bluuebunny/crossref_metadata_2025 huggingface dataset:
In vitro studies of a degradable device for controlled‐release of meloxicam
Authors: Çetin Emel Ö. , Buduneli Nurcan , Atlıhan Evren , Kırılmaz Levent
Published: June 2005

Background: Plaque biofilm and associated host responses are the primary factors in the pathogenesis of periodontitis. Delivery of medications directly into the periodontal pockets to suppress or eradicate the pathogenic microbiota or modulate the inflammatory response has attracted significant interest to limit periodontal tissue destruction. The aim of the present study was twofold: (1) to describe the development of a biodegradable controlled‐release device containing meloxicam as the therapeutic agent and (2) to evaluate the in vitro release of meloxicam from this device into different release media.

Methods: Films of cross‐linked gelatin matrix containing meloxicam were prepared, hardened for various time periods and cut in a form to fit to the periodontal pocket anatomy. The release of active agents was studied separately in 10 ml distilled water, artificial saliva and pH 7.4 phosphate buffer at 37°C. Apparatus Vibrax was used at 120 r.p.m. Determinations were carried out spectrophotometrically, and the release profiles were plotted as a function of time. The results were evaluated by the similarity test.

Results: The release rates of meloxicam from the hardened (1h, 4h, 8 h) formulations were slower than the unhardened formulation in all the three release media. Increasing the hardening time decreased the release rates. The overall release rates were similar in artificial saliva and pH 7.4 phosphate buffer, while it was lower in distilled water.

Conclusions: As a conclusion, cross‐linked gelatin matrix films may be considered as a suitable inert material for obtaining a prolonged local release of meloxicam as an adjunct to the mechanical periodontal treatment. As required, further in vitro and in vivo studies will be performed before starting clinical applications of this controlled‐release formulation of the anti‐inflammatory agent.
Thickness of gingiva in association with age, gender and dental arch location
Authors: Vandana K. L. , Savitha B.
Published: June 2005

Background: It has been long known that the clinical appearance of healthy marginal periodontium differs from subject to subject and even among different tooth types. Many features are genetically determined; others seem to be influenced by tooth size, shape and position and biological phenomena such as gender, growth and age.

Aim: The purpose of this study was to determine the thickness of facial gingiva among Indians and its association with age, gender and dental arch.

Methods: The study group included 16 males and 16 females with an age range of 16–38 years. Gingival thickness was assessed in the maxillary and mandibular anteriors by transgingival probing.

Results: It was observed that the younger age group had significantly thicker gingiva than that of the older age group. The gingiva was found to be thinner in females than males and, in the mandibular arch than the maxilla.

Conclusion: In the present study, it was concluded that gingival thickness varies according to age, gender and dental arch.
Healing of intra‐bony defects following treatment with a composite bovine‐derived xenograft (Bio‐Oss Collagen) in combination with a collagen membrane (Bio‐Gide PERIO)
Authors: Sculean Anton , Chiantella Giovanni C. , Windisch Péter , Arweiler Nicole B. , Brecx Michel , Gera István
Published: June 2005

Aim: The purpose of the present study was to compare clinically the treatment of deep intra‐bony defects with a combination of a composite bovine‐derived xenograft (BDX Coll) and a bioresorbable collagen membrane [guided tissue regeneration (GTR)] to access flap surgery only.

Methods: Thirty‐two patients, each of whom displayed one intra‐bony defect, were treated either with BDX Coll+GTR (test) or with access flap surgery (control). The results were evaluated at 1 year following therapy.

Results: No differences in any of the investigated parameters were observed at baseline between the two groups. Healing was uneventful in all patients. At 1 year after therapy, the test group showed a reduction in the mean probing depth (PD) from 8.3±1.5 to 2.9±1.3 mm (p<0.001) and a change in the mean clinical attachment level (CAL) from 9.4±1.3 to 5.3±1.5 mm (p<0.0001). In the control group, the mean PD was reduced from 8.0±1.2 to 4.4±1.7 mm (p<0.001) and the mean CAL changed from 9.6±1.3 to 7.9±1.6 mm (p<0.01). The test treatment resulted in statistically higher PD reductions (p0.05) and CAL gains (p<0.001) than the control one. In the test group, all sites (100%) gained at least 3 mm of CAL. In this group, a CAL gain of 3 or 4 mm was measured at 10 sites (62%), whereas at six sites (38%), the CAL gain was 5 or 6 mm. In the control group, no CAL gain occurred at three sites (19%), whereas at 10 sites (62%), the CAL gain was only 1 or 2 mm. A CAL gain of 3 mm was measured in three defects (19%).

Conclusions: Within the limits of the present study, it can be concluded that the combination of BDX Coll+GTR resulted in significantly higher CAL gains than treatment with access flap surgery alone, and thus appears to be a suitable alternative for treating intra‐bony periodontal defects.
A regimen of systematic periodontal care after removal of impacted mandibular third molars manages periodontal pockets associated with the mandibular second molars
Authors: Leung W. Keung , Corbet Esmonde F. , Kan Kwok Wing , Lo Edward C. M. , Liu Jerry K. S.
Published: June 2005

Aim: This randomized, single‐blinded control trial investigated the local effects of periodontal care on the mandibular second molar delivered during and after impacted third molar surgical extraction.

Method: Thirty subjects (50% male, 32.1±7.8 years) out of 35 enrolled, with a mesio‐angular impacted mandibular third molar, having probing pocket depth (PPD) >5 mm at adjacent second molar distal, and crestal radio‐lucency between the two teeth, completed the study. Oral hygiene instruction, scaling and caries stabilization were performed before surgery. Controls (n=16) had their third molar extracted followed by standard socket debridement. Test group subjects (n=14) received the same treatment, except that before wound closure the operator was informed of the group allocation and ultrasonic root debridement on the second molar was performed, followed by a three‐visit plaque control programme.

Results: Six months post‐extraction, statistically significantly (p<0.007) better plaque control and shallower probing depths were observed at test second molars' distal (%plaque=21; PPD=3.2±1.2 mm) than at control second molars (%plaque=88; PPD=5.2±0.7 mm).

Conclusions: The periodontal interventions investigated prevented residual pockets on periodontally involved second molars 6 months after ipsilateral impacted mandibular third molar removal.
Chemical sympathectomy inhibits periodontal disease in Fischer 344 rats
Authors: Breivik Torbjørn , Gundersen Yngvar , Opstad Per Kristian , Fonnum Frode
Published: June 2005

Objective:  The responsiveness of the sympathetic nervous system (SNS) and the hypothalamic–pituitary–adrenal (HPA) axis plays a major role in immune regulation and for the outcome of infections and inflammatory disorders. This study was designed to investigate whether chemical SNS denervation with the noradrenaline‐selective neurotoxic drug 6‐hydroxydopamine (6‐OHDA), which destroys peripheral noradrenaline terminals, would influence immune responses to Gram‐negative bacterial lipopolysaccharide (LPS) stimulation, and the progression of ligature‐induced periodontal disease in Fischer 344 rats.

Material and methods:  6‐OHDA (40–60 µg/kg) or vehicle was injected intraperitoneally (i.p.) on days 1, 3 and 5, 10 days before application of the ligatures, and thereafter weekly in doses of 80 µg/kg. Periodontal disease was assessed when the ligatures had been in place for 49 days. At 24 and 2 h before decapitation, all rats received LPS (150 µg/kg i.p.) to induce a robust immune and HPA axis response.

Results:  The 6‐OHDA‐treated rats showed significantly reduced bone loss as measured by digital X‐rays (p < 0.01), and enhanced levels of the cytokines transforming growth factor‐β (p = 0.05) and interleukin‐6 (p = 0.05), as well as the HPA axis derived hormone corticosterone (p = 0.01), induced by LPS stimulation.

Conclusions:  6‐OHDA‐induced chemical sympathectomy inhibits ligature‐induced periodontal disease in this model. This effect may be attributable to the well‐documented ability of the SNS to regulate immune system function primarily via the adrenergic neurotransmitter noradrenaline released at sympathetic nerve terminals. The enhanced HPA axis activation may be a compensatory response that reduces the T helper (Th)2 to Th1 skewing effect of treatment with 6‐OHDA.
Cytoskeleton and surface structures of cells directly attached to the tooth in the rat junctional epithelium
Authors: Ishikawa Hiroki , Hashimoto Sadamitsu , Tanno Michie , Ishikawa Tatsuya , Tanaka Teruo , Shimono Masaki
Published: June 2005

Objective:  It is still an open question whether cells directly attached to the tooth (DAT) cells are migratory or non‐migratory cells. The purpose of this study was to examine cytoskeletal and surface structures of DAT cells that might be involved in migration.

Methods:  We investigated the distribution of stress fibers composed of actin filaments in DAT cells using phallacidin fluorescent dye methods in a confocal laser scanning microscope. To observe the three‐dimensional structure of the DAT cell surface, the osmium maceration scanning electron microscope (SEM) method, which removes various soluble materials between DAT cells and the enamel, was employed.

Results:  Stress fibers were found in the most apically located DAT cells, and were arranged in parallel to the presumable cervical‐line, whereas some of the fibers ran parallel to the tooth axis in the more coronally located DAT cells. The parallel arrangement to the tooth axis of the fibers may be involved with migration for turnover, and the parallel accumulation to the presumable cervical‐line may be concerned with the cervical contraction of DAT cells. Osmium maceration SEM images at high magnification revealed the existence of microvilli‐like structures on the enamel surfaces (facing to the tooth surface) of DAT cells after removal of the soluble matrices. The thicknesses of the microvilli‐like structures on the enamel surfaces and cell processes of intercellular bridges were significantly different.

Conclusion:  DAT cells possess stress fibers arranged in parallel to the tooth axis and to the presumable cervical‐line in the cytoplasm, and microvilli‐like structures on their enamel surfaces. These results suggest that these structures contribute to DAT cell migration.
Rhyme and Ritual: a new approach to teaching children to read and write
Authors: Merttens Ruth , Robertson Catherine
Published: June 2005

This paper concerns an approach to raising literacy standards which is rather different from the prevailing orthodoxy – the Rhyme and Ritual project. The project is run by the Hamilton Reading Project, which comprises a series of initiatives funded by the Hamilton Trust, an educational charity, and implemented in fifteen primary schools in a large and socio‐economically deprived city area in southern England. It incorporates both a supposedly ‘old‐fashioned’ traditional notion – that children can be supported in learning to read through approaching a text known off by heart (the phrase is important, since the text must not only be familiar but also pleasurable to the individual child) – and also the currently valued approach of expanding and extending children's appropriation and use of elaborated language, particularly in relation to imaginative, descriptive and expressive writing. It is the former aspect of the Rhyme and Ritual project, namely the provision of short texts to be memorised by young children and then read from ‘text only’ books (with decoration but no illustrations) that we believe is uncommon as the basis of an educational initiative with the overt aim of raising literacy standards. The article gives a detailed outline of this initiative, with its two‐pronged and ‘pincer’ approach, and also some indication of how it is succeeding.
Renal Replacement Therapy in Slovenia: 2003 Annual Report*
Authors: Buturović‐Ponikvar Jadranka ,   the Expert Group for Dialysis in Slovenia
Published: June 2005

Abstract:  The total number of end‐stage renal disease patients treated by renal replacement therapy increased from 1584 on 31 December 2002 to 1661 on 31 December 2003 (4.9% increase). Of these patients, 70.5% were treated by hemodialysis, 7.0% by peritoneal dialysis and 22.5% had a functioning renal graft. The patients were treated at 18 dialysis centers and one transplant center. The number of prevalent patients treated by renal replacement therapy per million of the population (p.m.p.) was 846 at the end of 2003. The number of incident (new) patients in 2003 was 131 p.m.p. The gross mortality rate of dialysis patients was stable through the years of the study and reached 11.8% in 2003. 57.6% of new patients starting hemodialysis were ≥ 65 years old and 23.2% were diabetics. Epoetin therapy was prescribed to 89.8% of dialysis patients. The number of patients positive for hepatitis B or hepatitis C viruses is stable and low (3.1% of all dialysis patients).
Cardiac Troponin T in Patients With Kidney Disease
Authors: Hojs Radovan
Published: June 2005

Abstract:  Atherosclerosis is accelerated in dialysis patients and cardiovascular mortality is up to 20 times higher than in the general population. Cardiac troponin T (cTnT) is a sensitive marker of myocardial necrosis and studies have confirmed the superiority of this marker over traditional cardiac enzymes. Elevated cTnT has been observed in patients with various degrees of renal failure and treatment modalities in the absence of an acute coronary event. The possibility that increased troponins reflect decreased clearance or analytical interference from uremic serum is unlikely. It is accepted that cTnT detected in serum from patients with end‐stage renal failure is derived from myocytes and this effect could be caused by subclinical myocardial ischemic release of troponin, myocardial remodeling, or from uremic pericarditis or myocarditis. The significance of cTnT in patients with different degrees of renal failure and different treatment modalities is presented in this review.
Epoetin Responsiveness in Peritoneal Dialysis Patients: A Multi‐center Slovenian Study
Authors: Pajek Jernej , Bučar‐Pajek Maja , Grego Katarina , Guček Andrej , Bevc Sebastjan , Ekart Robert , Vujkovac Bojan , Golob‐Kosmina Polona , Kandus Aljoša , Bren Andrej F
Published: June 2005

Abstract:  The objective of our study was to assess the influence of residual renal function and other factors on epoetin requirements in chronic peritoneal dialysis patients. Fifty‐one stable patients (mean age ± SD: 52 ± 13 years; 20 women) without recent bleeding, bone marrow disease or malignancy were recruited in four Slovenian centers. The target hemoglobin was above 110 g/L. The peritoneal equilibration test results and relevant clinical and laboratory parameters were recorded. The epoetin resistance index was expressed as a weekly epoetin dose/body weight/hemoglobin concentration. Twenty‐four percent of the patients did not need epoetin treatment, the rest were treated with epoetin‐beta in a dose of 70 ± 56 U/kg per week s.c.; the hemoglobin concentration was 124 ± 15 g/L. Ferritin >100 µg/L and transferrin saturation >20% fulfilled 63% of patients whose epoetin resistance index was not significantly lower (0.43 ± 0.5 U/kg per week per g/L vs 0.6 ± 0.72 U/kg per week per g/L, P = 0.502). No difference was found between diabetic and non‐diabetic patients. Treatment with angiotensin system antagonists, but not with aluminum phosphate binders, was associated with increased epoetin resistance index (0.56 ± 0.59 vs 0.3 ± 0.4 U/kg per week per g/L, P = 0.038). No correlation between epoetin resistance index and residual glomerular filtration rate was found (r = −0.2, P = 0.173). A multiple linear regression analysis showed C‐reactive protein, intact parathormone level, female sex and treatment with angiotensin system antagonists to be the independent predictors influencing epoetin resistance index. Our results show that systemic inflammation, secondary hyperparathyroidism and angiotensin system antagonist treatment are the most important modifiable parameters affecting epoetin requirements in stable peritoneal dialysis patients.
Citrate Anticoagulation for Single‐needle Hemodialysis: Safety and Efficacy
Authors: Buturović‐Ponikvar Jadranka , Gubenšek Jakob , Ponikvar Rafael
Published: June 2005

Abstract:  Single‐needle hemodialysis can be the only option in some patients and requires full heparinization. The aim of our retrospective clinical study was to evaluate the safety and efficacy of regional citrate anticoagulation for single‐needle hemodialysis. Citrate anticoagulation was performed during 41 single‐needle hemodialysis procedures in 24 patients at risk of bleeding, using 4% trisodium citrate, 1 M CaCl2 and calcium‐free dialysate. Safety was assessed by the percentage of procedures that were terminated prematurely or changed to another modality due to citrate‐related complications and by incidence of important hypocalcemia. Efficacy was evaluated by visually assessing  clot  formation  in  the  circuit.  Five  per  cent  of  the procedures were terminated prematurely. Important hypocalcemia was recorded in 34% of the procedures. Anticoagulation was suboptimal in 17% of the procedures, but none of the systems clotted. The median dialyzer assessment grade was excellent. The average protocol parameters  were:  blood  flow  244 ± 27 mL/min,  starting  rate of citrate 191 ± 19 mL/h, starting rate of calcium 6.7 ± 1.1 mL/h. In the first hour, ionized calcium decreased in 67% of the procedures by 0.08 ± 0.05 mmol/L. During the entire procedure, ionized calcium decreased in 80% of the cases by 0.17 ± 0.09 mmol/L. There was a significant, but small increase in sodium (135 ± 4 vs 137 ± 4 mmol/L) and no increase in bicarbonate. Citrate anticoagulation during single‐needle hemodialysis, according to our protocol, is safe and effective. Close monitoring of ionized calcium is mandatory. The calcium infusion rate should frequently be increased to correct hypocalcemia. The increased starting rate of calcium should be evaluated.
Effects of Handgrip Training and Intermittent Compression of Upper Arm Veins on Forearm Vessels in Patients With End‐stage Renal Failure
Authors: Rus Rina , Ponikvar Rafael , Kenda Rajko B , Buturović‐Ponikvar Jadranka
Published: June 2005

Abstract:  The purpose of our study was to assess the influence of handgrip training and intermittent compression of the upper arm veins on forearm arteries and veins. Eighteen chronic hemodialysis patients performed daily handgrip training for 8 weeks using a rubber ring, together with daily intermittent compression of the upper arm veins by elastic band. The forearm circumference, maximal handgrip strength, and arterial and vein parameters, including endothelium‐dependent vasodilatation, were measured at the beginning, and after 4 and 8 weeks (using ultrasound scanning). The maximal handgrip strength and forearm circumference increased significantly. The radial artery diameters were significantly higher after 8 weeks of training (1.89 mm ± 0.10 at the beginning, 1.95 ± 0.10 mm after 8 weeks, P = 0.007), and endothelium‐dependent vasodilatation was also found to be increased after 4 and 8 weeks of both activities. The venous parameters before tourniquet placement increased significantly after 8 weeks (2.40 ± 0.16 mm at the beginning, 2.62 ± 0.17 mm after 8 weeks, P = 0.014), and the venous parameters after tourniquet placement increased significantly after 4 and 8 weeks (3.36 ± 0.17 mm at the beginning, 3.51 ± 0.18 mm after 4 weeks, P = 0.009), 3.68 ± 0.18 mm after 8 weeks, P < 0.001). The distensibility of veins was preserved. Our results showed that handgrip training and intermittent compression of the upper arm veins, performed daily, increase the diameter of forearm arteries and veins and improve endothelium‐dependent vasodilatation.
Temporary Hemodialysis Catheters as a Long‐term Vascular Access in Chronic Hemodialysis Patients
Authors: Ponikvar Rafael , Buturović‐Ponikvar Jadranka
Published: June 2005

Abstract:  The objective was to review our experience with temporary, precurved, jugular catheters used for long‐term vascular access in chronic hemodialysis patients. Thirty chronic hemodialysis patients, 14 men and 16 women, with an average age of 65.3 ± 13.5 years (30–90 years), treated by dialysis for 1 month to 30 years (average ± SD, 6.3 ± 8.1 years), had single lumen, ‘temporary’ precurved non‐tunneled jugular catheters placed into the right jugular vein as permanent vascular access, with 4% trisodium citrate as a locking solution and mupirocin at the exit site. Hemodialysis catheters were used for vascular access on average for 9.1 ± 6.5 months, (1–22.7 months), and for a total of 271.7 months (8151 days). Average catheter functioning time was 3.1 ± 1.9 months (0.5–10 months). The total number of side‐effects was 55 (6.7/1000 catheter days), including 26 cases of thrombosis (3.2/1000 catheter days), 9 ruptures of the catheter (1.1/1000 catheter days), 15 catheter malfunctions (1.8/1000 catheter days), 2 exit site infections (0.2/1000 catheter days), 2 bacteremias (0.2/1000 catheter days), 1 avulsion of the catheter (0.1/1000 catheter days), and 2 catheters were removed because an AV fistula was successfully used. In 21 patients single‐needle hemodialysis was performed, mean blood flow 251 ± 16 mL/min (250–300), mean Kt/V 0.96 ± 0.16 (0.72–1.27) and in 9 patients double‐needle hemodialysis was performed (catheter and peripheral vein) with mean blood flow 252 ± 14 mL/min (200–300), mean Kt/V 1.63 ± 0.25 (1.21–1.96). ‘Temporary’ jugular single lumen non‐tunneled hemodialysis catheters, with 4% citrate as locking solution and mupirocin ointment at the exit site provided good long‐term vascular access with acceptable functioning time and low infection rate. The main reasons for catheter exchange or removal were malfunction and mechanical damage of the catheter.
Increased Ethyl Mercury Load in Protein A Immunoadsorption
Authors: Marn‐Pernat Andreja , Buturović‐Ponikvar Jadranka , Logar Martina , Horvat Milena , Ponikvar Rafael
Published: June 2005

Abstract:  Immunoadsorption is an adsorption technique for extracorporeal removal of circulating autoantibodies in autoimmune diseases. To prevent microbial growth during storage, the protein A columns are primed with thiomersal, which contains toxic ethyl mercury, which may be released during the procedure and potentially begin to accumulate and become toxic. To reduce the thiomersal‐related mercury release during immunoadsorption treatment, we introduced a modified rinsing solution containing N‐acetylcysteine, which is an avid mercury scavenger. Thirteen patients received 17 protein A immunoadsorption treatments and their venous blood samples were collected immediately before and after each session. The total blood mercury levels were measured by atomic absorption spectrometry, and the ethyl mercury levels by atomic fluorescence spectrometry. Following the manufacturer's recommendations, we used 600 mg of N‐acetylcysteine to rinse the mercury from protein‐loaded columns before each immunoadsorption treatment. After immunoadsorption, the ethyl mercury levels increased from 0.148 ± 0.402 ng/g to 2.026 ± 1.944 ng/g (P < 0.001), and the total blood mercury levels increased from 2.447 ± 3.065 ng/g to 20.437 ± 28.603 ng/g (P = 0.02). The post‐treatment values of total blood mercury exceeded the upper safety level of 5 ng/g in all 17 immunoadsorption treatments, but no patient developed clinical signs of mercury toxicity. The results of our study showed an increase in total blood mercury and ethyl mercury levels during the immunoadsorption treatments, suggesting mercury release from thiomersal‐primed columns despite the addition of N‐acetylcysteine to the rinsing solution.
Leukocytapheresis Therapy Modulates Circulating T cell Subsets in Patients With Ulcerative Colitis
Authors: Andoh Akira , Tsujikawa Tomoyuki , Inatomi Osamu , Deguchi Yasuyuki , Sasaki Masaya , Obata Hirozumi , Mitsuyama Keiichi , Fujiyama Yoshihide
Published: June 2005

Abstract:  The aim of this study was to elucidate the molecular mechanisms responsible for the therapeutic effects of leukocytapheresis (LCAP). We investigated the alterations in circulating T cell subsets after LCAP therapy in ulcerative colitis (UC) patients. Eighteen patients with UC were enrolled. Fourteen patients were responders, and four patients were non‐responders. Peripheral venous blood was obtained within 5 min before and 5 min after LCAP therapy. Flow cytometric analysis for T cell markers and intracellular interferon (IFN)‐γ (Th1) and interleukin (IL)‐4 (Th2) was then performed. The average numbers of lymphocytes, T and B cells were significantly decreased after LCAP therapy, respectively (P < 0.01). The numbers of CD4+ and CD8+ T cells were also significantly decreased, respectively (P < 0.01), but the CD4+/CD8+ ratio was not changed. The number of CD45RO+CD4+ memory T cells was significantly decreased. The number of CD25+CD4+ T cells tended to decrease after LCAP therapy (not significant). However, the ratio of CD25+CD4+‐cells/CD25–CD4+‐cells was significantly increased (P < 0.05). The number of IFN‐γ‐positive (Th1) cells was significantly decreased after LCAP therapy, but there was no significant change in the number of IL‐4‐positive (Th2) cells. The Th1/Th2 ratio was significantly decreased after LCAP therapy. Some of the immuno‐suppressive effects of LCAP therapy may be associated with a modulation of circulating T cell subsets.
Surfing a Standing Wave
Authors: de Campos Valadares Eduardo , Alves Esdras Garcia
Published: June 2005

Local “reversal of gravity” can be simulated with an inverted pendulum whose pivot is made to oscillate vertically. A beautiful demonstration of this surprising effect can be found in Ref. 1. In this case, the pendulum is a piece of plastic straw and its pivot pin is fixed at the end of a plastic ruler that is made to oscillate vertically by a small eccentric motor. A theoretical treatment of this inverted pendulum may be found in Ref. 2.
Saw Blades and Resonance
Authors: Liebl Michael
Published: June 2005

This paper describes an inexpensive, classroom experiment that allows students to quantitatively investigate resonance using a hacksaw blade. The blade clamped to the edge of a table forms a cantilever that may vibrate at any of a number of preferred frequencies. A small cylindrical magnet is fixed to the saw blade. An electromagnetic coil powered by a frequency generator causes large-amplitude vibrations of the saw blade at the resonant frequencies. Vibrations of a similar system, a vibrating car antenna, have been discussed by Newburgh and Newburgh.1 The dramatic increases in the oscillation amplitude are both instructive and fascinating. Analogies may be drawn to systems ranging from a child on a swing to the Tacoma Narrows bridge.
Synergistic Regulation of Competence Development inBacillus subtilisby Two Rap-Phr Systems
Authors: Bongiorni Cristina , Ishikawa Shu , Stephenson Sophie , Ogasawara Naotake , Perego Marta
Published: June 2005

The 11 Rap proteins ofBacillus subtiliscomprise a conserved family of tetratricopeptide (TPR)-containing regulatory proteins. Their activity is inhibited by specific Phr pentapeptides produced from the product ofphrgenes through an export-import maturation process. We found that one of the proteins, namely RapF, is involved in the regulation of competence to DNA transformation. The ComA response regulator and transcription factor for initiation of competence development is the target of RapF. Specific binding of RapF to the carboxy-terminal DNA-binding domain of ComA inhibits the response regulator's ability to bind its target DNA promoters. The PhrF C-terminal pentapeptide, QRGMI, inhibits RapF activity. The activity of RapF and PhrF in regulating competence development is analogous to the previously described activity of RapC and PhrC (L. J. Core and M. Perego, Mol. Microbiol.49:1509-1522, 2003). In fact, the RapF and PhrF pair of proteins acts synergistically with RapC and PhrC in the overall regulation of the ComA transcription factor. Since the transcription of the RapC- and RapF-encoding genes is positively regulated by their own target ComA, an autoregulatory circuit must exist for the competence transcription factor in order to modulate its activity.
pyd
Genes of
Rhizobium
sp. Strain TAL1145 Are Required for Degradation of 3-Hydroxy-4-Pyridone, an Aromatic Intermediate in Mimosine Metabolism
Authors: Awaya Jonathan D. , Fox Paul M. , Borthakur Dulal
Published: June 2005

Rhizobium
sp. strain TAL1145 degrades the
Leucaena
toxin mimosine and its degradation product 3-hydroxy-4-pyridone (HP). The aim of this investigation is to characterize the
Rhizobium
genes for HP degradation and transport. These genes were localized by subcloning and mutagenesis on a previously isolated cosmid, pUHR263, containing
mid
genes of TAL1145 required for mimosine degradation. Two structural genes,
pydA
and
pydB
, encoding a metacleavage dioxygenase and a hydrolase, respectively, are required for degradation of HP, and three genes,
pydC
,
pydD
, and
pydE
, encoding proteins of an ABC transporter, are involved in the uptake of HP by TAL1145. These genes are induced by HP, although both
pydA
and
pydB
show low levels of expression without HP.
pydA
and
pydB
are cotranscribed, while
pydC
,
pydD
, and
pydE
are each transcribed from separate promoters. PydA and PydB show no homology with other dioxygenases and hydrolases in
Sinorhizobium meliloti
,
Mesorhizobium loti
, and
Bradyrhizobium japonicum
. Among various root nodule bacteria, the ability to degrade mimosine or HP is unique to some
Leucaena
-nodulating
Rhizobium
strains.
Host- and Tissue-Specific Pathogenic Traits of
Staphylococcus aureus
Authors: van Leeuwen Willem B. , Melles Damian C. , Alaidan Alwaleed , Al-Ahdal Mohammed , Boelens Hélène A. M. , Snijders Susan V. , Wertheim Heiman , van Duijkeren Engeline , Peeters Justine K. , van der Spek Peter J. , Gorkink Roy , Simons Guus , Verbrugh Henri A. , van Belkum Alex
Published: June 2005

Comparative genomics were used to assess genetic differences between
Staphylococcus aureus
strains derived from infected animals versus colonized or infected humans. A total of 77 veterinary isolates were genetically characterized by high-throughput amplified fragment length polymorphism (AFLP). Bacterial genotypes were introduced in a large AFLP database containing similar information for 1,056 human
S. aureus
strains. All
S. aureus
strains isolated from animals in close contact with humans (e.g., pet animals) were predominantly classified in one of the five main clusters of the AFLP database (cluster I). In essence, mastitis-associated strains from animals were categorized separately (cluster IVa) and cosegregated with bacteremia-associated strains from humans. Distribution of only 2 out of 10 different virulence genes differed across the clusters. The gene encoding the toxic shock syndrome protein (
tst
) was more often encountered among veterinary strains (
P
< 0.0001) and even more in the mastitis-related strains (
P<
0.0001) compared to human isolate results. The gene encoding the collagen binding protein (
cna
) was rarely detected among invasive human strains. The virulence potential, as indicated by the number of virulence genes per strain, did not differ significantly between the human- and animal-related strains. Our data show that invasive infections in pets and humans are usually due to
S. aureus
strains with the same genetic background. Mastitis-associated
S. aureus
isolated in diverse farm animal species form a distinct genetic cluster, characterized by an overrepresentation of the toxic shock syndrome toxin superantigen-encoding gene.
Sialylation of Group B Streptococcal Capsular Polysaccharide Is Mediated bycpsKand Is Required for Optimal Capsule Polymerization and Expression
Authors: Chaffin D. O. , Mentele L. M. , Rubens C. E.
Published: June 2005

Several bacterial pathogens have evolved the means to escape immune detection by mimicking host cell surface carbohydrates that are crucial for self/non-self recognition. Sialic acid, a terminal residue on these carbohydrates, inhibits activation of the alternate pathway of complement by recruiting the immune modulating molecule factors H, I, and iC3b. Sialylation of capsular polysaccharide (CPS) is important for virulence of group B streptococci (GBS), a significant human pathogen. We previously reported thatcpsK, a gene within thecpslocus of type III GBS, could complement a sialyltransferase deficientlstmutant ofHaemophilus ducreyi, implicating its role in sialylation of the GBS capsule. To explore the function ofcpsKin GBS capsule production, we created a mutant incpsK. Immunoblot analysis and enzyme-linked immunosorbent assay using anti-type III CPS antisera demonstrated that the mutant CPS did not contain sialic acid. This was confirmed by high-performance liquid chromatography after mild acid hydrolysis of the CPS. Although increased CPS chain length was seen for this strain, CPS production was <20% of the parental isolate. An episomalcpsKcopy restored synthesis of sialo-CPS to wild-type levels. These data support our hypothesis thatcpsKencodes the GBS CPS sialyltransferase and provide further evidence that lack of CPS oligosaccharide sialylation reduces the amount of CPS expressed on the cell surface. These observations also imply that one or more of the components involved in synthesis or transport of oligosaccharide repeating units requires a sialo-oligosaccharide for complete activity.
Activities of the
Serratia marcescens
Heme Receptor HasR and Isolated Plug and β-Barrel Domains: the β-Barrel Forms a Heme-Specific Channel
Authors: Létoffé Sylvie , Wecker Karine , Delepierre Muriel , Delepelaire Philippe , Wandersman Cécile
Published: June 2005

The
Serratia marcescens
hemophore-specific outer membrane receptor HasR is a member of the TonB-dependent family of autoregulated receptors. It can transport either heme itself or heme bound to the hemophore HasA. On the basis of sequence and functional similarities with other TonB-dependent outer membrane receptors whose three-dimensional structures have been determined, a HasR structure model was proposed. The mature HasR protein comprises a 99-residue amino-terminal extension necessary for
hasR
transcription, followed by a plug domain of 139 amino acids and a β-barrel domain inserted in the outer membrane, the lumen of which is closed by the plug. This model was used to generate
hasR
deletions encoding HasR proteins with the native signal peptides but lacking either the N-terminal regulatory extension or encoding the plug or the β-barrel alone. The protein lacking the N-terminal extension, HasR Δ11-91, was incorporated in the outer membrane and was fully functional for active uptake of free and hemophore-bound heme. The HasR β-barrel, Δ11-192, was also incorporated in the outer membrane and bound the hemophore but expressed no active heme transport properties. The HasR plug remained in the periplasm. Coexpression of the plug and the β-barrel allowed partial plug insertion in the outer membrane, demonstrating that these two HasR domains interact in vivo. The β-barrel and the plug also interact in vitro. Nevertheless, the two domains did not complement each other to reconstitute an active TonB-dependent receptor for free or hemophore-bound heme uptake. Production of the β-barrel alone selectively increased passive diffusion of heme but not of other exogenous compounds. A mutation at histidine 603, which is required for heme uptake through the wild-type receptor, abolished heme diffusion, showing that HasR Δ11-192 forms a specific heme channel.
Methylocella
Species Are Facultatively Methanotrophic
Authors: Dedysh Svetlana N. , Knief Claudia , Dunfield Peter F.
Published: June 2005

All aerobic methanotrophic bacteria described to date are unable to grow on substrates containing carbon-carbon bonds. Here we demonstrate that members of the recently discovered genus
Methylocella
are an exception to this. These bacteria are able to use as their sole energy source the one-carbon compounds methane and methanol, as well as the multicarbon compounds acetate, pyruvate, succinate, malate, and ethanol. To conclusively verify facultative growth, acetate and methane were used as model substrates in growth experiments with the type strain
Methylocella silvestris
BL2. Quantitative real-time PCR targeting the
mmoX
gene, which encodes a subunit of soluble methane monooxygenase, showed that copies of this gene increased in parallel with cell counts during growth on either acetate or methane as the sole substrate. This verified that cells possessing the genetic basis of methane oxidation grew on acetate as well as methane. Cloning of 16S rRNA genes and fluorescence in situ hybridization with strain-specific and genus-specific oligonucleotide probes detected no contaminants in cultures. The growth rate and carbon conversion efficiency were higher on acetate than on methane, and when both substrates were provided in excess, acetate was preferably used and methane oxidation was shut down. Our data demonstrate that not all methanotrophic bacteria are limited to growing on one-carbon compounds. This could have major implications for understanding the factors controlling methane fluxes in the environment.
Far-Infrared Absorption of Self-Assembled Semiconductor Rings
Authors: Planelles Josep , Climente Juan I.
Published: June 2005

A theoretical description of far-infrared spectroscopy experiments on self-assembled quantum rings in a magnetic field [Lorke A. et al.: Phys. Rev. Lett. 2000, 84, 2223] is reported which, for the first time, accounts for the full set of experimental resonances. In calculations a 3D effective-mass model with a realistic finite step-like confinement potential, including strain and Coulomb effects is used. A bimodal distribution of ring sizes is assumed.
Assessment of calcium status in Maine forests: review and future projection
Authors: Huntington T G
Published: June 2005

Forest harvesting and acidic deposition can cause substantial decreases in the calcium (Ca) inventory of forest soils if such losses are not replenished through mineral weathering, atmospheric deposition, or fertilization. The net balance between losses and gains defines the forest Ca status. Site-specific studies have measured Ca pools and fluxes in Maine forests, but no synthesis has been published. In this paper, I review the literature on forest Ca and assess the current status and potential future trends. Forest soils in Maine are currently at lesser risk of Ca depletion compared with many forest soils in the central and southeastern United States, because levels of acidic deposition and rates of Ca accumulation in trees are lower in Maine. The rate of Ca accumulation in trees is reduced in Maine as a result of lower growth rates and a higher proportion of conifer trees that require less Ca than hardwoods. However, field-scale biogeochemical studies in Maine and New Hampshire, and regional estimates of harvest removals and soil inventories coupled with low weathering estimates, indicate that Ca depletion is a realistic concern in Maine. The synthesis of site-specific and regional data for Maine in conjunction with the depletion measured directly in surrounding areas indicates that the Ca status of many forest soils in Maine is likely declining. Ca status could decrease further in the future if forest growth rates increase in response to climate trends and recovery from insect-induced mortality and excessive harvesting in recent years. Proposed climate change induced reductions in spruce and fir and increases in hardwoods would also increase the risk of Ca depletion.
Multispectral remote sensing of landscape level foliar moisture: techniques and applications for forest ecosystem monitoring
Authors: Toomey Michael , Vierling Lee A
Published: June 2005

Broad-scale monitoring of varying moisture levels of leaves has ramifications for understanding fire potential, biogeochemistry, and ecosystem dynamics. Five different shortwave infrared (SWIR)-derived spectral indices, principal components analysis (PCA), and the tasseled cap transformation (TCT), derived from Landsat Thematic Mapper (TM) and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellite data, were used to quantify landscape-level foliar moisture in an ecosystem dominated by Pinus ponderosa P. & C. Lawson. Landsat TM data demonstrated stronger correlations with in situ calculations of foliar moisture than did ASTER data. The second principal component correlated strongly with ground data (r2 = 0.765). The Landsat-derived TCT wetness component was significantly correlated with ground data (r2 = 0.638) as well as a normalized difference NIR/SWIR ratio (r2 = 0.834). The spectral indices and TCT are more practical for ecosystem moisture monitoring than PCA because of the empirical nature of PCA. Based on these results, we recommend modifications to existing methods of satellite-based fire susceptibility monitoring to account for primary effects of vegetation curing and temporal variation in ground fuels.
High rates of nitrogen fixation of Ulex species in the understory of maritime pine stands and the potential effect of phosphorus fertilization
Authors: Augusto L , Crampon N , Saur E , Bakker M R , Pellerin S , Lavaissière C de , Trichet P
Published: June 2005

Nitrogen (N2) fixation by Ulex species was studied in a range of mature maritime pine (Pinus pinaster Ait.) stands as well as in a phosphorus (P) fertilization trial in a young (6-year-old) open pine stand. The biomass was estimated by allometric relationships, and the percentage of N derived from atmosphere was calculated according to the natural 15N abundance method. Ulex stand biomass was lower in the mature pine stand than in the young open pine stand. In the latter pine stand, Ulex mean annual biomass increment ranged from 1 to 5 Mg·ha1·year1, increasing with P fertilization dose, as did the Ulex stand biomass, ranging from 5.4 to 31.1 Mg·ha1 after six growing seasons in the most highly fertilized treatment. For the sites where the natural 15N abundance method was applicable, the calculated percentage of N in the Ulex europaeus L. tissues derived from atmosphere was very high (mean = 82%; range = 59%100%). At the other sites, the N2 fixation was probably also very important but could not be calculated with confidence. Here, the mean fixation rate of the former sites was used to calculate the N2 fixation flux. The estimated annual N2 fixation flux ranged from 0.5 to 5.1 kg N·ha1·year1 in the mature pine stands. In the young open pine stand, the Ulex understory fixation ranged from 8.1 to 57.4 kg N·ha1·year1, increasing with P fertilization dose. Considering the low levels of N fluxes in theses ecosystems, these figures are very high.
ON BIALGEBRAS ASSOCIATED WITH PATHS AND ESSENTIAL PATHS ON ADE GRAPHS
Authors: COQUEREAUX R. , GARCÍA A. O.
Published: June 2005

We define a graded multiplication on the vector space of essential paths on a graph G (a tree) and show that it is associative. In most interesting applications, this tree is an ADE Dynkin diagram. The vector space of length-preserving endomorphisms of essential paths has a grading obtained from the length of paths and possesses several interesting bialgebra structures. One of these, the Double Triangle Algebra (DTA) of A. Ocneanu, is a particular kind of quantum groupoid (a weak Hopf algebra) and was studied elsewhere; its coproduct gives a filtrated convolution product on the dual vector space. Another bialgebra structure is obtained by replacing this filtered convolution product by a graded associative product. It can be obtained from the former by projection on a subspace of maximal grade, but it is interesting to define it directly, without using the DTA. What is obtained is a weak bialgebra, not a weak Hopf algebra.
WIGNER–ECKART THEOREM FOR TENSOR OPERATORS OF HOPF ALGEBRAS
Authors: MOZRZYMAS MAREK
Published: June 2005

We prove Wigner–Eckart theorem for the irreducible tensor operators for arbitrary Hopf algebras, provided that tensor product of their irreducible representations is completely reducible. The proof is based on the properties of the irreducible representations of Hopf algebras, in particular on Schur lemma. Two classes of tensor operators for the Hopf algebra Ut(su(2)) are considered. The reduced matrix elements for the class of irreducible tensor operators are calculated. A construction of some elements of the center of Ut(su(2)) is given.
Cell-Cycle Control of Gene Expression in Budding and Fission Yeast
Authors: Bähler Jürg
Published: June 2005

Cell-cycle control of transcription seems to be a universal feature of proliferating cells, although relatively little is known about its biological significance and conservation between organisms. The two distantly related yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe have provided valuable complementary insight into the regulation of periodic transcription as a function of the cell cycle. More recently, genome-wide studies of proliferating cells have identified hundreds of periodically expressed genes and underlying mechanisms of transcriptional control. This review discusses the regulation of three major transcriptional waves, which roughly coincide with three main cell-cycle transitions (initiation of DNA replication, entry into mitosis, and exit from mitosis). I also compare and contrast the transcriptional regulatory networks between the two yeasts and discuss the evolutionary conservation and possible roles for cell cycle-regulated transcription.
THE RCS PHOSPHORELAY: A Complex Signal Transduction System
Authors: Majdalani Nadim , Gottesman Susan
Published: June 2005

RcsC, RcsB, and RcsA were first identified as a sensor kinase, a response regulator, and an auxiliary regulatory protein, respectively, regulating the genes of capsular polysaccharide synthesis. Recent advances have demonstrated that these proteins are part of a complex phosphorelay, in which phosphate travels from the histidine kinase domain in RcsC to a response regulator domain in the same protein; from there to a phosphotransfer protein, RcsD; and from there to RcsB. In addition to capsule synthesis, which requires the unstable regulatory protein RcsA, RcsB also stimulates transcription of a small RNA, RprA; the cell division gene ftsZ; and genes encoding membrane and periplasmic proteins, including the osmotically inducible genes osmB and osmC. The Rcs system appears to play an important role in the later stages of biofilm development; induction of Rcs signaling by surfaces is consistent with this role.