bluuebunny/crossref_metadata_2025 huggingface dataset:
Failure of Cilostazol in the Prevention of Ventricular Fibrillation in a Patient with Brugada Syndrome
Authors: ABUD ATILIO , BAGATTIN DANIEL , GOYENECHE RAUL , BECKER CARLOS
Published: September 2005

The ECG appearance in Brugada syndrome is caused by failure of the dome of the action potential to develop. Increased activity of the I(to) current in epicardial cells generates a transmural gradient with repolarization dispersion between the epicardium and the endocardium in the right ventricular wall, thus favoring the development of VF by a phase 2 reentry mechanism. The efficacy of cilostazol for the management of these arrhythmias has been reported. This drug is a phosphodiesterase inhibitor with positive chronotropic properties, thus blocking outward potassium currents I(to) in the myocardial tissue. We present a patient with Brugada syndrome with an implantable cardioverter defibrillator (ICD), who suffered multiple ICD discharges due to VF during therapy with this drug.
Effect of Biventricular Pacing on Left Ventricular Outflow Tract Pressure Gradient in a Patient with Hypertrophic Cardiomyopathy and Normal Interventricular Conduction
Authors: KOMSUOGLU BAKI , VURAL AHMET , AGACDIKEN AYŞEN , URAL DILEK
Published: September 2005

We report a case of hypertrophic obstructive cardiomyopathy (HOCM) that was markedly improved by biventricular pacing. A 55‐year‐old woman with HOCM presented with palpitation and presyncope. Electrophysiologic study revealed an atrioventricular nodal reentrant tachycardia. After radiofrequency catheter ablation, a Mobitz type II atrioventricular block developed and a permanent pacemaker implantation was decided. Cardiac catheterization showed a left ventricular outflow tract (LVOT) gradient of 130 mmHg. Right dual‐chamber and atrial‐synchronous left ventricular epicardial pacing failed to reduce the gradient. After biventricular pacing, LVOT gradient decreased to 20 mmHg. Biventricular pacing may be an alternative therapy for patients with HOCM.
Flutter Localized to the Anterior Left Atrium After Catheter Ablation of Atrial Fibrillation
Authors: JAÏS PIERRE , SANDERS PRASHANTHAN , HSU LI‐FERN , HOCINI MÉLÈZE , SACHER FREDERIC , TAKAHASHI YOSHIHIDE , ROTTER MARTIN , ROSTOCK THOMAS , BORDACHAR PIERRE , REUTER SYLVAIN , LABORDERIE JULIEN , CLÉMENTY JACQUES , HAÏSSAGUERRE MICHEL
Published: September 2005

Introduction: Organized atrial arrhythmias following atrial fibrillation (AF) ablation are typically due to recovered pulmonary vein (PV) conduction or reentry at incomplete ablation lines. We describe the role of nonablated anterior left atrium (LA) in arrhythmias observed after AF ablation.

Methods: A total of 275 consecutive patients with paroxysmal (n = 200) or chronic (n = 75) AF had PV isolation with/without additional linear ablation at the mitral isthmus (n = 106), LA roof (n = 23), or both (n = 88). Organized arrhythmias occurring after ablation were evaluated utilizing activation and entrainment mapping.

Results: Fourteen patients (11 female, 65 ± 13 years, 10 chronic AF, 10 structural heart disease) demonstrated tachycardia localized to the anterior LA, an area not targeted by prior ablation. Eight had ECG features during sinus rhythm suggestive of impaired anterior LA conduction at baseline. These arrhythmias demonstrated a distinctive ECG flutter morphology in 7 of 10 (70%) with discrete −/+ or +/−/+ aspect in inferior leads. Mapping the anterior LA revealed electrograms spanning the entire tachycardia cycle length (325 ± 125 msec). Entrainment was possible in all with a postpacing interval exceeding the tachycardia cycle length by 9 ± 10 msec. Electroanatomic mapping in 6 demonstrated small reentrant circuits rotating clockwise in 4 and counterclockwise in 2. Low‐amplitude, fractionated mid‐diastolic potentials with long duration (200 ± 80 msec) occupying 63 ± 22% of the cycle length were targeted for ablation resulting in termination and subsequent noninducibility.

Conclusion: Organized arrhythmias occurring after AF ablation can be due to reentrant circuits localized to the anterior LA, predominantly in females with chronic AF, structural heart disease, and abnormal atrial conduction. They are characterized by a distinctive surface ECG and highly responsive to RF ablation at the slow conduction area.
Age‐Related Changes in Human Left and Right Atrial Conduction
Authors: KOJODJOJO PIPIN , KANAGARATNAM PRAPA , MARKIDES VIAS , DAVIES D. WYN , PETERS NICHOLAS
Published: September 2005

Introduction: Advancing age is an independent risk factor for atrial fibrillation (AF), which is considered to be initiated by ectopic triggers and maintained by an arrhythmogenic substrate. It is not known whether substrate changes produce this age‐related increase in propensity toward AF. We addressed the hypothesis that advancing age is associated with changes in biatrial electrophysiology even in patients with no history of atrial arrhythmias.

Methods and Results: Patients with left‐sided accessory pathways and requiring routine electrophysiological studies were recruited. Electroanatomic mapping was performed in the left and right atria of 23 patients (age ranging from 17 to 75 years) with structurally normal hearts and no history of AF during sinus rhythm and pacing. Unlike previous studies, a trigonometric method was used to quantify wavefront propagation velocities (WPV) precisely in the direction of propagation. Refractoriness was measured at 2 cycle lengths, at three different atrial sites. Both right (r =−0.77, P < 0.0001) and left (r =−0.79, P < 0.001) atrial WPV demonstrated strongly inverse correlation with age. Furthermore, left and right WPVs were highly correlated (r = 0.66, P < 0.01), with velocities being 6.4 ± 2.2 cm/sec higher in the right atria (P < 0.01). Refractoriness was significantly correlated with increasing age only at the septum (r = 0.53, P < 0.01). Left atrial wavelength was inversely correlated with increasing age (r =−0.56, P = 0.03). P wave duration was associated with age (r = 0.42, P = 0.04) and left atrial size (r = 0.44, P = 0.04) but not atrial WPV.

Conclusion: Aging human atria demonstrate progressive decline in WPV and increase in septal refractoriness. These age‐related changes in biatrial electrophysiology are likely to be important factors in the age‐related increase in AF prevalence.
The effect of maximum bite force on marginal bone loss in mandibular overdenture treatment: an in vivo study
Authors: Van Kampen Frits , Cune Marco , Van Der Bilt Andries , Bosman Frits
Published: September 2005

Abstract: The impact of bite force on the marginal bone response around implants is a subject of debate. This study focused on the effect of maximum bite force on marginal bone levels in mandibular implant overdenture treatment. In addition, the effect of the sequence of 3 different loading conditions on marginal bone loss was evaluated in vivo. The patient population consisted of a group of 18 patients. They received 2 implants in the mandible and a new denture without attachments during the period of submerged implant healing. After second stage surgery, the denture was provided with a ball, magnet or bar‐clip attachment. There was a transition of attachment type after 3 and 6 months of function. The sequence in which the attachments were used was randomised. Radiographic marginal bone loss was measured after the period of submerged implant healing and after 3, 6 and 9 months of functional implant loading. Maximum bite force measurements were obtained just prior to second stage surgery with the new denture without attachment. Bite force measurements were also obtained after 3, 6 and 9 months of loading with the implant‐retained overdenture. The latter 3 values were averaged. The mean bone loss during the period of submerged healing and during functional loading was 1.7 mm (0.7 mm) and 1.3 mm (0.6 mm), respectively. A relationship between maximum bite force during the period of submerged healing or during the period of functional loading on the one hand and the amount of marginal bone loss on the other could not be demonstrated. The sequence in which the different attachment types were used did not influence the observed amount of marginal bone loss.
Human ex vivo bone tissue strains around natural teeth vs. immediate oral implants
Authors: Cehreli Murat Cavit , Akkocaoglu Murat , Comert Ayhan , Tekdemir Ibrahim , Akca Kıvanc
Published: September 2005

Purpose: To compare ex vivo bone tissue strains around natural teeth with immediate implants supporting unsplinted and splinted fixed prostheses.

Material and methods: Six linear strain gauges were bonded on the labial marginal bone of bilateral maxillary anterior teeth in two fresh‐frozen human cadavers. The natural teeth were loaded in centric occlusion via an occlusal splint with integrated miniature load cells. Strain measurements were performed at a sample rate of 10 kHz and under a maximum load of 100 N, simultaneously monitored from a computer connected to data acquisition system. Upon extraction of the anterior teeth, Ø 4.1 mm and Ø 4.8 mm ITI® dental implants were placed into sockets of incisors and canines, respectively. Installation torque value (ITV) of each implant was measured by a custom‐made torque wrench and resonance frequency analyses (RFA) were also undertaken. Strain measurements were performed for (1) single‐tooth implant restorations, (2) unilateral splinted anterior implants, and (3) bilateral splinted anterior implants. Finally, an autopolymerizing acrylic resin was injected into the implant sockets for simulation of osseointegration and strain measurements were performed.

Results: Microstrains of all groups were statistically comparable (P>0.05), although lower strains were elicited for implants in sockets of incisors in comparison with natural teeth. Microstrains around canine implants were comparable or higher than those induced around natural canines. For all groups, microstrains around canines were higher than those around lateral (P<0.05) and central incisors (P<0.01), which had similar strain levels (P>0.05). The RFA values of implants were comparable. The ITVs of implants in sockets of lateral incisors and canines were similar and were higher than those of implants in central incisor regions.

Conclusion: The labial marginal bone having no contact with immediate implants may experience strain gradients within physiologic levels due to deformation of bone under load. Although one prosthetic design does not seem to have clear advantages over another, splinting of implants may be considered as a safety measure for immediately loaded immediate implants, if possible.
Effect of immobilized bone morphogenic protein 2 coating of titanium implants on peri‐implant bone formation
Authors: Schliephake Henning , Aref Arash , Scharnweber Dieter , Bierbaum Susanne , Roessler Sophie , Sewing Andreas
Published: September 2005

Abstract: The aim of the present study was to test the hypothesis that immobilization of bone morphogenic protein (BMP2) on the surface of titanium implants can enhance peri‐implant bone formation. Ten adult female foxhounds received experimental titanium screw implants in the mandible 3 months after removal of all premolar teeth. Three types of implant surfaces were evaluated in each animal: (i) implants with machined titanium surface, (ii) implants coated with collagen I, (iii) implants coated with collagen I, chondroitin sulphate (CS) and BMP2. Peri‐implant bone regeneration was assessed using histomorphometry after 1 and 3 months in five dogs each by measuring bone–implant contact (BIC) and the volume density of the newly formed peri‐implant bone (BVD). After 1 month, there was no significant enhancement in BIC values but volume density of the newly formed peri‐implant bone was significantly higher in the two groups of coated implants. No significant difference was found between collagen and BMP2 coating. After 3 months, BIC was significantly higher in both collagen and BMP2‐coated implants compared with implants with machined surfaces. Peri‐implant BVD was also significantly increased in coated implants in comparison with machined surfaces. It was concluded that collagen coating of dental screw implants can enhance BIC and peri‐implant bone formation. Addition of BMP2 does not increase peri‐implant bone formation in the present application.
Predisposing conditions for retrograde peri‐implantitis, and treatment suggestions
Authors: Quirynen Marc , Vogels Roel , Alsaadi Ghada , Naert Ignace , Jacobs Reinhilde , Steenberghe Daniel van
Published: September 2005

Background: Recent case reports introduced the term retrograde peri‐implantitis as a lesion (radiolucency) around the most apical part of an osseointegrated implant. It develops within the first months after insertion. This retrospective study aimed to find predisposing conditions for such peri‐apical lesions and to evaluate treatment strategies.

Methods: All single implants (426 in the upper, 113 in the lower jaw, all Brånemark system® type) placed at the department of Periodontology of the University Hospital (Catholic University Leuven) were included in this retrospective evaluation to check the incidence of retrograde peri‐implantitis. Eventual predisposing factors such as patient characteristics (age, medical history), recipient site (local bone quality and quantity, cause of tooth loss), periodontal and endodontic conditions of neighboring teeth, implant characteristics (length, surface characteristics), and surgical aspects (guided bone regeneration, osseous fenestration, or dehiscency) were considered. Moreover, implants with retrograde peri‐implantitis were followed longitudinally to verify their treatment outcome by means of different parameters (Periotest® values (PTV), marginal bone level, radiological size of peri‐apical defect).

Results: Seven implants in the upper (1.6%) and 3 in the lower jaw (2.7%) showed retrograde peri‐implantitis, before or at abutment connection. In comparison with successful implants, such peri‐apical lesions occurred preferably at sites with a history of an obvious endodontic pathology of the extracted tooth to be replaced. The incidence of retrograde peri‐implantitis was significantly higher (P<0.0001) for TiUnite® implants when compared with the machined implants (8/80 vs. 2/459). The machined implant surface, however, showed a higher failure rate (6.8%) than the TiUnite® implants (2.5%). Failures with machined surfaces preferably occurred at extraction sites of teeth with a history of endodontic pathology or sites adjacent to teeth with an obvious endodontic pathology. No other predisposing factors could be identified. A curettage of the peri‐apical lesions and the use of a bone substitute material prevented further progression of such lesions in the upper jaw (implants maintained their marginal bone and low PTV scores). A treatment in the lower jaw was less successful.

Conclusions: Within the limitations of a retrospective study, these results seem to indicate that retrograde peri‐implantitis is provoked by remaining scar or granulomatous tissue at the recipient site: endodontic pathology of extracted tooth (scar tissue‐impacted tooth) or possible endodontic pathology from a neighboring tooth.
Influence of three currently used bone replacing materials on the in vitro proliferation of human peripheral blood mononuclear cells
Authors: Wanschitz Felix , Nell Andrea , Patruta Sanda , Wagner Arne , Ewers Rolf
Published: September 2005

Objectives: A cell culture system for biocompatibility testing of bone grafting materials is described. We investigated the in vitro viability and proliferative response of peripheral blood mononuclear cells (PBMC) from 10 healthy donors in the presence of three materials currently used for bone grafting: Algipore, Bio‐Oss and Bone Source, for immunologic biocompatibility testing.

Material and methods: PBMC isolated from venous blood from 10 healthy donors were incubated for 4 days with each bone replacing material, in the presence and absence of interleukin‐2 (IL‐2). After 4 days, H3‐thymidine was added for 18 h and the incorporated radioactivity was measured with a β‐plate counter.

Results: Basal PBMC counts were 152.9±66.2 counts per minute (c.p.m.) (mean±SD), in the presence of 0.4 U IL‐2/well 206.5±83 c.p.m. were measured. With Algipore and Bio‐Oss, which are deproteinized bone replacing materials, the proliferation rate of PBMC with IL‐2 was not significantly modified: for Algipore 151±51 c.p.m./+IL‐2 188.8±62 c.p.m., for Bio‐Oss 144.5±64.9 c.p.m./+IL‐2 176.3±71.23 c.p.m. For Bone Source 164.2±80.4/+IL‐2 188.3±81 c.p.m. were measured.

Conclusion: This in vitro experiment indicates, that the investigated bone replacing materials are not acting as specific antigens/haptens and are not generating increased proliferative responses of human PBMC from healthy donors. Even with IL‐2, that induces proliferation of T lymphocytes, which encountered their specific antigen, the proliferation rate of PBMC from healthy donors was not increased after incubation with this bone grafting materials.
Guided bone regeneration around non‐submerged implants in narrow alveolar ridges: a prospective long‐term clinical study
Authors: De Boever Annemarie L. , De Boever Jan A.
Published: September 2005

Objectives: This prospective clinical study investigates long‐term survival and clinical parameters of non‐submerged implants with large buccal dehiscences treated with a deproteinized bovine bone mineral xenograft and a non‐resorbable membrane in a one‐stage approach.

Material and methods: Sixteen consecutive non‐submerged implants (ITI Straumann) were installed in narrow alveolar ridges in 13 patients (age range: 25–61 years). All patients were non‐smokers. On the buccal site the bone dehiscence ranged between 3 and 9 mm. Primary stability was achieved in all but one implant. The exposed threads were covered with a xenograft (Bio‐Oss®) and a non‐resorbable expanded polytetrafluoroethylene membrane. The flap was sutured leaving the implant head non‐submerged. The membrane was removed when (1) the membrane became exposed or (2) after a maximum of 24 weeks. All implants received singular cemented crowns. The implants were followed for a period ranging from 12 to 114 months. Whole‐mouth plaque index (Pl), the % of bleeding on probing (BOP), probing depth and signs of peri‐implantitis were recorded. Every year periapical radiographs were taken using a long cone technique.

Results: All but one implant integrated successfully. At the time of membrane removal, all previously exposed threads were completely covered with richly vascularized tissue except for two implants where the coverage reached 63% and 87%, respectively. The whole‐mouth plaque score and BOP remained low in all patients during the observation period. None of the implants had plaque and, except for one implant BOP never occurred. All implants were stable and in function. Swelling, redness or purulence was never observed. On the periapical radiographs no bone resorption was observed on the mesial and distal site except for one implant in one patient with a mesial and distal bone resorption of 2 and 3 mm. Probing depth was never higher than 3 mm except for one patient where the implant was placed deeply subgingival for esthetical reasons.

Conclusion: This prospective long‐term study shows that with the use of non‐submerged transmucosal implants, large bony dehiscences can be treated in a one‐stage approach using a stiff non‐resorbable membrane combined with a xenograft.
Effect of magnetic field on the fibronectin adsorption, cell attachment and proliferation on titanium surface
Authors: Kim Hyo Jin , Chang Ik Tae , Heo Seong Joo , Koak Jai Young , Kim Seong Kyun , Jang Jun Hyeog
Published: September 2005

Objectives: We studied the effect of various static magnetic fields (SMFs) on the adsorption of specific recombinant fibronectin (FN) peptide (hFNIII9‐10) on the titanium surface. Furthermore, the responses of human osteosarcoma TE‐85 cells in the SMF were observed.

Material and methods: Various magnetic fields – 1, 2, 3, 5, 7, 10 mT – were established by controlling the distance from Nd–Fe–B magnet to the disks. For FN adsorption experiment, machined titanium disks were incubated in 1 μM hFNIII9‐10 at 37°C overnight under magnetic field. The adsorbed hFNIII9‐10 was measured as optical density (OD). For attachment study, TE‐85 cells were incubated for 2 h on the hFNIII9‐10 coated machined titanium disks and OD values were measured. As for proliferation study, titanium disks were incubated for 48 h after washing unattached cells in 2 h. The amount of proliferated TE‐85 cell was also measured as OD value. Attachments of TE‐85 cells under various intensities of magnetic field were observed using a scanning electron microscope.

Results: The amount of adsorbed hFNIII9‐10 showed no significant difference between control (0 mT) and six experimental groups (1, 2, 3, 5, 7, 10 mT). However, TE‐85 cells attached significantly higher in groups of 1, 2, 5, 10 mT than in control group (P=0). Cell attachment in groups of 3, 7 mT showed no significant difference with that of control group. TE‐85 cells were observed to attach through filopodia. Especially in 1 mT, flattened cells were predominant. In proliferation assay, 1 mT stimulated TE‐85 cells showed significantly higher proliferation than those in 2, 3 and 7 mT (P=0).

Conclusion: Magnetic fields under 10 mT did not influence FN adsorption on the titanium surface. However, a significant effect was found on cell attachment and proliferation.
MITF and cell proliferation: the role of alternative splice forms
Authors: Bismuth Keren , Maric Dragan , Arnheiter Heinz
Published: September 2005

Recent studies show that the melanocyte transcription factor MITF not only activates differentiation genes but also genes involved in the regulation of the cell cycle, suggesting that it provides a link between cell proliferation and differentiation. MITF, however, comes in a variety of splice isoforms with potentially distinct biological activities. In particular, there are two isoforms, (−) and (+) MITF, that differ in six residues located upstream of the DNA binding basic domain and show slight differences in the efficiency with which they bind to target DNA. Using in vitro BrdU incorporation assays and FACS analysis in transiently transfected cells, we show that (+) MITF has a strong inhibitory effect on DNA synthesis while (−) MITF has none or only a mild one. The strong inhibitory activity of (+) MITF is not influenced by a number of mutations that modulate MITF's transcriptional activities and is independent of the protein's carboxyl terminus but dependent on its aminoterminus. A further dissection of the molecule points to the importance of an aminoterminal serine, serine‐73, which in both isoforms is phosphorylated to comparable degrees. The results suggest that one or several aminoterminal domains cooperate with the alternatively spliced hexapeptide to render MITF anti‐proliferative in a way that does not depend on direct E box binding.
OCA4: evidence for a founder effect for the p.D157N mutation of the MATP gene in Japanese and Korean
Authors: Inagaki Katsuhiko , Suzuki Tamio , Ito Shiro , Suzuki Noriyuki , Fukai Kazuyoshi , Horiuchi Toshiyuki , Tanaka Toshihiko , Manabe Etsuko , Tomita Yasushi
Published: September 2005

Oculocutaneous albinism type 4 (OCA4) was identified as a rare form of human OCA among a group of autosomal recessive hypopigmentary disorders. Little is known about the prevailing distribution of patients of OCA4 with mutations of the MATP gene, although one Turkish, five German, one Korean, and 18 Japanese patients have been reported so far. The p.D157N mutation was previously reported to be the most frequent (0.389; 14/36) in Japanese patients and was also found in a Korean patient. On the other hand, this mutation has not been found in Turkish and German patients. We therefore investigated haplotypes of the patients who have the p.D157N mutation. The results showed that OCA4 is prevalent in East Asia including Japan and Korea likely as a result of a founder effect for the p.D157N mutation. Furthermore, it is suspected that the p.D157N mutation might have occurred on an ancestral chromosome after the divergence of Orientals and Caucasians.
Upstream stimulating factors: highly versatile stress‐responsive transcription factors
Authors: Corre Sébastien , Galibert Marie‐Dominique
Published: September 2005

Upstream stimulating factors (USF), USF‐1 and USF‐2, are members of the eucaryotic evolutionary conserved basic‐Helix‐Loop‐Helix‐Leucine Zipper transcription factor family. They interact with high affinity to cognate E‐box regulatory elements (CANNTG), which are largely represented across the whole genome in eucaryotes. The ubiquitously expressed USF‐transcription factors participate in distinct transcriptional processes, mediating recruitment of chromatin remodelling enzymes and interacting with co‐activators and members of the transcription pre‐initiation complex. Results obtained from both cell lines and knock‐out mice indicates that USF factors are key regulators of a wide number of gene regulation networks, including the stress and immune responses, cell cycle and proliferation, lipid and glucid metabolism, and in melanocytes USF‐1 has been implicated as a key UV‐activated regulator of genes associated with pigmentation. This review will focus on general characteristics of the USF‐transcription factors and their place in some regulatory networks.
Different approaches for assaying melanosome transfer
Authors: Berens Werner , Van Den Bossche Karolien , Yoon Tae‐Jin , Westbroek Wendy , Valencia Julio C. , Out Coby J. , Marie Naeyaert Jean , Hearing Vincent J. , Lambert Jo
Published: September 2005

Many approaches have been tried to establish assays for melanosome transfer to keratinocytes. In this report, we describe and summarize various novel attempts to label melanosomes in search of a reliable, specific, reproducible and quantitative assay system. We tried to fluorescently label melanosomes by transfection of GFP‐labeled melanosomal proteins and by incubation of melanocytes with fluorescent melanin intermediates or homologues. In most cases a weak cytoplasmic fluorescence was perceived, which was probably because of incorrect sorting or deficient incorporation of the fluorescent protein and different localization. We were able to label melanosomes via incorporation of 14C‐thiouracil into melanin. Consequently, we tried to develop an assay to separate keratinocytes with transferred radioactivity from melanocytes after co‐culture. Differential trypsinization and different magnetic bead separation techniques were tested with unsatisfactory results. An attempt was also made to incorporate fluorescent thiouracil, since this would allow cells to be separated by FACS. In conclusion, different methods to measure pigment transfer between donor melanocytes and acceptor keratinocytes were thoroughly examined. This information could give other researchers a head start in the search for a melanosome transfer assay with said qualities to better understand pigment transfer.
The signaling pathway in photoresponses that may be mediated by visual pigments in erythrophores of Nile tilapia
Authors: Ban Eiko , Kasai Akiko , Sato Masako , Yokozeki Akemi , Hisatomi Osamu , Oshima Noriko
Published: September 2005

The ability to increase the synthesis or vary the distribution of pigment in response to light is an important feature of many pigment cells. Unlike other light‐sensitive pigment cells, erythrophores of Nile tilapia change the direction of pigment migration depending on the peak wavelength of incident light: light near 365, 400 or 600 nm induces pigment aggregation, while dispersion occurs in response to light at 500 nm. How these phenomena are achieved is currently unknown. In the present study, the phototransduction involved in the pigment dispersion caused by light at 500 nm or the aggregation by light at 600 nm was examined, using pertussis toxin, cholera toxin, blockers of ion channels, various chemicals affecting serial steps of signaling pathways and membrane‐permeable cAMP analog. The results show that light‐induced bidirectional movements in tilapia erythrophores may be controlled by cytosolic cAMP levels via Gi‐ or Gs‐type G proteins. In addition, RT‐PCR demonstrated for the first time the expression of mRNAs encoding red and green opsins in tilapia fins, only where erythrophores exist. Here, we suggest that multiple cone‐type visual pigments may be present in the erythrophores, and that unique cascades in which such opsins couple to Gi or Gs‐type G proteins are involved in the photoresponses in these pigment cells. Thus, tilapia erythrophore system seems to be a nice model for understanding the photoresponses of cells other than visual cells.
The Silver locus product Pmel17/gp100/Silv/ME20: controversial in name and in function
Authors: Theos Alexander C. , Truschel Steven T. , Raposo Graça , Marks Michael S.
Published: September 2005

Mouse coat color mutants have led to the identification of more than 120 genes that encode proteins involved in all aspects of pigmentation, from the regulation of melanocyte development and differentiation to the transcriptional activation of pigment genes, from the enzymatic formation of pigment to the control of melanosome biogenesis and movement [Bennett and Lamoreux (2003)Pigment Cell Res. 16, 333]. One of the more perplexing of the identified mouse pigment genes is encoded at the Silver locus, first identified by Dunn and Thigpen [(1930) J. Heredity21, 495] as responsible for a recessive coat color dilution that worsened with age on black backgrounds. The product of the Silver gene has since been discovered numerous times in different contexts, including the initial search for the tyrosinase gene, the characterization of major melanosome constituents in various species, and the identification of tumor‐associated antigens from melanoma patients. Each discoverer provided a distinct name: Pmel17, gp100, gp95, gp85, ME20, RPE1, SILV and MMP115 among others. Although all its functions are unlikely to have yet been fully described, the protein clearly plays a central role in the biogenesis of the early stages of the pigment organelle, the melanosome, in birds, and mammals. As such, we will refer to the protein in this review simply as pre‐melanosomal protein (Pmel). This review will summarize the structural and functional aspects of Pmel and its role in melanosome biogenesis.
Confined Flow into a Tunnel during Progressive Drilling: An Analytical Solution
Authors: Perrochet Pierre
Published: September 2005

A convolution integral is developed to evaluate transient, drilling speed–dependent discharge rates into a tunnel gradually excavated in a homogeneous infinite aquifer. Comparison with the classical instantaneous‐drilling evaluation commonly used in practice reveals drastically reduced early‐time discharge rates, higher maximum rates, and similar long‐term rates. Dimensionless‐type curves are provided to help assess total discharge sensitivity to drilling time and predict safer maximum flow rates.
Incidence and population dynamics of the leaf beetle Gonioctena olivacea in dynamic habitats
Authors: Biedermann Robert
Published: September 2005

In natural as well as in cultural landscapes, disturbance and succession are responsible for the emergence and subsequent disappearance of suitable habitat patches. The dynamics of habitat patches has important consequences for the spatial structure and dynamics of regional populations. However, there are only few studies quantifying both patch dynamics and incidence of insect species in a dynamic landscape over several years. I studied the incidence and population dynamics of the leaf beetle Gonioctena olivacea in a system of dynamic patches of the host plant Scotch broom Cytisus scoparius. The incidence of the beetle was most strongly affected by patch area, whereas connectivity, patch quality, patch age, and landscape context had no or only a minor effect when analysed with logistic regression. The size of local beetle populations was highly fluctuating between the years; however, the population dynamics of the local populations was not synchronous. Adjacent patches did not show higher degrees of synchrony than patches separated by large distances. In the three years of study, local populations became extinct through demographic or environmental stochasticity and patch destruction. Each year >10% of the patches disappeared. The extinction rate of beetles in persistent patches was decreasing with increasing patch area. On the other hand, patches newly emerged and were rapidly colonized by the beetle. The colonization rate depended on patch connectivity. Obviously, Gonioctena olivacea was capable of persisting in this system with high turnover of patches owing to its high dispersal power.
Spatio‐temporal variation in the pollination mode of Buxus balearica (Buxaceae), an ambophilous and selfing species: mainland‐island comparison
Authors: Lázaro Amparo , Traveset Anna
Published: September 2005

Mixed‐pollination systems may allow plants to achieve stable seed production when unpredictable conditions cause variation in the relative success of different pollination modes. We studied variation in time (two years) and space (in five populations, three from an island and two from mainland) in the pollination mode of Buxus balearica, an ambophilous (i.e. pollinated by wind and insects) and selfing species distributed in the Mediterranean Basin, by means of direct observations and experimental manipulations (bagging with different material). The relative importance of each pollination mode differed among populations; however, levels of selfing and wind pollination were similar between island and mainland. Flowers of B. balearica were visited only by generalist insects, and species composition and abundance of flower visitors varied both in space and time. Frequency of insect visits to plants were not higher in mainland than island populations, although insects on the mainland were more diverse, visited a proportionally greater number of flowers, and remained longer on the plants than insects on the island. Frequency of insect visits was negatively correlated with flowering synchrony (all populations pooled) and was found to increase seed set in one of the mainland populations (that with highest frequency of insect visits and highest flower visitation rate). Fruit and seed mass were found to be not affected by pollination mode. Scarcity of pollinators in the island seems to have an effect on the pollination mode, although the greatest variation in breeding system was found at a more local scale.
Long‐term consequences of the alteration of the seed dispersal process of Euphorbia characias due to the Argentine ant invasion
Authors: Oliveras Jordi , Bas Josep M. , Gómez Crisanto
Published: September 2005

The alteration of the seed dispersal process due to the Argentine ant invasion and its consequences on emergence, recruitment, distribution, and survival of seedlings of Euphorbia characias were analyzed. The study was carried out in two zones of Mediterranean cork‐oak secondary forest, one invaded by L. humile and the other non‐invaded. Two cohorts of E. characias seedlings (those emerged in 2001 and those emerged in 2002) were studied in three study plots in each zone. The level of seed loss due to lack of viability, parasitizing, and vertebrate predation did not differ between the two zones. The mean seed sowing depth was lower in the invaded zone (13.5 mm) than in the non‐invaded zone (22.4 mm). This depth difference implies a longer time needed for seedlings to emerge in the non‐invaded zone but not a different emergence percent under laboratory conditions. In the field study plots seedling recruitment did not differ between the two zones, probably due to the trade‐off between the differences in the initial number of seeds released (higher in the non‐invaded zone) and the different emergence proportions (higher in the invaded zone). As for the spatial characteristics of emerged seedlings, no differences in the mean seedling distance to the nearest inflorescence or to the nearest seedling or in the pattern of seedling distribution were found between zones. Seedling survival was assessed once a month until they had reached maturity or until all of them had died. The median seedling survival time was similar between the invaded and the non‐invaded zones. Survival curves also did not differ between zones. The present study suggests a functional equivalence of the Argentine ant after the replacement of the native ant species. Despite the initial differences found, the final reproductive success of E. characias was not altered after the invasion. However, the case of E. characias seems unlikely to be the rule, and the seed dynamics of other species may be altered, i.e. increased or decreased, and thus positively or negatively affected by the invasion.
Experiments on the Interaction of Light and Sound for the Advanced Laboratory
Authors: Pierce D. T. , Byer R. L.
Published: September 2005

We describe an advanced laboratory experiment in which both Raman-Nath and Bragg diffraction of light by acoustic waves in water are observed in the sound frequency range from 5 to 45 MHz. The apparatus consists of a laser, light detector, rf power source, quartz transducer, and homemade water cell. We discuss the theory of Raman-Nath diffraction, Bragg diffraction, and the criteria for the manifestation of each. The measured Raman-Nath diffracted orders give a visual display of FM sidebands. We discuss a quantitative relationship between the incident and diffracted light and the sound for Bragg diffraction in terms of a three-wave parametric process. Stanford students in the Advanced Applied Physics Laboratory have successfully performed this experiment during the past three years.
A Note on the Morphology of Heat Capacity Curves
Authors: Meijer Paul H. E. , Colwell Jack H. , Shah B. P.
Published: September 2005

In this article we try to relate the general features of several types of heat capacity curves to the underlying energy level spectrum. We are interested in heat capacity “anomalies” (i.e., heat capacities which occur in addition to the usual lattice vibration and conduction electron contributions) and restrict ourselves to systems which can be described on an independent particle basis. We begin by considering Schottky anomalies and show the effects on the heat capacity of varying the spacings and degeneracies of the energy levels. The relation between the Schottky anomaly arising from the equally spaced nondegenerate levels of the Brillouin function and the heat capacity of the Einstein function is discussed. The effects on the heat capacity of a marked local change in the density of states of an otherwise uniform energy-level spectrum is considered. The heat capacities of the free rotor and the molecular field model are used to exemplify particular points of the discussion.
The Nature of Things—A Survey Course in Modern Physics
Authors: Gleeson A. M.
Published: September 2005

This paper is a report on the development of a survey course in modern physics for upper division liberal arts students. This course emphasizes the conceptual and philosophical basis of modern physics. The method of teaching leans heavily on modern visual aids and lecture demonstrations.
Energy Conservation and WKB Methods
Authors: Waterman P. C.
Published: September 2005

Upon invoking energy considerations, the wavefunction in a variable medium is found rigorously to have the form u(x) = g−1/2 exp[i∫x(g+i Imε/2g)dx], in which ε(x) is the square of the complex index of refraction (or the appropriate function of the quantum-mechanical potential), and g(x) is a real function satisfying a second-order non-linear differential equation. Approximate solutions are obtained for g(x) either by iteration or numerical integration; the resulting wavefunctions satisfy energy constraints exactly. Addition formulas and general connection formulas are derived, and field behavior is examined for classical turning points, reflection by barriers, and bound states, using closed-form examples.
Identification of Radioactive Isotopes in Reactor Pool Water
Authors: Mancuso R. V. , Ulinski J. A.
Published: September 2005

A lithium-drifted germanium detector has been used to identify 36 radioactive isotopes in a sample of pool water from the Western New York Research Center reactor. A total of 100 peaks were observed in gamma-ray spectra taken over a period of 3 months. The primary methods of production of the isotopes are fission and the (n, γ) reaction. Two isotopes were produced by the (n, p) reaction and possibly one by the (p, n) reaction. Fission products are present in the water as a result of a fuel element cladding failure. The elements which were activated are either in the water as a result of corrosion of material in the pool, or in water soluble compounds of elements from material in the pool.
“Gibbs Paradox” Paradox
Authors: Casper Barry M. , Freier Susan
Published: September 2005

The traditional resolution of Gibbs paradox seems to give rise to a further paradox. A resolution of this paradox is proposed.
Classical Limit of the Hydrogen Atom
Authors: Brown Lowell S.
Published: September 2005

A wavepacket solution for the hydrogen atom in the region of large principal quantum number n is constructed. This wavepacket follows a classical circular orbit. It has a width on the order of n−1/2 times the size of the orbit.
Classroom Demonstration of the Laws of Propagation of Gaussian Beams
Authors: Arnaud J. A.
Published: September 2005

A method for simulating the propagation of coherent optical beams with Gaussian irradiance patterns in free space and through unaberrated lenses is described. This method is based on the skew-ray representation of Gaussian beams. The rotation in space of a collimated laser beam with skew axis generates a Gaussian beam profile. The phase of the optical field is given by the angular position of the laser-beam center.
Digital Electronics in the Elementary Laboratory
Authors: Jones S. T. , Alexander C.
Published: September 2005

We describe a series of simple experiments which introduce beginning physics students to simple circuits and solid state devices. The circuits demonstrate interesting digital applications of diodes and transistors, as well as providing an aid to the understanding of the concepts of voltage and current.
The Analog Computer as a Teaching Tool in Physics
Authors: Wylen H. E. , Schwarz W. M.
Published: September 2005

A number of experiments which utilize small desktop analog computers (e.g., the EAI Model TR-20) and which are appropriate for an upper level physics laboratory are described. The computer is used in some experiments to simulate the physical system under investigation and in other experiments as an on-line device which aids the analysis of the physical system itself. Experiments of both types have been used successfully for several years in the electricity and magnetism and modern physics laboratories at Union College. Students have received this technique enthusiastically and have gained knowledge not only of the experiments involved but of the analog computer and its components as well. Projects of this type can be implemented in any of the upper level laboratories even without the use of commercial analog computers since many of the experiments can be performed with home-made devices consisting of low-cost operational amplifiers, capacitors, rheostats, and other standard laboratory equipment.
An Experiment on Electron Interference
Authors: Donati O. , Missiroli G. P. , Pozzi G.
Published: September 2005

An electron interference experiment that provides impressive evidence of the wave-like behavior of electrons has been performed. The interferometric device has been designed as simply as possible and is described in detail. A standard electron microscope is used as an electron-optical bench.
Young's Modulus Determination Via Simple, Inexpensive Static and Dynamic Measurements
Authors: Wilson Frederick , Lord A. E.
Published: September 2005

An extremely inexpensive, simple, dynamic modulus apparatus has been developed. The apparatus uses the various bending vibration resonances to determine Young's modulus. The moduli values for steel and balsa wood compare very favorably with the values obtained via static bending measurements and those obtained from the literature. The apparatus can be built for about ten dollars if an audio generator, an audio amplifier, and an oscilloscope are available.
Thermal Conductivity and Anharmonic Forces
Authors: Black M. A.
Published: September 2005

A common model of a solid assumes a regular lattice of atoms which interact via perfectly harmonic forces. Although this model can explain many properties of solids, it is unable to explain why the thermal conductivity of dielectric crystals is not infinite. The source of the problem lies in the slightly anharmonic nature of the forces involved. The following article describes a simple model which allows the effect of the anharmonic forces to be calculated and the thermal conductivity estimated. The results are in agreement with other methods of calculation.
Elementary Use of Spheroidal Coordinates
Authors: Andrews C. L. , Margolis D. P.
Published: September 2005

We recommend the use of the spheroidal coordinate systems in undergraduate physics. To illustrate the importance of choosing a convenient coordinate system we solve some problems in electrostatics. A glance at the calculus table of elementary differentials suggests that the arctangent, arccotangent, archyperbolic tangent, and archyperbolic cotangent will each satisfy one of the two Laplace's equations in the spheroidal coordinate systems. Limiting cases of a series of solutions are given that correspond to useful configurations in electrical technology.
Toward Wider Public Understanding of Science
Authors: Arons Arnold
Published: September 2005

Wider understanding of science will be achieved only by giving students a chance to synthesize experience and thought into knowledge and understanding. Such a chance is not available in the deluge of unintelligible names and jargon precipitated at unmanageable pace and volume in so large a proportion of our college courses, and it is not available in the absence of humanistic, historical, or philosophical perspectives within these courses. Neither will salvation be found in topical courses on currently “popular” matters such as the energy crisis, environmental problems, or societal impact—so long as these problems are plunged into without any genuine prior understanding of the underlying scientific ideas. Some deeply valuable lessons about the learning process, as it occurs in all individuals, are to be learned from among the best of the new elementary science curricula that are now available to the schools. These lessons are transferable to college level and might help us simultaneously develop a new generation of teachers who would begin to disseminate a wider public understanding of science through competent teaching of science in the elementary schools.
Scattering of Charged Particles by a Localized Magnetic Field
Authors: Lapidus I. Richard
Published: September 2005

The classical differential and total cross sections for scattering of charged particles by a uniform magnetic field localized in a cylindrical region of space are computed using a two-dimensional analogue of the usual definition of scattering cross section.
The Electrocardiogram as an Example of Electrostatics
Authors: Hobbie Russell K.
Published: September 2005

The relationship of the electrocardiogram (EKG) to the charge distribution in the heart provides an interesting example of electrostatics for a general physics course. The qualitative features of the EKG can be explained by a simple electrostatic model which ignores the electrical conconductivity of the body. This model is developed and used to explain some EKG patterns.