bluuebunny/crossref_metadata_2025 huggingface dataset:
Late‐Life Anemia Is Associated with Increased Risk of Recurrent Falls
Authors: Penninx Brenda W. J. H. , Pluijm Saskia M. F. , Lips Paul , Woodman Richard , Miedema Kor , Guralnik Jack M. , Deeg Dorly J. H.
Published: October 2005

Objectives: To examine whether anemia is associated with a higher incidence of recurrent falls.

Design: Prospective cohort study.

Setting: Community‐dwelling sample in the Netherlands.

Participants: Three hundred ninety‐four participants aged 65 to 88 from the Longitudinal Aging Study Amsterdam.

measurements: Anemia was defined according to World Health Organization criteria as a hemoglobin concentration less than 12 g/dL in women and less than 13 g/dL in men. Falls were prospectively determined using fall calendars that participants filled out weekly for 3 years. Recurrent fallers were identified as those who fell at least two times within 6 months during the 3‐year follow‐up.

Results: Of the 394 persons, 11.9% (18 women and 29 men) had anemia. The incidence of recurrent falls was 38.3% of anemic persons versus 19.6% of nonanemic persons (P=.004). After adjustment for sex, age, body mass index, and diseases, anemia was significantly associated with a 1.91 times greater risk for recurrent falls (95% confidence interval=1.09–3.36). Poor physical function (indicated by muscle strength, physical performance, and limitations) partly mediated the association between anemia and incidence of recurrent falls.

Conclusion: Late‐life anemia is common and associated with twice the risk of recurrent falls. Muscle weakness and poor physical performance appear to partly mediate this association.
A Model of Middle–Level Managers’ Entrepreneurial Behavior
Authors: Kuratko Donald F. , Ireland R. Duane , Covin Jeffrey G. , Hornsby Jeffrey S.
Published: October 2005

Middle–level managers’ entrepreneurial behavior is linked to successful corporate entrepreneurship. Herein, we integrate knowledge about corporate entrepreneurship and middle–level managers’ behaviors to develop and explore a conceptual model. The model depicts the organizational antecedents of middle–level managers’ entrepreneurial behavior, the entrepreneurial actions describing that behavior, and outcomes of that behavior as well as factors influencing its continuance. Following discussion of the model's contents, we describe its potential value for researchers and those engaging in corporate entrepreneurship.
All Credit to Men? Entrepreneurship, Finance, and Gender
Authors: Marlow Susan , Patton Dean
Published: October 2005

Availability of, and access to finance is a critical element to the start–up and consequent performance of any enterprise. Hence, any barriers or impediments to accessing appropriate levels or sources of funding will have an enduring and negative impact upon the performance of affected firms. Although findings have been somewhat inconsistent, there is support for the notion that women entrepreneurs entering self–employment are disadvantaged by their gender. This argument is evaluated through a theoretical analysis of gender using the example of accessing both formal and informal sources of business funding to illustrate how this concept impacts upon women in self–employment.
Interatrial Electrical Connections: The Precise Location and Preferential Conduction
Authors: SAKAMOTO SHUN‐ICHIRO , NITTA TAKASHI , ISHII YOSUKE , MIYAGI YASUO , OHMORI HIROYA , SHIMIZU KAZUO
Published: September 2005

Background: The atria are assumed to be connected electrically to each other at the level of the Bachmann's bundle, coronary sinus (CS) musculature, and interatrial septum, and these connections may have an important role in the interatrial conduction and perpetuation of various types of atrial tachyarrhythmias. However, the number, location, and preferential connections of the interatrial conduction related to the site of activation have not been examined yet.

Methods: The endocardium of both atria and the CS were mapped during continuous pacing from the left superior and inferior pulmonary veins, right pulmonary veins, upper and lower right atrium, or right atrial septum at various paced cycle lengths in 14 canines. The electrograms were recorded by custom‐made form‐fitted electrodes mounted on a specially designed device that allowed the septal aspects of the electrode forms to be spatially fixed to each other accurately.

Results: Four distinct interatrial electrical connections were identified at the Bachmann's bundle, CS, and antero‐superior and postero‐inferior septa. Decremental conduction was not seen in any of the connections. Bachmann's bundle was the most preferential connection during pacing from any epicardial site. The transseptal connections were evident only during pacing from the interatrial septum. The preference among the four connections was determined by the site of stimulation and the propagation of the activation related to the myocardial architecture.

Conclusion: These unique preferential connections may play a significant role in the interatrial conduction and perpetuation of atrial tachyarrhythmias.
Validation of ECG Indices of Ventricular Repolarization Heterogeneity: A Computer Simulation Study
Authors: VAN HUYSDUYNEN BART HOOFT , SWENNE CEES A. , DRAISMA HARMEN H.M. , ANTONI M. LOUISA , VAN DE VOOREN HEDDE , VAN DER WALL ERNST E. , SCHALIJ MARTIN J.
Published: September 2005

Introduction: Repolarization heterogeneity (RH) is functionally linked to dispersion in refractoriness and to arrhythmogenicity. In the current study, we validate several proposed electrocardiogram (ECG) indices for RH: T‐wave amplitude, ‐area, ‐complexity, and ‐symmetry ratio, QT dispersion, and the Tapex‐end interval (the latter being an index of transmural dispersion of the repolarization (TDR)).

Methods and Results: We used ECGSIM, a mathematical simulation model of ECG genesis in a human thorax, and varied global RH by increasing the standard deviation (SD) of the repolarization instants from 20 (default) to 70 msec in steps of 10 msec. T‐wave amplitude, ‐area, ‐symmetry, and Tapex‐end depended linearly on SD. T‐wave amplitude increased from 275 ± 173 to 881 ± 456 μV, T‐wave area from 34 × 103± 21 × 103 to 141 × 103± 58 × 103μV msec, T‐wave symmetry decreased from 1.55 ± 0.11 to 1.06 ± 0.23, and Tapex‐end increased from 84 ± 17 to 171 ± 52 msec. T‐wave complexity increased initially but saturated at SD = 50 msec. QT dispersion increased modestly until SD = 40 msec and more rapidly for higher values of SD. TDR increased linearly with SD. Tapex‐end increased linearly with TDR, but overestimated it.

Conclusion: T‐wave complexity did not discriminate between differences in larger RH values. QT dispersion had low sensitivity in the transitional zone between normal and abnormal RH. In conclusion, T‐wave amplitude, ‐area, ‐symmetry, and, with some limitations, Tapex‐end and T‐wave complexity reliably reflect changes in RH.
Chronic Hemodynamic Effects After Radiofrequency Catheter Ablation of Frequent Monomorphic Ventricular Premature Beats
Authors: SEKIGUCHI YUKIO , AONUMA KAZUTAKA , YAMAUCHI YASUTERU , OBAYASHI TOHRU , NIWA AKIHIRO , HACHIYA HITOSHI , TAKAHASHI ATSUSHI , NITTA JUNICHI , IESAKA YOSHITO , ISOBE MITSUAKI
Published: September 2005

Introduction: Radiofrequency catheter ablation (RFCA) of severely symptomatic monomorphic ventricular premature beats (VPBs) is reported to be a safe and effective treatment option. However, the chronic hemodynamic effects of these VPBs have not been precisely evaluated.

Methods and Results: We sought to investigate chronic effects after decreasing the number of VPBs by RFCA. A total of 47 patients who had no underlying heart disease and frequent monomorphic VPBs, consisting of more than 10,000 beats per day (24,194 ± 12,516 beats per day), were enrolled. Patients were treated with RFCA and followed up over 6 months as outpatients. Echocardiography and serum B‐type natriuretic peptide (BNP) level were repeatedly checked before and after RFCA. In 38 patients, whose VPBs were dramatically decreased to less than 1,000 beats per day by successful RFCA, left ventricular (LV) end‐diastolic dimension (LVEDd) and end‐systolic dimension (LVESd) measured by echocardiography decreased significantly (LVEDd: 50 ± 5 to 48 ± 5 mm, P < 0.01; LVESd: 33 ± 7 to 30 ± 6 mm, P < 0.01) in association with improvement of BNP level (39.9 ± 34.1 to 16.8 ± 10.3 pg/mL, P = 0.0001). In nine patients, whose VPBs were treated unsuccessfully by RFCA or that recurred, LV dimensions and BNP level did not change during the follow‐up period.

Conclusion: Significant improvement in LV dimensions and serum BNP level appeared to indicate that RFCA of VPBs ameliorated occult cardiac dysfunction induced by frequent VPBs.
Electrocardiographic Characteristics of Repetitive Monomorphic Right Ventricular Tachycardia Originating Near the His‐Bundle
Authors: YAMAUCHI YASUTERU , AONUMA KAZUTAKA , TAKAHASHI ATSUSHI , SEKIGUCHI YUKIO , HACHIYA HITOSHI , YOKOYAMA YASUHIRO , KUMAGAI KOJI , NOGAMI AKIHIKO , IESAKA YOSHITO , ISOBE MITSUAKI
Published: September 2005

Introduction: Most idiopathic nonreentrant ventricular tachycardia (VT) and ventricular premature contractions (VPCs) arise from the right or left ventricular outflow tract (OT). However, some right ventricular (RV) VT/VPCs originate near the His‐bundle region. The aim of this study was to investigate ECG characteristics of VT/VPCs originating near the His‐bundle in comparison with right ventricular outflow tract (RVOT)‐VT/VPCs.

Methods and Results: Ninety RV‐VT/VPC patients underwent catheter mapping and radiofrequency ablation. ECG variables were compared between VT/VPCs originating from the RVOT and near the His‐bundle. Ten patients had foci near the His‐bundle (HIS group), with the His‐bundle local ventricular electrogram preceding the QRS onset by 15–35 msec (mean: 22 msec) and His‐bundle pacing produced a nearly identical ECG to clinical VT/VPCs. The HIS group R wave amplitude in the inferior leads (lead III: 1.0 ± 0.6 mV) was significantly lower than that of the RVOT group (1.7 ± 0.4 mV, P < 0.05). An R wave in aVL was present in 6 of 10 HIS group patients, while almost all RVOT group patients had a QS pattern in aVL. Lead I in HIS group exhibited significantly taller R wave amplitudes than RVOT group. HIS group QRS duration in the inferior leads was shorter than that of the RVOT group. Eight of 10 HIS group patients exhibited a QS pattern in lead V1 compared to 14 of 81 RVOT group patients. HIS group had larger R wave amplitudes in leads V5 and V6 than RVOT group.

Conclusion: VT/VPCs originating near the His‐bundle have distinctive ECG characteristics. Knowledge of the characteristic QRS morphology may facilitate catheter mapping and successful ablation.
Modification of Ventricular Fibrillation Activation Patterns Induced by Local Stretching
Authors: CHORRO FRANCISCO J. , TRAPERO ISABEL , GUERRERO JUAN , SUCH LUIS M. , CANOVES JOAQUÍN , MAINAR LUIS , FERRERO ANGEL , BLASCO ESTRELLA , SANCHIS JUAN , MILLET JOSÉ , TORMOS ÁLVARO , BODÍ VICENTE , ALBEROLA ANTONIO
Published: September 2005

Introduction: We hypothesize that local modifications in electrophysiological properties, when confined to zones of limited extent, induce few changes in the global activation process during ventricular fibrillation (VF). To test this hypothesis, we produced local electrophysiological modifications by stretching a circumscribed zone of the left ventricular wall in an experimental model of VF.

Methods and Results: In 23 Langendorff‐perfused rabbit hearts frequency, time–frequency and time‐domain techniques were used to analyze the VF recordings obtained with two epicardial multiple electrodes before, during, and after local stretching produced with a left intraventricular device. Acute local stretching accelerated VF in the stretched zone reversibly and to a variable degree, depending on the magnitude of stretch and the time elapsed from its application. In the half time (5 minutes) of the analyzed period, a longitudinal lengthening of 12.1 ± 4.5% (vertical axis) and 11.8 ± 6.2% (horizontal axis) in the stretched zone produced an increase in the dominant frequency (DFr) (15.2 ± 1.9 versus 18.8 ± 2.5 Hz, P < 0.0001), a decrease in mean VV interval (63 ± 8 versus 53 ± 6 msec, P < 0.001), and an increase in the complexity of the activation maps—with more areas of conduction block and more breakthrough patterns (23% versus 37%, P < 0.01), without significant changes in the percentages of complete reentry patterns (9% versus 9%, ns). Simultaneously, in the nonstretched zone, no variations were observed in the DFr (15.2 ± 2.1 versus 15.3 ± 2.5 Hz, ns), mean VV intervals (66 ± 8 versus 65 ± 8 msec, ns), or types and percentages of maps with breakthrough (25% versus 20%, ns) or reentry patterns (12% versus 8%, ns). No significant correlation was observed between the DFr in the two zones (R = 0.24, P = 0.40).

Conclusion: Local stretching increases the electrophysiological heterogeneity of myocardium and accelerates and increases the complexity of VF in the stretched area, without significantly modifying the occurrences of the types of VF activation patterns in the nonstretched zone.
Determinants of Recurrent Ventricular Arrhythmia or Death in 300 Consecutive Patients with Ischemic Heart Disease Who Experienced Aborted Sudden Death: Data from the Leiden Out‐of‐Hospital Cardiac Arrest Study
Authors: KIÈS PHILIPPINE , BOERSMA ERIC , BAX JEROEN J. , Van Der BURG ALIDA E. BORGER , BOOTSMA MARIANNE , Van ERVEN LIESELOT , Van Der WALL ERNST E. , SCHALIJ MARTIN J.
Published: September 2005

Objective: Evaluation of the relation between clinical characteristics and incidence of recurrent ventricular arrhythmias (VAs) or death during long‐term follow‐up in a cohort of 300 consecutive ischemic heart disease (IHD) patients who had survived an episode of sudden cardiac arrest (SCA).

Background: Survivors of life‐threatening VA are at high risk for recurrent events.

Methods: A total of 300 consecutive survivors of SCA with IHD were included in a standardized screening and evaluation protocol. Multivariable Cox regression analysis was performed to determine the relation between clinical variables at baseline and the incidence of recurrent VA, all‐cause mortality and the composite of both (composite endpoint).

Results: The presenting arrhythmia was VT in 156 (52%) patients and VF in 144 (48%) patients. Revascularization was performed in 78 (26%) patients and an ICD was implanted in 216 (72%) patients. During follow‐up (mean 30 ± 21 months) 37 (12%) patients died and 88 (29%) patients experienced a recurrence. Advanced age (adjusted hazard ratio (HR) 2.0; 1.2–3.3), history of heart failure (HR 1.8; 1.2–2.6), and amiodarone use (HR 3.1; 2.1–4.6) were independent predictors for the composite endpoint. VT as presenting arrhythmia was an independent predictor for all‐cause mortality only (HR 2.4; 1.2–4.8). A decreased risk of recurrences was determined by beta‐blocker use (HR 0.5; 0.4–0.8) and coronary revascularization (HR 0.3; 0.2–0.6).

Conclusion: In a cohort of 300 consecutive survivors of SCA the incidence of recurrent VA and death is dependant on patient age, history of heart failure, and use of amiodarone. In contrast, use of beta‐blockers and aggressive coronary revascularization improve the outcome.
Wave Similarity Mapping Shows the Spatiotemporal Distribution of Fibrillatory Wave Complexity in the Human Right Atrium During Paroxysmal and Chronic Atrial Fibrillation
Authors: RAVELLI FLAVIA , FAES LUCA , SANDRINI LUCA , GAITA FIORENZO , ANTOLINI RENZO , SCAGLIONE MARCO , NOLLO GIANDOMENICO
Published: September 2005

Introduction: The complexity of waveforms during atrial fibrillation may reflect critical activation patterns for the arrhythmia perpetuation. In this study, we introduce a novel concept of map, based on the analysis of the wave morphology, which gives a direct evidence in the human right atrium on the spatiotemporal distribution of fibrillatory wave complexity in paroxysmal (PAF) and chronic (CAF) atrial fibrillation.

Methods and Results: Electrograms were recorded from a 64‐electrode catheter in the right atrium of 15 patients during PAF (n = 8) and CAF (n = 7). Wave similarity maps were constructed by calculating the degree of morphological similarity of activation waves (S) at each atrial site and by following its temporal evolution. During PAF the spatiotemporal distribution of the waveforms was highly consistent across the subjects and was determined by the anatomic location. Wave similarity maps showed the existence of an extended area with low similarity index, which covered the low posteroseptal atrium (S = 0.28 ± 0.09) and the septal region (S = 0.22 ± 0.04), and the presence of a large tongue with high similarity index, which penetrated the lateral wall (S = 0.55 ± 0.08) starting from the high anterolateral atrium (S = 0.54 ± 0.06). A completely different spatiotemporal pattern was seen during CAF. No distinct regions with different similarity indexes were recognized, but a uniformly distributed low similarity index (S = 0.27 ± 0.07) was found. The spatial pattern was highly stable in time with fluctuations of S < 0.04.

Conclusion: Quantification of the spatiotemporal distribution of fibrillatory wave complexity is feasible in humans by wave similarity mapping. Anatomic anchoring of waveforms during PAF and pattern destruction during CAF was determined.
Transvenous Cryoablation Reduces Platelet Activation During Pulmonary Vein Ablation Compared with Radiofrequency Energy in Patients with Atrial Fibrillation
Authors: TSE HUNG‐FAT , KWONG YOK‐LAM , LAU CHU‐PAK
Published: September 2005

Background: Radiofrequency (RF) ablation procedures for atrial fibrillation (AF) are associated with potential risks of thromboembolism, which may be minimized by the use of cryoablation that preserves the integrity of endocardium. The objective of this study was to compare the thrombogenic potential of transvenous cryoablation versus RF ablation during pulmonary vein (PV) isolation.

Methods and Results: Thirty consecutive patients with paroxysmal AF were randomized to undergo segmental PV isolation procedure using 4‐mm tip RF ablation (n = 15) or cryoablation (CryoCor, San Diego, CA, USA) (n = 15). Blood samples were drawn after sheath insertion (baseline), after transseptal puncture, before ablation (after heparin administration), and after isolation of a superior PV. Activation of coagulation was measured with plasma levels of prothrombin fragment 1 + 2 (F1 + 2) and thrombin‐antithrombin III complex (TAT), and platelets by plasma level of β‐thromboglobulin (β‐TG) and flow cytometric enumerating of P‐selectin (CD62)‐positive platelets. In both groups, the plasma level of β‐TG, F1 + 2, and TAT were elevated after sheath insertion. The percentage changes in plasma level of β‐TG, F1 + 2, and TAT and CD41/62‐positive platelets from baseline after transseptal puncture and before ablation were similar (P > 0.05). However, the percentage changes in CD62‐positive platelets from baseline were significantly higher in patients treated with RF ablation (82 ± 20%) than with cryoablation (22 ± 14%, P = 0.02), although their plasma levels of β‐TG, F1 + 2, and TAT were not different (P > 0.05).

Conclusions: Significant platelet and coagulation activations were observed during PV ablation procedures, and heparin administration only prevented activation of coagulation but not platelets. Persistent platelets activation was observed during RF energy application, but not during cryoablation.
Relationship between bleeding on probing and periodontal disease progression in community‐dwelling older adults
Authors: Rahardjo A. , Yoshihara A. , Amarasena N. , Ogawa H. , Nakashima K. , Miyazaki H.
Published: October 2005

Objective: The main objective of this study was to determine the relationship between bleeding on probing (BOP) and periodontal disease progression in community‐dwelling older adults.

Methods: A 3‐year longitudinal study was carried out in 229 non‐smoking healthy older adults aged 70 years. Using pressure‐controlled periodontal probes, BOP, pocket depth and attachment level at 13,289 sites were measured annually. Periodontal disease progression was defined as an increase in attachment loss of 3 mm from the baseline to the final examination. The backward stepwise logistic regression analysis was performed to assess the relationship between the total number of sites with BOP in the four examinations and periodontal progression.

Results: Logistic regression analysis showed that the odds ratios of BOP frequency for periodontal disease progression ranged from 1.4 to 6.2 after controlling for pocket depth 4 mm at baseline, number of missing teeth, jaw type and tooth site.

Conclusion: Increasing frequencies of bleeding might increase the probability of periodontal disease progression in community‐dwelling older adults.
Students’ perceived experience of university admission based on tests and interviews
Authors: Röding K. , Nordenram G.
Published: September 2005

The aim of the study was to generate an impression, from the perspective of graduating dental students, of the individualised admissions procedures, which they had undergone 5 years before. The subjects comprised 10 randomly selected students, five male and five female, from two different admission rounds. Qualitative research was used and data were collected by means of semi‐structured interviews. The results show that even 5 years later, the students remember clearly the different steps in the selection procedure and they found the procedure relevant. In particular, the admission interviews made a lasting impression. The students consider that being interviewed by one admissions committee member at a time reduces the applicant's apprehension and allows a more personal interview. Several believe that the admissions procedure influences academic achievement or improves self‐confidence: implicit in their selection by a committee of experienced professionals is affirmation that they have the potential to become good dentists. The students therefore feel encouraged to aspire to higher achievement. All students believe that motivation is an important non‐cognitive attribute for success and that students selected through this mode are not only highly motivated but also well informed, with realistic expectations of the undergraduate programme and their future professional career.
The influence of context on students’ approaches to learning: a case study
Authors: Kieser J. , Herbison P. , Harland T.
Published: September 2005

This paper gives an account of a small‐scale longitudinal study that examined changes in conceptions and approaches to learning as 14 students experience a problem‐based learning (PBL) curriculum for the first time. The course in oral biology aimed to encourage conceptual understanding of the topic and improve student learning through its PBL curriculum and assessment method. Those who entered the course with a surface approach and fragmented conception of learning left with a deep‐learning approach, cohesive conception and quality learning outcomes. There were no observable changes in the students who started the course with a deep‐learning approach and cohesive conception, except for two who reported surface approaches and fragmented conceptions at the end. These two students also achieved the lowest examination scores. To help explain these findings we examine the wider context for student learning including student motivation.
Oral self‐care behaviours: comparing Greek and Japanese dental students
Authors: Polychronopoulou Argy , Kawamura Makoto
Published: September 2005

Aim:  This study explored cross‐cultural differences of self‐reported oral health behaviours between Greek and Japanese dental students.

Participants:  The sample population included 877 dental students, 539 students registered at the University of Athens Dental School, and 338 registered at the Hiroshima University Dental School.

Material and methods:  Oral health behaviour was assessed using the Greek and Japanese versions of a 20‐item questionnaire entitled Hiroshima University‐Dental Behavioural Inventory (HU‐DBI).

Results:  The mean questionnaire score of the Japanese students (7.40) was significantly greater than that of the Greek peers (6.86, P = 0.001), indicating better oral self‐care behaviour amongst the Japanese students; however, the overall difference was mainly attributed to their additional sixth study year. Greek and Japanese students provided significantly different answers to 14 of 20 HU‐DBI items. Greeks significantly more often were required by their dentist to evaluate their brushing technique (OR = 14.4, P < 0.01), checked their teeth in the mirror after brushing (OR = 8.1, P < 0.01), worried about bad breath (OR = 6.7, P < 0.01), and believed that gum disease is preventable by tooth brushing alone (OR = 2.1, P < 0.05), whereas their Japanese peers significantly more often felt comfortable to clean their teeth without the use of a toothpaste (OR = 0.3, P < 0.01), believed that they take much time to brush their teeth (OR = 0.3, P < 0.01), used a child‐sized toothbrush (OR = 0.2, P < 0.01), and put off going to the dentist until having toothache (OR = 0.4, P < 0.01).

Conclusions:  Considerable differences in dental health attitudes/behaviour exist amongst students in the two countries reflecting the different culture and the health education system of the students; moreover, it is possible to distinguish Greek dental students from Japanese peers with a probability of more than 89% by using the HU‐DBI instrument.
Differential CD91 Dependence for Calreticulin and Pseudomonas Exotoxin‐A Endocytosis
Authors: Walters Julie Jo , Berwin Brent
Published: October 2005

Calreticulin (CRT) interaction with cell‐surface receptors is integral to its function in escorting associated peptides into the antigen‐presenting cell (APC) antigen presentation pathway. Additionally, extracellular CRT is proposed to be required for lung APC interaction with collectins. In both cases, CD91 has been proposed to act as the APC cell‐surface receptor requisite for mediating these processes. However, the evidence for a CRT interaction with CD91 is indirect, predicated on partial competition of cellular binding by gp96, of which CD91 has been proposed as the unique endocytic receptor, and by the CD91 ligand α2‐macroglobulin. Here, we directly investigate the function of CD91 in binding and trafficking CRT. We find that the ability of CRT to interact with APC does not correlate with cellular CD91 expression or function. Additionally, in the first genetic test of CD91 function regarding CRT, CD91 expression neither conferred CRT association nor did CD91‐deficient (CD91–/–) and CD91‐expressing cells differ in their ability to traffic CRT. Finally, cellular CRT trafficking did not parallel that of Pseudomonas exotoxin‐A, an obligate CD91 ligand, by the criteria of CD91 dependence, cell‐type specificity and endocytic itinerary. These data identify that CRT trafficking is not, as previously hypothesized, CD91 dependent and indicate usage of alternative cellular trafficking pathways.
Activation of the plasma membrane H+‐ATPase of Saccharomyces cerevisiae by glucose is mediated by dissociation of the H+‐ATPase–acetylated tubulin complex
Authors: Campetelli Alexis N. , Previtali Gabriela , Arce Carlos A. , Barra Héctor S. , Casale César H.
Published: October 2005

In the yeast Saccharomyces cerevisiae, plasma membrane H+‐ATPase is activated by d‐glucose. We found that in the absence of glucose, this enzyme forms a complex with acetylated tubulin. Acetylated tubulin usually displays hydrophilic properties, but behaves as a hydrophobic compound when complexed with H+‐ATPase, and therefore partitions into a detergent phase. When cells were treated with glucose, the H+‐ATPase–tubulin complex was disrupted, with two consequences, namely (a) the level of acetylated tubulin in the plasma membrane decreased as a function of glucose concentration and (b) the H+‐ATPase activity increased as a function of glucose concentration, as measured by both ATP‐hydrolyzing capacity and H+‐pumping activity. The addition of 2‐deoxy‐d‐glucose inhibited the above glucose‐induced phenomena, suggesting the involvement of glucose transporters. Whereas total tubulin is distributed uniformly throughout the cell, acetylated tubulin is concentrated near the plasma membrane. Results from immunoprecipitation experiments using anti‐(acetylated tubulin) and anti‐(H+‐ATPase) immunoglobulins indicated a physical interaction between H+‐ATPase and acetylated tubulin in the membranes of glucose‐starved cells. When cells were pretreated with 1 mm glucose, this interaction was disrupted. Double immunofluorescence, observed by confocal microscopy, indicated that H+‐ATPase and acetylated tubulin partially colocalize at the periphery of glucose‐starved cells, with predominance at the outer and inner sides of the membrane, respectively. Colocalization was not observed when cells were pretreated with 1 mm glucose, reinforcing the idea that glucose treatment produces dissociation of the H+‐ATPase–tubulin complex. Biochemical experiments using isolated membranes from yeast and purified tubulin from rat brain demonstrated inhibition of H+‐ATPase activity by acetylated tubulin and concomitant increase of the H+‐ATP ase–tubulin complex.
Psychological and Interpersonal Dimensions of Sexual Function and Dysfunction
Authors: Althof Stanley E. , Leiblum Sandra R. , Chevret-Measson Marie , Hartmann Uwe , Levine Stephen B. , McCabe Marita , Plaut Michael , Rodrigues Oswaldo , Wylie Kevan
Published: October 2005

Introduction

There are limited outcome data on the efficacy of psychological interventions for male and female sexual dysfunction and the role of innovative combined treatment paradigms.

Aim

To highlight the salient psychological and interpersonal issues contributing to sexual health and dysfunction; to offer a four-tiered paradigm for understanding the evolution and maintenance of sexual symptoms; and to offer recommendations for clinical management and research.

Methods

An International Consultation assembled over 200 multidisciplinary experts from 60 countries into 17 committees. The recommendations of committee members represent state-of-the-art knowledge and opinions of experts from five continents were developed in a process over a 2-year period. Concerning the Psychological and Interpersonal Committee of Sexual Function and Dysfunction, there were nine experts from five countries.

Main Outcome Measure

Expert opinion was based on grading of evidence-based medical literature, widespread internal committee discussion, public presentation, and debate.

Results

Medical and psychological therapies for sexual dysfunctions should address the intricate biopsychosocial influences of the patient, the partner, and the couple. The biopsychosocial model provides a compelling reason for skepticism that any single intervention (i.e., a phosphodiesterase type 5 inhibitor, supraphysiological doses of a hormone, processing of childhood victimization, marital therapy, pharmacotherapy of depression, etc.) will be sufficient for most patients or couples experiencing sexual dysfunction.

Conclusions

There is need for collaboration between healthcare practitioners from different disciplines in evaluation, treatment, and education issues surrounding sexual dysfunction. In many cases, neither psychotherapy alone nor medical intervention alone is sufficient for the lasting resolution of sexual problems. Assessment of male, female, and couples’ sexual dysfunction should ideally include inquiry about: predisposing, precipitating, maintaining, and contextual factors. Treatment of lifelong and/or chronic dysfunction will be different from acquired or recent dysfunction. Research is needed to identify efficacious combined and/or integrated treatments for sexual dysfunction.
Heart failure from diastolic dysfunction related to hypertension: Guidelines for management
Authors: Thomas‐Kvidera DeAnn
Published: October 2005

Purpose

To provide advanced practice nurses with a greater understanding of the pathophysiology, diagnostics, and management of diastolic dysfunction resulting from hypertension.

Data sources

Electronic database searches were performed using Medline and CINAHL. Data were obtained from medical textbooks and research and review articles.

Conclusions

As the number of older adults with heart failure (HF) continues to increase, so will the need for effective care and guidance. In addition to further testing of appropriate pharmacologic regimens, adherence factors such as medication costs and patients’ functional abilities must be considered.

Implications for practice

HF resulting from diastolic dysfunction has emerged as a separate entity over the past 10–15 years. One of the most common causes of diastolic dysfunction is uncontrolled hypertension. Populations at greatest risk include elders, particularly women, and African Americans.
Elastohydrodynamic Lubrication Modeling of Artificial Hip Joints Under Steady-State Conditions
Authors: Wang F. C. , Jin Z. M.
Published: September 2005

A general steady-state elastohydrodynamic lubrication model was developed for artificial hip joints, with particular reference to the effect of the anatomical position of the cup and the three-dimensional physiological loading and motion experienced during walking. Appropriate spherical coordinates and mesh grids were employed to facilitate the numerical solution. A specific hip implant employing an ultrahigh molecular-weight polyethylene acetabular cup against a metallic femoral head was chosen to demonstrate the general applicability of the lubrication model and the effects of both the cup inclination angle and the combined flexion-extension and internal-external rotation on the lubrication were analyzed.
Transient Three-Dimensional Solution for Thermoelastic Displacement Due to Surface Heating and Convective Cooling
Authors: Martini Ashlie , Liu Shuangbiao , Wang Q. Jane
Published: September 2005

In tribological contact, frictional heating may lead to temperature rise, which in turn may result in thermal displacement of the contacting bodies. The quantification of these effects is desirable in order to more accurately predict wear and failure of contacting surfaces. The change in temperature at a contact area may be attributed to the combined effects of frictional heating and convective cooling. This paper presents a transient, three-dimensional solution for the normal surface displacement of an elastic half-space due to an arbitrarily distributed, moving heat source and surface convection.
Friction Control of Active-Head Slider During Flying Height Adjustment
Authors: Su Lizhi , Xu Junguo , Kurita Masayuki , Kato Koji , Adachi Koshi , Miyake Yoshihiko
Published: September 2005

To reduce the risk of head crash when a slider contacts a smooth disk during flying height adjustment, a novel tapping method for reducing the friction and lowering the risk of head crash was developed. An active-head slider was designed and fabricated to demonstrate the usefulness of the tapping approach. It is also found that micro-vibration is significantly effective in avoiding a high friction force and protecting a head from the crash due to head-disk contact during the flying height adjustment.
The Quantification of Physiologically Relevant Cross-Shear Wear Phenomena on Orthopaedic Bearing Materials Using the MAX-Shear Wear Testing System
Authors: Gevaert Matthew R. , LaBerge Martine , Gordon Jennifer M. , DesJardins John D.
Published: September 2005

Background: The occurrence of multi-directional sliding motion between total knee replacement bearing surfaces is theorized to be a primary wear and failure mechanism of ultra-high molecular weight poly(ethylene) (UHMWPE). To better quantify the tribologic mechanisms of this cross-shear wear, the MAX-Shear wear-testing system was developed to evaluate candidate biomaterials under controlled conditions of cross-shear wear. Method of approach: A computer controlled traveling x-y stage under a 3 degree-of-freedom statically loaded pin is used to implement the complex multi-directional motion pathways observed during TKR wear simulation. A MHz collection of dynamic x-y friction was available on all six environmentally controlled stations. The functionality of this testing platform was proven in a 100,000 cycle, 11.6 MPa, wear test using 15.0 mm diameter polished stainless steel spheres against flat GUR4150 UHMWPE. A five-pointed star wear pattern was used to incorporate the physiologically relevant cross-shear sliding conditions of stop/start, 50mm∕s entraining velocity and five crossing angles of 72°. Using normalized volumetric reconstruction of the resulting surface damage, a direct quantitative relationship between linear and cross-shear surface damage intensity was obtained. Results: Cross-shear surface damage volume loss was found to be 2.94 (±0.88) times that associated with linear sliding under identical tribologic conditions. SEM analysis of linear wear damage showed consistent fibril orientation along the direction of sliding while cross-shear wear damage showed multi-directional fibril orientations and increased surface roughness. Significant increases in discrete crossing-point friction coefficients were recorded throughout testing. Conclusions: This scientific approach to quantifying the tribologic effects of cross-shear provides fundamental wear mechanism data that are critical in evaluating potential biomaterials for use as in vivo bearings. Relevant multi-axis, cross-shear wear testing is necessary to provide quantifiable measures of complex biomaterials wear phenomena.
Virtual Texturing: Modeling the Performance of Lubricated Contacts of Engineered Surfaces
Authors: Wang Q. Jane , Zhu Dong
Published: September 2005

Engineering practices and analyses have indicated that surface textures and topography may significantly affect the tribological performance of contact interfaces. Such an influence may be complicated and difficult to be captured with only a few statistic surface parameters. The need for further improvement of the performance and life of machine elements requires that surface topography and textures be optimized. The utilization of a numerical tool to determine the basic geometric aspects of surface textures may be named a virtual texturing technology, with which surface optimization may start from patterned surfaces where topography can be precisely quantified and the relationship between textures and lubrication performance can be numerically established. Presented in this paper are the concept of the virtual texturing technology, models involved, and a preliminary exploration of the relationship between a dimpled texture design and the mixed lubrication characteristics for a typical counterformal contact. The dimple influence area and the number of interruption are found to be two key factors for designing dimpled surfaces for counterformal contact lubrication. It is demonstrated that virtual texturing is able to provide comparative information and directions for innovative surface design and optimization.
Statistical Distribution of Tapered Roller Bearing Fatigue Lives at High Levels of Reliability
Authors: Kotzalas Michael N.
Published: September 2005

The original two-parameter Weibull distribution used for rolling element fatigue tends to under-estimate life at high levels of reliability. This is due to the fact that a finite life value for which 100% of the population will survive cannot be considered with this method. However, empirical evidence of a minimum life at 100% reliability has been shown for through hardened ball and spherical roller bearings, linear ball bearings, and tapered roller bearings (TRB), however, for TRB’s there is no mention as to the heat treatment nor is there a method put forth to approximate the data. Therefore, an experimental data set of 9702 TRB’s, 98% case carburized (CC), and another data set of 280 through hardened (TH) TRB’s were collected and utilized to provide evidence of a finite life at 100% reliability. The current data for both heat treatments appeared to follow that previously published for TRB’s, however, varied from published work on other bearing types. Next, a three-parameter Weibull distribution was fit to the CC data and found to be equally applicable to the TH data set. Use of this three-parameter Weibull distribution reduced the overall root-mean square (RMS) error over both data sets by at least half, and at very high reliability levels by at least one-third compared to the two-parameter Weibull, both conservatively underestimating. However, as there is still some error in the three-parameter Weibull fit and differences in the results based upon bearing type and date of study, more investigation should be conducted in this area to identify the proper variables and the true statistical distribution for all rolling bearing constructions.
A Compact Model for Spherical Rough Contacts
Authors: Bahrami M. , Yovanovich M. M. , Culham J. R.
Published: September 2005

A new model is developed that considers the effect of roughness on the elastic contact of spherical bodies. A general pressure distribution is proposed that encompasses the contact of rough spheres and yields the Hertzian theory for ideally smooth surfaces. A new parameter, nondimensional maximum contact pressure, is introduced and it is shown that this is the key parameter that controls the contact. The results of the present study are presented in the form of compact relationships. These relationships are compared against the experimental data collected by others and good agreement is observed.
Thermal Analysis of the Transient Temperatures Arising at the Contact Spots of Two Sliding Surfaces
Authors: Lin Jen Fin , Chung Jung Ching , Chen Jeng Wei , Liu Ta Chuan
Published: September 2005

The three-dimensional hyperbolic heat conduction equation is solved to obtain the analytical solution of the temperature rise at the contact area between an asperity and a moving smooth flat. The present analyses can provide an efficient method to avoid the problem of being difficult to give the correct boundary conditions for the frictional heat conduction at an asperity. The mean contact area of an asperity which is needed in the heat transfer analysis is here obtained by a new fractal model. This fractal model is established from the findings of the size distribution functions developed for surface asperities operating at the elastic, elastoplastic and fully plastic regimes. The expression of the temperature rise parameter T∕f (T: Temperature rise, f: friction coefficient) is thus derived without specifying the deformation style of a contact load. It can be applied to predict the T∕f variations due to the continuous generations of the frictional heat flow rate in a period of time. The combination of a small fractal dimension and a large topothesy of a surface is apt to raise the contact load, and thus resulting in a large T∕f value. A significant difference in the behavior exhibited in the parameters of temperature rise and temperature rise gradient is present between the Fourier and hyperbolic heat conductions; Fluctuations in the thermal parameters are exhibited only when the specimen material has a large value of the relaxation time parameter.
Grain Flow for Rough Surfaces Considering Grain/Grain Collision Elasticity
Authors: Jeng Yeau-Ren , Tsai Hung-Jung
Published: September 2005

Previous work by this group on an average lubrication equation for grain flow with roughness effects is extended to include grain-grain collision elasticity ranging from perfectly elastic to perfectly inelastic. The average lubrication equation is based on Haff’s grain flow theory, with flow factors from Patir and Cheng and Tripp’s use of perturbation. The derived flow factors are obtained as functions of rough surface characteristics, grain size, and collision pattern. As collision energy loss approaches zero, the inelastic results approach those for perfectly elastic grain collision. The mathematical formulas for flow factors, grain/grain collision elasticity, grain size, and roughness are presented and discussed. Predicitons for the elastic and inelastic cases are graphically demonstrated and compared. The derived average lubrication equation for grain flow shows good agreement with the theoretical and experimental data of Yu, Craig, and Tichy [J. Rheol., 38(4), 921 (1994)].
CFD Analysis of a Low Friction Pocketed Pad Bearing
Authors: Brajdic-Mitidieri P. , Gosman A. D. , Ioannides E. , Spikes H. A.
Published: September 2005

A CFD method has been applied to model lubricant flow behavior within linear pad bearings having large, closed pockets or recesses. The study shows that the presence of closed pockets can result in a significant reduction in bearing friction coefficient and that there are two different origins for this, depending on the bearing convergence ratio. At high convergence ratios, as used in conventional thrust bearings, a pocket located in the high-pressure region of the bearing produces a reduction in local shear stress and thus friction. This friction reduction is larger than the reduction in load support resulting from the presence of the pocket so there is a net overall reduction in friction coefficient. In low convergence ratio bearings, each pocket also acts as an effectively-independent step bearing and thereby generates a higher local pressure than would otherwise be the case. This results in the overall bearing having enhanced load support and thus a reduced friction coefficient. This effect is particularly large at very low convergence ratios when cavitation occurs in the pocket inlet.
Influence of Contact Pressure on Central and Minimum Film Thickness Within Ultrathin Film Lubricated Contacts
Authors: Křupka I. , Hartl M. , Liška M.
Published: September 2005

Recent numerical results have indicated that the relationship between the film thickness and the speed may not always follow the simple power law, especially under severe conditions. This paper is aimed at obtaining experimental results at high contact stresses and low speeds to study the thin film behavior. Ultrathin lubricant films were observed at maximum Hertz pressures of 0.52, 1.01, and 1.54 GPa by using an optical test rig. Central and minimum film thickness values were obtained with thin film colorimetric interferometry from chromatic interferograms. The nonlinear behavior of both central and minimum film thicknesses in log-log coordinates was observed as rolling speed and thereby film thickness decreased. This tendency became more obvious at higher contact pressures.
Modified Reynolds Equation for Non-Newtonian Fluid With Rheological Model in Frequency Domain
Authors: Haosheng Chen , Darong Chen
Published: September 2005

The purpose of this paper is to provide a lubrication equation for non-Newtonian fluid. Three nonlinear functions instead of common power law model are used to describe non-Newtonian properties more completely. They are shear dependent viscosity, first normal stress difference and stress relaxation. After the coordinate conversion which is needed for the lubricant film thickness variation, the functions are involved in the modified Reynolds equation and show their effects on the lubrication results. As the principle factor in lubrication, viscosity is expressed by a first order transfer function in frequency domain. Its variation process is described by the function’s amplitude frequency response curve, which is validated by rheological experiment. Numerical results of the modified Reynolds equation show that non-Newtonian lubricant’s load capacity is not always higher or lower than Newtonian lubricant’s, and non-Newtonian lubricant has flatter pressure profile at high working speed.