. , Purdue G. , Kagan R. , Saffle J. R. , Herndon D. N. , Heimbach D. , Luterman A. , Yurt R. , Goodwin C. , Hunt J. L.
Published: September 2004

Traditional methods of judging burn depth by clinical evaluation of the wound based on appearance and sensation remain in wide use but are subject to individual variation by examiner. In addition to the clinical difficulties with burn wound management, observer dependency of wound assessment complicates clinical trials of burn wound therapy. A laser Doppler flowmeter with a multichannel probe was used to measure burn wound perfusion as a tool to predict wound outcome. Serial measurement with laser Doppler flowmetry had an 88% specificity and a positive predictive value of 81% for identifying nonhealing wounds. These results suggest that laser Doppler flowmetry is a potentially useful tool for burn wound assessment.
Occupational Lesion of the Suprascapular Nerve Leading to Marked Atrophy of the Supra- and Infraspinatus Muscles
Authors: Araujo Mauro Gomes , Fragoso Yara Dadalti
Published: September 2004

Suprascapular neuropathy is a relatively uncommon cause of shoulder pain and it is usually related to nerve entrapment. Marked atrophy of the supra- and infraspinatus muscles is not often observed, because the pain and limitation of movements could require medical attention at early stages of the disease. We report on a case of suprascapular neuropathy in a young male resulting from occupational compression of the nerve. A picture of the patient is included.
In vivo investigation of the transcription, processing, endonucleolytic activity, and functional relevance of the spatial distribution of a plant miRNA
Authors: Parizotto Eneida Abreu , Dunoyer Patrice , Rahm Nadia , Himber Christophe , Voinnet Olivier
Published: September 2004

We show, with miR171, that plant miRNA genes are modular independent transcription units in which the fold-back pre-miRNA is sufficient for miRNA processing, and that the upstream region contains highly specific promoter elements. Processing depends on flanking sequences within the miRNA stem-loop precursor rather than the miRNA sequence itself, and mutations affecting target pairing at the center and 5′ but not 3′ region of the miRNA compromise its function in vivo. Inactivation of the SDE1 RNA-dependent-RNA-polymerase was mandatory for accurate representation of miRNA activity by sensor constructs in Arabidopsis. Work in sde1 background revealed a near-perfect spatial overlap between the patterns of miR171 transcription and activity, supporting the idea that plant miRNAs enable cell differentiation.
A Putative Polyketide Synthase/Peptide Synthetase fromMagnaporthe griseaSignals Pathogen Attack to Resistant Rice[W]
Authors: Böhnert Heidi U. , Fudal Isabelle , Dioh Waly , Tharreau Didier , Notteghem Jean-Loup , Lebrun Marc-Henri
Published: September 2004

Isolates of the rice blast fungus Magnaporthe grisea that carry the gene encoding Avirulence Conferring Enzyme1 (ACE1) are specifically recognized by rice (Oryza sativa) cultivars carrying the resistance gene Pi33. This recognition enables resistant plants to activate a defense response. ACE1 was isolated by map-based cloning and encodes a putative hybrid between a polyketide synthase and a nonribosomal peptide synthetase, enzymes involved in microbial secondary metabolism. ACE1 is expressed exclusively during fungal penetration of host leaves, the time point at which plant defense reactions are triggered. Ace1 appears to be localized in the cytoplasm of the appressorium. Mutation of the putative catalytic site of the β-ketoacyl synthase domain of Ace1 abolishes recognition of the fungus by resistant rice. This suggests that Ace1 biosynthetic activity is required for avirulence. Our results are consistent with the hypothesis that the fungal signal recognized by resistant rice plants is the secondary metabolite whose synthesis depends on Ace1.
An in‐vitro investigation of the antibacterial effect of nisin in root canals and canal wall radicular dentine
Authors: Turner S. R. , Love R. M. , Lyons K. M.
Published: September 2004

Aim  To determine whether nisin, a bacteriocin, would be effective at killing Enterococcus faecalis and Streptococcus gordonii cells in solution and within the root canal system.

Methodology  Bacterial isolates of E. faecalis and S. gordonii were grown from glycerol stocks in closed tubes containing BHY broth at 37 °C. The minimum bactericidal concentration (MBC) of nisin for both bacterial species was determined by a microdilution method. Extracted human teeth were decoronated to produce roots of equal length with a single canal and divided into six groups of 10 roots. The canals were prepared to a master apical size 30 file using 0.04 taper Ni‐Ti rotary instruments. Bacterial samples of each species were inoculated into three groups of prepared roots and incubated in closed tubes at 37 °C for 21 days. The root canals in each group were then medicated with water (control), calcium hydroxide powder mixed with sterile water [Ca(OH)2], or nisin and incubated for a further 7 days. Rotary Ni‐Ti files were used to take radicular dentine samples from the walls of each canal which were then incubated in BHY broth for 24 h. Optical density (OD600) readings were taken as a measure of bacterial growth.

Results  The MBC of nisin for E. faecalis and S. gordonii was 70 and 20 mg mL−1 respectively. Calcium hydroxide and nisin medication eradicated infection within the root canal while cells remained viable in the control group. Mean optical density (OD600) readings from canal wall dentine shavings infected with E. faecalis were 1.32 ± 0.98, 0.73 ± 0.27 and 0.69 ± 0.38 for the control, Ca(OH)2 and nisin samples respectively. Corresponding mean readings for S. gordonii were 1.19 ± 0.18, 0.73 ± 0.15 and 0.60 ± 0.29. The Ca(OH)2 and nisin group readings were significantly (P < 0.01) lower than the control for each species as tested by Student's t‐test and Mann–Whitney U statistical analysis. Values for Ca(OH)2 and nisin were not significantly (P > 0.01) different.

Conclusion  Nisin was effective at eradicating E. faecalis and S. gordonii cells in pure culture and was comparable with Ca(OH)2 in the elimination of these species from within the root canal system.
A one step procedure for luting glass fibre posts: an SEM evaluation
Authors: Grandini S. , Sapio S. , Goracci C. , Monticelli F. , Ferrari M.
Published: September 2004

Aim  To evaluate the ability of two luting procedures for bonding translucent fibre posts to form resin tags, adhesive lateral branches, and resin dentine interdiffusion zones (RDIZ).

Methodology  Forty root filled teeth, extracted for periodontal reasons, were selected for the study. The teeth were randomly divided into four groups of 10 each. Group 1: One Step, light‐cured (LC) 20 s + dual link resin cement (LC 20 s); group 2: One Step, not light‐cured (NLC) + dual link resin cement (LC 30 s); group 3: One Step (NLC) + dual link resin cement (LC 60 s); group 4: One Step (NLC) + dual link resin cement (LC 90 sec). Forty translucent fibre posts (DT posts, RTD) were inserted. Then, root specimens were processed for scanning electron microscope (SEM) observations to assess the continuity of the RDIZ, the presence or absence of gaps and the density and morphology of resin tags using a four‐step scale method.

Results  With all luting procedures the formation of a RDIZ occurred. However, the microscopic examination of adhesive interfaces revealed that the percentage of RDIZ was significantly higher in group 1 than in the other three groups (P < 0.05). Group 4 had a higher percentage of RDIZ than group 3, which in turn exhibited a greater percentage than group 2, but these differences were not statistically significant (P > 0.05). Resin tag formation was evident in all the groups. The characteristic reverse cone shape of resin tags was always noted in the coronal and middle third of all groups, and in the apical third of group 1. In the apical third a shorter length and a less uniform appearance of resin tags were noted in groups 2, 3 and 4.

Conclusions  In this laboratory study, when bonding a translucent fibre post into a root canal, the luting procedure including light curing of the adhesive solution before the placement of the cement was more satisfactory, from a SEM standpoint, than the procedure involving the simultaneous curing of adhesive and cement (one step procedure).
Comparison of long‐term papilla healing following sulcular full thickness flap and papilla base flap in endodontic surgery
Authors: Velvart P. , Ebner‐Zimmermann U. , Ebner J. P.
Published: September 2004

Aim  To compare long‐term loss of papilla height when using either the papilla base incision (PBI) or the standard papilla mobilization incision in marginal full thickness flap procedures in cases with no evidence of marginal periodontitis.

Methodology  Twelve healthy patients, free of periodontal disease, who had intact interdental papillae were referred for surgical treatment of persisting apical periodontitis and included in the study. The flap design consisted of two releasing incisions connected by a horizontal incision. The marginal incision involved the complete mobilization of the entire papilla in one interproximal space but in the other interproximal space the PBI was performed. Further apically a full thickness flap was raised. Following flap retraction, standard apical root‐end resection and root‐end filling was performed. Flap closure was achieved with microsurgical sutures. The PBI was sutured with two to three interrupted sutures (size 7/0), the elevated papilla was reapproximated with vertical mattress sutures (size 7/0), which were removed 3–5 days after the surgery. The height of the interdental papilla was evaluated preoperatively and postoperatively after 1‐, 3‐ and 12‐month recall using plaster replicas. The loss of papilla height was measured using a laser scanner. Papilla paired sites were evaluated and statistically analysed.

Results  Most papilla recession took place within the first month after the surgery in the complete elevation of the papilla. Further small increase in loss of papilla height resulted at 3 months. After 1 year the loss of height diminished to 0.98 ± 0.75 mm, but there was no statistical difference between the various recall intervals. In contrast, after PBI only minor changes could be detected at all times. There was a highly significant difference between the two incision techniques for all recall appointments (P < 0.001).

Conclusions  In the short as well as long‐term the PBI allows predictable recession‐free healing of the interdental papilla. In contrast, complete mobilization of the papilla displayed a marked loss of the papilla height in the initial healing phase although this was less evident 1 year postoperatively. In aesthetically relevant areas the use of the PBI is recommended, to avoid opening of the interproximal space, when periradicular surgical treatment is necessary.
Endodontic treatment of an invaginated maxillary lateral incisor with a periradicular lesion and a healthy pulp
Authors: Tsurumachi T.
Published: September 2004

Aim  To report the healing of a periradicular lesion following nonsurgical root canal treatment of a dental invagination.

Summary  A case of dens invaginatus type 3 with a periradicular lesion and a healthy pulp is reported. Nonsurgical root canal treatment of the invagination was performed successfully and resolved an associated periradicular lesion. Despite the complex anatomy and a diagnosis of apical periodontitis, pulp health was retained after endodontic treatment of the invaginated canal. Clinical considerations and treatment are discussed and reported.

Key learning points

Dens invaginatus can present in a variety of forms, knowledge of which can usefully inform endodontic diagnosis and treatment.

In certain cases, success can be achieved by treating the invagination alone.

Pulp health may be preserved during and after treatment of an infected invagination.
Protocolized weaning from mechanical ventilation: ICU physicians’ views
Authors: Blackwood Bronagh , Wilson‐Barnett Jenifer , Trinder John
Published: September 2004

Background.  The use of protocols during weaning from mechanical ventilation is uncommon in the UK, despite research pointing to their potential benefits. This may be because the research evidence is considered not to apply in different settings. Intensive care unit consultant physicians are the major decision‐makers in weaning in the UK and any attempt to introduce protocolized weaning will require consideration of their views.

Aim.  The aim of this paper is to report a study exploring intensive care physicians’ views on (i) weaning from mechanical ventilation, (ii) the utility of weaning protocols and (iii) nurses’ roles in the weaning process. A specific goal was to identify potential aids and barriers to developing weaning protocols and their introduction into clinical practice.

Methods.  Qualitative interviews were conducted with a purposive sample of 10 consultant physicians in two intensive care units in Northern Ireland and subjected to content analysis.

Findings.  The primary themes identified were (i) information required for weaning decisions and clinical judgement, (ii) professional boundaries, (iii) protocol issues and (iv) timing of weaning. Three types of information were deemed to be required for weaning decisions – empirical objective, empirical subjective and abstract – and interviewees considered that it would be challenging to incorporate all into a protocol. They were divided on whether protocols were useful when nursing experience was limited. Some groups of patients were thought more suitable than others for protocolized weaning.

Conclusions.  Although local physicians were supportive in theory, introduction of protocolized weaning is likely to be difficult because of the breadth of information required for successful decision‐making. Consultant views in this study were not consistent with American findings that physicians’ caution may unnecessarily prolong weaning.
Meeting the needs of minority ethnic patients
Authors: Cortis Joseph D.
Published: September 2004

Background.  Certain aspects of nursing care related to minority ethnic patients are being highlighted in the literature, but there is little exploration of nurses’ experiences of caring for people from specific minority ethnic groups.

Aim.  This paper reports an investigation into the experiences of Registered Nurses caring for hospitalized Pakistani patients in the United Kingdom.

Method.  A qualitative study, with a sample of 30 Registered Nurses using semi‐structured interviews. The sample was self‐selecting from a large health care organization in the north of England, covering adult acute, critical and rehabilitation care settings.

Results.  Interviewees had difficulty in explaining the meaning of culture and spirituality and their relationship to nursing practice. They also had limited understanding of the Pakistani community, and deficits were identified in meeting the challenges offered by this community. Inadequate implementation of ‘holism’, poor preparation to meet the needs of an ethnically diverse society and the presence of racism in practice settings emerged as explanations for the deficits participants identified between their expectations and the reality in care settings.

Conclusion.  Although ‘holism’ is a relevant concept for enhancing nursing practice, its meaning needs to be further debated in order to avoid a tokenistic approach to its implementation in the care of patients from minority ethnic communities.
Emergency care and narrative knowledge
Authors: Nairn Stuart
Published: September 2004

Background.  Nursing knowledge is a composite of many influences. In an attempt to strengthen nursing knowledge and practice, there have been significant developments in the codification of nursing knowledge as part of the evidence‐based practice movement. Using established research techniques; this has the capacity to enhance clinical practice. However, not all knowledge can be incorporated into this type of academic discourse, and there is growing interest in narrative knowledge. This paper contributes to this sometimes implicit and sometimes explicit critique of dominant paradigms.

Aim.  The aim of this paper is to examine the usefulness of narrative as a means of exploring the world of emergency nursing practice and its contribution to the emotional lifeworld of clinicians.

Method.  A discourse analysis of nursing narratives in their natural settings was carried out. This involved exploration of stories that were not produced for the purposes of research.

Findings.  Narratives can open up social worlds, which escape or be deliberately erased by more formal methods. Contingent and subversive knowledge can contribute to understanding the emotional impact of emergency care.

Conclusion.  These narratives have their own ‘truth’, which should be incorporated into an understanding of what constitutes the lifeworld of emergency nurses.
Involvement of an X family DNA polymerase in double‐stranded break repair in the radioresistant organism Deinococcus radiodurans
Authors: Lecointe François , Shevelev Igor V. , Bailone Adriana , Sommer Suzanne , Hübscher Ulrich
Published: September 2004

DNA polymerases of the X family have been implicated in a variety of DNA repair processes in eukaryotes. Here we show that Deinococcus radiodurans, a highly radioresistant bacterium able to mend hundreds of radiation‐induced double‐stranded DNA breaks, expresses a DNA polymerase belonging to the X family. This novel bacterial polymerase, named PolXDr, was identified as the product of the Deinococcal DR0467 gene. The purified PolXDr protein possesses a DNA polymerase activity that is stimulated by MnCl2, a property of the X family DNA polymerases. Antibodies raised against PolXDr recognized human pol λ, rat pol β and yeast Pol4 and, conversely, antibodies raised against these proteins recognized PolXDr. This immunological cross‐reactivity suggests a high degree of structural conservation among the polymerases of the X family. Lack of PolXDr reduced the rate of repair of double‐stranded DNA breaks and increased cell sensitivity to γ‐rays. PolXDr thus appears to play an important role in double‐stranded DNA break repair in D. radiodurans.
Traffic spotting: poles apart
Authors: Pugsley Anthony P. , Buddelmeijer Nienke
Published: September 2004

Finding out where specific functions are carried out within a bacterial cell has now become technically feasible. Here we consider recent experiments aimed at determining where bacteria translocate proteins across the cytoplasmic membrane using the Sec machinery.
Subcellular sites for bacterial protein export
Authors: Campo Nathalie , Tjalsma Harold , Buist Girbe , Stepniak Dariusz , Meijer Michel , Veenhuis Marten , Westermann Martin , Müller Jörg P. , Bron Sierd , Kok Jan , Kuipers Oscar P. , Jongbloed Jan D. H.
Published: September 2004

Most bacterial proteins destined to leave the cytoplasm are exported to extracellular compartments or imported into the cytoplasmic membrane via the highly conserved SecA‐YEG pathway. In the present studies, the subcellular distributions of core components of this pathway, SecA and SecY, and of the secretory protein pre‐AmyQ, were analysed using green fluorescent protein fusions, immunostaining and/or immunogold labelling techniques. It is shown that SecA, SecY and (pre‐)AmyQ are located at specific sites near and/or in the cytoplasmic membrane of Bacillus subtilis. The localization patterns of these proteins suggest that the Sec machinery is organized in spiral‐like structures along the cell, with most of the translocases organized in specific clusters along these structures. However, this localization appears to be independent of the helicoidal structures formed by the actin‐like cytoskeletal proteins, MreB or Mbl. Interestingly, the specific localization of SecA is dynamic, and depends on active translation. Moreover, reducing the phosphatidylglycerol phospholipids content in the bacterial membrane results in delocalization of SecA, suggesting the involvement of membrane phospholipids in the localization process. These data show for the first time that, in contrast to the recently reported uni‐ExPortal site in the coccoïd Streptococcus pyogenes, multiple sites dedicated to protein export are present in the cytoplasmic membrane of rod‐shaped B. subtilis.
Regulation of root anaerobiosis and carbon translocation by light and root aeration in Isoetes alpinus
Authors: SORRELL B. K.
Published: September 2004

The activity of alcohol dehydrogenase (ADH) was measured in corms and roots of the submerged freshwater macrophyte Isoetes alpinus Kirk. growing in situ, and related to its capacity for internal oxygen transport and to carbohydrate translocation. ADH activity was present in roots but not corms at uniform activity (0.15–0.35 × 10−6 mol  g−1 fresh weight s−1) over the entire plant depth range (3–7 m depth), and was intermediate to that developed in excised roots after 1‐week exposure to either dissolved oxygen at air‐saturation or to anoxia. Responses of photosynthesis and root oxygen release to light intensity confirmed that shoot‐to‐root oxygen transport saturated at similar light intensities to photosynthetic oxygen evolution, but was positive in the dark and at irradiances below the compensation point for photosynthesis, due to contributions to transport by oxygen diffusion from the external medium. Transport of 14C‐labelled photo‐assimilates to roots nevertheless ceased when intact plants were exposed to a combination of leaf darkness and root external anoxia, even when high 14C concentrations were present in shoots, but remained high when the roots were provided with external oxygen. The lack of any control over permeability of the root surface to gases in this species suggested that ADH activity and reduced translocation is most likely caused by development of hypoxic tissues in the apical tissue. These results suggest that reductions in ambient light intensity may have indirect effects on I. alpinus viability by increasing the degree of root hypoxia and impairing carbon partitioning.
Accumulation of pathogenesis‐related (PR) 10/Bet v 1 protein homologues in mulberry (Morus bombycis Koidz.) tree during winter
Authors: UKAJI N. , KUWABARA C. , TAKEZAWA D. , ARAKAWA K. , FUJIKAWA S.
Published: September 2004

Seasonal evaluation of total soluble protein fractions extracted from cortical parenchyma cells of mulberry (Morus bombycis Koidz.) tree identified a predominant 18 kDa protein that was directly correlated to periods of cold acclimation. The 18 kDa protein, designated as WAP18 (winter accumulating 18 kDa proteins) increased from September to December and then gradually decreased until June. The maximum levels of WAP18 were detected in mid‐winter, which corresponds to the maximum freeze tolerance in cortical parenchyma cells of mulberry tree. Two‐dimensional gel electrophoresis confirmed that WAP18 consists of at least three proteins that range between an isoelectric point of 5.0 and 6.0. All three proteins reacted with anti‐WAP18 antibodies, thereby suggesting that they represent individual isoforms. Furthermore, N‐terminal amino acid sequence analysis demonstrated that all three proteins contain high sequence similarity to each other and high homology to pathogenesis‐related (PR) −10/Bet v 1 protein families. The purified WAP18 exhibited in vitro cryoprotective activity for the freeze labile l‐lactate dehydrogenase (LDH) enzyme. These results suggest that WAP18 may function in the freezing tolerance mechanism of cortical parenchyma cells of mulberry tree during winter.
Cadmium‐induced subcellular accumulation of O2·− and H2O2 in pea leaves
Authors: ROMERO‐PUERTAS M. C. , RODRÍGUEZ‐SERRANO M. , CORPAS F. J. , GÓMEZ M. , DEL RÍO L. A. , SANDALIO L. M.
Published: September 2004

Cadmium is a toxic metal that produces disturbances in plant antioxidant defences giving rise to oxidative stress. The effect of this metal on H2O2 and O2·− production was studied in leaves from pea plants growth for 2 weeks with 50 µm Cd, by histochemistry with diaminobenzidine (DAB) and nitroblue tetrazolium (NBT), respectively. The subcellular localization of these reactive oxygen species (ROS) was studied by cytochemistry with CeCl3 and Mn/DAB staining for H2O2 and O2·−, respectively, followed by electron microscopy observation. In leaves from pea plants grown with 50 µm CdCl2 a rise of six times in the H2O2 content took place in comparison with control plants, and the accumulation of H2O2 was observed mainly in the plasma membrane of transfer, mesophyll and epidermal cells, as well as in the tonoplast of bundle sheath cells. In mesophyll cells a small accumulation of H2O2 was observed in mitochondria and peroxisomes. Experiments with inhibitors suggested that the main source of H2O2 could be a NADPH oxidase. The subcellular localization of O2·− production was demonstrated in the tonoplast of bundle sheath cells, and plasma membrane from mesophyll cells. The Cd‐induced production of the ROS, H2O2 and O2·−, could be attributed to the phytotoxic effect of Cd, but lower levels of ROS could function as signal molecules in the induction of defence genes against Cd toxicity. Treatment of leaves from Cd‐grown plants with different effectors and inhibitors showed that ROS production was regulated by different processes involving protein phosphatases, Ca2+ channels, and cGMP.
Inhibition of photosynthesis by high temperature in oak (Quercus pubescensL.) leaves grown under natural conditions closely correlates with a reversible heat‐dependent reduction of the activation state of ribulose‐1,5‐bisphosphate carboxylase/oxygenase
Authors: HALDIMANN P. , FELLER U.
Published: September 2004

Inhibition of the net photosynthetic CO2assimilation rate (Pn) by high temperature was examined in oak (Quercus pubescensL.) leaves grown under natural conditions. Combined measurements of gas exchange and chlorophyll (Chl)afluorescence were employed to differentiate between inhibition originating from heat effects on components of the thylakoid membranes and that resulting from effects on photosynthetic carbon metabolism. Regardless of whether temperature was increased rapidly or gradually,Pndecreased with increasing leaf temperature and was more than 90% reduced at 45 °C as compared to 25 °C. Inhibition ofPnby heat stress did not result from reduced stomatal conductance (gs), as heat‐induced reduction ofgswas accompanied by an increase of the intercellular CO2concentration (Ci). Chl afluorescence measurements revealed that between 25 and 45 °C heat‐dependent alterations of thylakoid‐associated processes contributed only marginally, if at all, to the inhibition ofPnby heat stress, with photosystem II being remarkably well protected against thermal inactivation. The activation state of ribulose‐1,5‐bisphosphate carboxylase/oxygenase (Rubisco) decreased from about 90% at 25 °C to less than 30% at 45 °C. Heat stress did not affect Rubiscoper se, since full activity could be restored by incubation with CO2and Mg2+. Western‐blot analysis of leaf extracts disclosed the presence of two Rubisco activase polypeptides, but heat stress did not alter the profile of the activase bands. Inhibition ofPnat high leaf temperature could be markedly reduced by artificially increasingCi. A highCialso stimulated photosynthetic electron transport and resulted in reduced non‐photochemical fluorescence quenching. Recovery experiments showed that heat‐dependent inhibition ofPnwas largely, if not fully, reversible. The present results demonstrate that inQ. pubescensleaves the thylakoid membranes in general and photosynthetic electron transport in particular were well protected against heat‐induced perturbations and that inhibition ofPnby high temperature closely correlated with a reversible heat‐dependent reduction of the Rubisco activation state.
Oxidative gating of water channels (aquaporins) in Chara by hydroxyl radicals
Authors: HENZLER T. , YE Q. , STEUDLE E.
Published: September 2004

Hydroxyl radicals (*OH) as produced in the Fenton reaction (Fe2+ + H2O2 = Fe3+ + OH– + *OH) have been used to reversibly inhibit aquaporins in the plasma membrane of internodes of Chara corallina. Compared to conventional agents such as HgCl2, *OH proved to be more effective in blocking water channels and was less toxic to the cell. When internodes were treated for 30 min, cell hydraulic conductivity (Lp) decreased by 90% or even more. This effect was reversed within a few minutes after removing the radicals from the medium. In contrast to HgCl2, radical treatment reduced membrane permeability of small lipophilic organic solutes (ethanol, acetone, 1‐propanol, and 2‐propanol) by only 24 to 52%, indicating some continued limited movement of these solutes across aquaporins. The biggest effect of *OH treatment on solute permeability was found for isotopic water (HDO), which largely used water channels to cross the membrane. Inhibition of aquaporins reduced the diffusional water permeability (Pd) by about 70%. For the organic test solutes, which mainly use the bilayer to cross the membrane, channel closure caused anomalous (negative) osmosis; that is, cells had negative reflection coefficients (σs) and were transiently swelling in a hypertonic medium. From the ratio of bulk (Lp or osmotic permeability coefficient, Pf) to diffusional (Pd) permeability of water, the number (N) of water molecules that align in water channels was estimated to be N = Pf/Pd = 46 (on average). Radical treatment decreased N from 46 to 11, a value still larger than unity, which would be expected for a membrane lacking pores. The gating of aquaporins by *OH radicals is discussed in terms of a direct action of the radicals when passing the pores or by an indirect action via the bilayer. The rapid recovery of inhibited channels may indicate an easy access of cytoplasmic antioxidants to closed water channels. As hydrogen peroxide is a major signalling substance during different biotic and abiotic stresses, the reversible closure of water channels by *OH (as produced from H2O2 in the apoplast in the presence of transition metals such as Fe2+ or Cu+) may be downstream of the H2O2 signalling. This may provide appropriate adjustments in water relations (hydraulic conductivity), and a common response to different kinds of stresses.
Expression and Characterisation of the Homodimeric E1 Component of the Azotobacter vinelandii Pyruvate Dehydrogenase Complex
Authors: Hengeveld Annechien F. , Westphal Adrie H. , De Kok Aart
Published: September 2004

We have cloned and sequenced the gene encoding the homodimeric pyruvate dehydrogenase component (Elp) of the pyruvate dehydrogenase complex from Azotobacter vinelandii and expressed and purified the E1p component in Escherichia coli.

Cloned E1p can be used to fully reconstitute complex activity. The enzyme was stable in high ionic strength buffers, but was irreversibly inactivated when incubated at high pH, which presumably was caused by its inability to redimerize correctly. This explains the previously found low stability of the wild‐type E1p component after resolution from the complex at high pH.

Cloned E1p showed a kinetic behaviour exactly like the wild‐type complex‐bound enzyme with respect to its substrate (pyruvate), its allosteric properties, and its effectors. These experiments show that acetyl coenzyme A acts as a feedback inhibitor by binding to the E1p component.

Limited proteolysis experiments showed that the N‐terminal region of E1p was easily removed. The resulting protein fragment was still active with artificial electron acceptors but had lost its ability to bind to the core component (E2p) and thus reconstitute complex activity. E1p was protected against proteolysis by E2p. The allosteric effector pyruvate changed E1p into a conformation that is more resistant to proteolysis.
Characterisation and Properties of an Intracellular Lipid‐Binding Protein from the Tapeworm Moniezia expansa
Authors: Barrett John , Saghir Nahid , Timanova Anna , Clarke Katie , Brophy Peter M.
Published: September 2004

The tapeworm Moniezia expansa contains an extremely abundant cytoplasmic lipid‐binding protein (LBP). It is a small protein consisting of 66 amino acids with a molecular mass of 7943 ± 1.5Da. The amino acid sequence has been established by Edman degradation and confirmed by PCR analysis. The Moniezia LBP shows no sequence similarity with any previously described binding protein, but does show similarity with antigen B from Echinococcus glanulosus and Echinococcus multilocularis and with Taenia crassiceps antigen. The predicted structure for Moniezia LBP shows four helices and a putative tyrosine kinase site on the loop between helix 1 and 2. Each of the four helices has a well defined hydrophobic face. Studies with fluorescent probes suggest a single hydrophobic binding site. Results indicate that the single tryptophan residue in the molecule (Trp41) is involved in ligand binding, and calculation of the Stern‐Volmer quenching constant shows that Trp41 is in a relatively hydrophobic environment.
A Central Role for Water in the Control of the Spin State of CytochromeP‐450scc
Authors: Bancel Frédéric , Bec Nicole , Ebel Christine , Lange Reinhard
Published: September 2004

A previous thermodynamic study [Lange, R., Larroque, C. & Anzenbacher, P. (1992)Eur. J. Biochem. 207, 69–73] demonstrated two conformations (A and B) of cytochromeP‐450scc(SCC), the enzyme which initiates steroid biosynthesis by cleaving the side chain of cholesterol. The conformation found at the lowest temperatures (form A) displays a six‐ligand high‐spin heme iron [Hildebrandt, P., Heibel, G., Anzenbacher, P., Lange, R., Krüger, V. & Stier, A. (1994)Biochemistry 33, 12920–12929]. Analytical centrifugation shows that the oligomeric composition of SCC is the same for the A and the B conformers. However, as revealed by fourth‐derivative ultraviolet spectroscopy, the two conformers differ in the mean environment of the tryptophan residues, which was more polar in the A form. The structural role of water in these two conformations was investigated using the pressure‐jump technique under various pH, temperature and osmotic‐stress conditions. Applying hydrostatic pressure to SCC induced very slow (τ >30 min) biexponential relaxation kinetics corresponding to the high‐spin to low‐spin transition. Analysis of the activation volumes suggested a dissociative mechanism for the A conformer (+45 ml/ mol), and an associative mechanism for the B conformer (−39 ml/mol). Applying osmotic stress to the A form changed its kinetic characteristics to those of the B form. These results are consistent with a model comprising a solvent intake (ten water molecules) between the B and the A conformers and protonation of their respective high‐spin states. The sixth ligand of the high‐spin form in the A conformer involves a water molecule and an unknown constraining structure.
Specificity and Direction of Depolymerization of β‐Poly(L‐malate) Catalysed by Polymalatase from Physarum polycephalum
Authors: Gasslmaier Bernd , Holler Eggehard
Published: September 2004

β‐Poly(l‐malate), a major constituent of nuclei in plasmodia of Physarum polycephalum, is enzymatically degraded to l‐malate after secretion into the culture medium. This depolymerization is specifically catalysed by an endogenous polymalatase. The mode of action and the specificity criteria have been investigated by employing various chemical derivatives of β‐poly(l‐malate), including substitution at the hydroxy‐terminus and carboxy‐terminus of the polymer, esterification of the pending α‐carboxylate, and β‐poly(dl‐malate). The results of the investigation were summarized in a specificity model that involved recognition of the hydroxy‐terminus and of the α‐carboxylate as substituents of the asymmetric carbon in the malic acid unit. Depolymerization proceeded from the hydroxy‐terminus towards the carboxy‐terminus, thereby degrading the polymer to l‐malate. When the terminal β‐carboxylate had been amidated with the fluorescent N‐(1‐naphthyl)ethylenediamine, degradation was normal but was arrested at the level of the terminal β‐carboxy‐substituted dimer. It should be possible to employ polymalatase as a tool for the detection of branching and other modifications of β‐poly(l‐malate).
Pharmacological Concentrations of Suramin Inhibit the Binding of α2‐Macroglobulin to its Cell‐Surface Receptor
Authors: Vassiliou Gerard
Published: September 2004

Suramin is a polysulfated drug used in the treatment of cancer and AIDS. High concentrations (1 mg/ ml) of suramin did not affect the ability of native α2‐macroglobulin (α2M) to inhibit proteinases nor did it prevent conversion of native α2M to the ‘fast’ receptor‐binding form. Nevertheless, pharmacological concentrations (below 250 μg/ml) of suramin prevented the interaction between methylamine‐activated α2M and its receptor, the low‐density‐lipoprotein‐receptor‐related protein. Inhibition was demonstrated at the molecular level and was not due to calcium sequestration by the drug, irreversible denaturation of the receptor, or a non‐specific polyanion effect (since heparin and dextran sulfate did not alter the binding of α2M). The ability of suramin to accelerate the dissociation of pre‐bound α2M was consistent with a non‐competitive mechanism of inhibition although the possibility of a competitive component cannot be eliminated. I discuss how the inhibition of α2M‐binding by suramin may contribute to the antiproliferative properties of this drug.