When are actively balanced biphasic (‘Lilly’) stimulating pulses necessary in a neurological prosthesis? I Historical background; Pt resting potential;Q studies

Actively balanced (‘Lilly’) stimulating current waveforms are generally considered to give very ‘safe’ stimulation. Although this is perfectly true, the specification of the necessary waveform generators in neurological prostheses demands additional complexity, and probably additional expense and development time as well. The paper and its companion enquire whether the use of simple, passively charge-balanced stimulating pulses is equally safe, provided the stimulation parameters and circuitry are designed with appropriate care. It is concluded that, in respect of safe deliverable charge density per pulse at the electrode, release of noxious products and stimulating effectiveness, simple pulses need give no worse performance; in some circumstances they may give better.     

When are actively balanced biphasic (‘Lilly’) stimulating pulses necessary in a neurological prosthesis? II pH changes; noxious products; electrode corrosion; discussion

Actively balanced (‘Lilly’) stimulating current waveforms are generally considered to give very ‘safe’ stimulation. Although this is perfectly true, the specification of the necessary waveform generators in neurological prostheses demands additional complexity, and probably additional expense and development time as well. The paper and its companion enquire whether the use of simple, passively charged-balanced stimulating pulses is equally safe, provided the stimulation parameters and circuitry are designed with appropriate care. It is concluded that, in respect of safe deliverable charge density per pulse at the electrode, release of noxious products and stimulating effectiveness, simple pulses need give no worse performance; in some circumstances they may give better.     

Computerised acoustical respiratory phase detection without airflow measurement

A simple, non-invasive acoustical method is developed to detect respiratory phases in relationship to swallows without the direct measurement of airflow. In 21 healthy subjects (4–51 years) breath sounds are recorded at the trachea and at five different recording locations at the chest wall, with simultaneous recording of airflow by a pneumotachograph. The chest signal with the grestest inspiratoryexpiratory power difference (‘best location’) is either in the mid-clavicular line in the second interspace on the left or third interspace on the right. Using the ‘best developed and achieves 100% accuracy in the estimation of respiratory phases without using the measured airflow signal. Thus, acoustically monitoring breaths and swallows holds promise as a non-invasive and reliable assessment tool in the study of swallowing dysfunction.     

Non-constraining sleep/wake monitoring system using bed actigraphy

This paper introduces a new method, bed actigraphy (BACT) for user-friendly sleep-wake monitoring. BACT provides a non-intrusive acquisition of activity data, and in particular does not require that sensors be attached to the subject’s body. The system consists of four load-sensing cells supporting the bed, an A/D converter, and a microcontroller with appropriate software. The performance of BACT was compared to that of standard polysomnography (PSG) recordings and wrist-worn actigraphy (ACT). Ten normal volunteers underwent overnight PSG recordings and were examined simultaneously with BACT and ACT. An automatic scoring algorithm scored each 30-s epoch of the BACT recordings for either ‘Wake’ or ‘Sleep.’ A sleep specialist manually scored the PSG recordings, and the results were divided into ‘Wake’ and ‘Sleep’ categories. The three methods showed a significant correlation when compared with in the contingency test. The mean epoch-by-epoch agreements between the BACT and PSG, ACT and PSG, and BACT and ACT recordings were 95.2, 92.9, and 94.3%, respectively. The mean absolute differences in sleep percentage (SP) between them were 1.8 ± 0.82, 3.4 ± 1.45, and 1.9 ± 1.16 %, respectively. BACT differentiation of the ‘Wake’ and ‘Sleep’ stages proved to be sufficiently robust, and its results were comparable to PSG analysis. This finding supports the experimental and clinical value of bed-activity monitoring during sleep.     

Fractal dynamics of polarized bioelectrodes

This study is concerned with mathematical modelling of the fundamental relationship which exists between the current density and the overpotential across the metalsolution interface in the linear range using methods of system theory enhanced by ‘fractal’ concepts. A primer for both 1/f-type scaling and ‘anomalous’ relaxation/dispersion concepts is provided, followed by a brief review of the research history pertinent to the metal electrode polarization dynamics. Next, the ‘fractal relaxation systems’ approach is introduced to characterize, systems which attenuate with a fractional power-low dependence on frequency through a ‘scaling exponent’. The ‘singularity structure’ which is a scaling, rational system function is proposed to expand fractal systems in terms of basic subsystems individually representing elementary exponential relaxations and collectively exhibiting scaling properties. We stress that the ‘singularity structure’ carries scaling information identical to the conventional ‘distribution of relaxation times’ function. ‘Structure scale’ and ‘view scale’ concepts are presented in the due course to streamline the analysis of scaling phenomena in general and the polarization impedance in particular. System theory-wise, the notable result is that the fractional power function attenuation, or equivalently, the logarithmic nature of the distribution function translates into the ‘self-similar’ pattern replication of the system singularities in the s-plane. The singularity arrangement is governed by a recursive rule solely based on the knowledge of the fractional power factor or the scaling exponent.     

Distractor objects affect fingers’ angular distances but not fingers’ shaping during grasping

The aim of the present study was to determine whether and how hand shaping was affected by the presence of a distractor object adjacent to the to-be-grasped object. Twenty subjects were requested to reach towards and grasp a ‘convex’ or a ‘concave’ object in the presence or absence of a distractor object either of the same or different shape than the target object. Flexion/extension at the metacarpal-phalangeal (MCP) and proximal interphalangeal joints of all digits, and abduction angle between digits were measured by resistive sensors embedded in a glove. The results indicate robust interference effects at the level of reach duration and the extent of fingers’ abduction angles together with changes at the level of a single joint for the thumb. No distractor effects on individual fingers’ joints except for the MCP of the middle and little fingers were found. These findings suggest that the presence of distractor object affects hand shaping in terms of fingers’ abduction angles, but not at the level of ‘shape dependent’ fingers’ angular excursions. Furthermore, they support the importance of the thumb for the guidance of selective reach-to-grasp movements. We discuss these results in the context of current theories proposed to explain the object selection processes underlying the control of hand action.     

Automatic detection of the electrocardiogram T-wave end

Various methods for automatic electrocardiogram T-wave detection and Q-T interval assessment have been developed. Most of them use threshold level corrsing. Comparisons with observer detection were performed due to the lack of objective measurement methods. This study followed the same approach. Observer assessments were performed on 43 various T-wave shapes recorded: (i) with 100 mms⁻¹ equivalent paper speed and 0.5mVcm⁻¹ sensitivity; and (ii) with 160 mms⁻¹ paper speed and vertical scaling ranging from 0.07 to 0.02 m Vcm⁻¹, depending on the T-wave amplitude. An automatic detection algorithm was developed by adequate selection of the T-end search interval, improved T-wave peak detection and computation of the angle between two 10ms long adjacent segments along the search interval. The algorithm avoids the use of baseline crossin direct signal differentiation. It performs well in cases of biphasic and/or complex T-wave shapes. Mean differences with respect to observer data are 13.5 ms for the higher gain/speed records and 14.7 ms for the lower gain/speed records. The algorithm was tested with 254 various T-wave shapes. Comparisons with two other algorithms are presented. The lack of a ‘gold standard’ for the T-end detection, especially if small waves occur around it, impeded adequate interobserver assessment and evaluation of automatic methods. It is speculated that a simultaneous presentation of normal and high-gain records might turn more attention to this problem. Automatic detection methods are in fact faced with ‘high-gain’ data, as high-resolution analogue-to-digital conversion, is already widely used.     

Classification of resistance to passive motion using minimum probability of error criterion

Neurologists diagnose many muscular and nerve disorders by classifying the resistance to passive motion of patients' limbs. Over the past several years, a computer-based instrument has been developed for automated measurement and parameterization of this resistance. In the device, a voluntarily relaxed lower extremity is moved at constant velocity by a motorized driver. The torque exerted on the extremity by the machine is sampled, along with the angle of the extremity. In this paper a computerized technique is described for classifying a patient's condition as ‘Normal’ or ‘Parkinson disease’ (rigidity), from the torque versus angle curve for the knee joint. A Legendre polynomial, fit to the curve, is used to calculate a set of eight normally distributed features of the curve. The minimum probability of error approach is used to classify the curve as being from a normal or Parkinson disease patient. Data collected from 44 different subjects was processed and the results were compared with an independent physician's subjective assessment of rigidity. There is agreement in better than 95% of the cases, when all of the features are used.     

Antenatal psychosocial assessment: how accurate are we in determining ‘low-risk’ status? A pilot study

Routine Comprehensive Psychosocial Assessment was implemented antenatally at a public hospital in Sydney in 2000. The assessment, completed on all women, classifies them as (1) currently, or at high-risk of becoming, distressed, or, (2) not currently, or at low risk of becoming, distressed during the perinatal period. This pilot study followed up a sample of women (N = 50) from the latter group at 6 weeks postpartum to explore the accuracy of ‘low risk’ identification. All but one woman reported that they continued to do well during their pregnancy. By 6 weeks postpartum only one woman scored high on the validated depression measure though data from a semi-structured interview indicated that a further four women experienced sub-clinical difficulty in the early weeks postpartum. The antenatal classification of women as ‘low risk’ using this assessment method appears to be substantially accurate, though this finding needs to be replicated in a larger study.     

Aortic rhythmic wrinkling in youth: the PDAY study

Transverse, white-streak ‘wrinkles’ in the aorta were first described as Querlinien (cross lines) or Wellenlinien (wave lines) in the German literature in the early 20th century. These rhythmic structures were previously thought to be artifacts of stretching and shrinkage of the aorta. Not until the 1970s was it proposed that the areas of rhythmic wrinkling (RW) might be part of the process of atherosclerosis. We analyzed 2,650 aortas from the Pathobiological Determinants of Atherosclerosis in Youth (PDAY) study for prevalence, extent, and topographical distribution of these areas of RW. Furthermore, we investigated the possible relationship of RW to atherosclerotic sudanophilic stained ‘fatty streaks’ and elevated intimal lesions called ‘raised lesions’ (RL). This study provides evidence that (1) the prevalence of RW is fairly high in the aorta and occurs in a specific distribution in both the thoracic and abdominal aorta; (2) RW seems to precede the development of RL, with RL occurring in the same topographical areas as RW; and (3) RW may be associated with the subsequent development of advanced atherosclerosis, particularly raised lesions.     

Sequence diversity of NS(M) movement protein of tospoviruses

Summary.  In order to determine the diversity of the movement protein (NS_M) among tospoviruses, the NS_M genes of five distinct tospovirus species occurring in Brazil (Tomato chlorotic spot virus, Groundnut ring spot virus, Chrysanthemum stem necrosis virus, Zucchini lethal chlorosis virus and Iris yellow spot virus) were cloned, sequenced and compared with NS_M sequences of other available tospoviruses. The ‘D-motif’, a conserved region present in the majority of ‘30K superfamily’ virus movement proteins, is present in all NS_M amino acid sequences available. In addition to the ‘D-motif’, a conserved phospholipase A2 motif was found. The NS_M amino acid sequence comparisons among tospovirus species revealed several conserved regions located in the internal part of the protein and diverse domains mainly located in the amino-terminus. Prediction of secondary structure showed similar patterns among all NS_M proteins analyzed. Considering the geographical prevalence and phylogenetic analysis of N and NS_M proteins, tospoviruses were tentatively clustered in ‘American’ and ‘Eurasian’ groups. Both phylogenetic trees may reflect the natural evolution of tospovirus species within distinct ecological niches. The sequence information obtained in this work would facilitate functional analysis of NS_M during the tospovirus infection process. Received July 18, 2000 Accepted February 28, 2001     

经肛吻合器直肠切除术治疗女性出口梗阻型便秘临床效果观察

目的:探讨经肛吻合器直肠切除术（STARR）治疗以直肠前突（或合并直肠黏膜内脱垂）为主的女性出口梗阻型便秘的临床疗效。方法:简介手术所用的肛肠吻合器。对58例以直肠前突（或合并直肠粘膜内脱垂）为主要病因的女性出口梗阻型便秘患者实施STARR手术前后的主观感受、便秘评分、排粪造影进行分析比较。结果:术后所有病人主观感觉排便困难症状缓解,排便较术前畅通;术后1周、1月、3月与术前便秘评分比较差异有统计学意义（P<0.05）;术后1、3月排粪造影结果提示直肠前突、直肠黏膜内脱垂较术前明显好转（P<0.01）。结论:STARR手术是治疗以直肠前突（或合并直肠粘膜内脱垂）为主因的女性出口梗阻型便秘的一个安全有效的手术方式,但应严格掌握其适应证。     

Reasons women give for abortion: a review of the literature

The aim was to identify from empirical research that used quantitative or qualitative methods the reasons women give for having an abortion. A search was conducted of peer-reviewed, English language publications indexed in eight computerized databases with publication date 1996–2008, using keywords ‘abortion’ and ‘reason’ (Medline: ‘induced abortion’ OR ‘termination of pregnancy’ OR ‘elective abortion’ and ‘reason’). Inclusion criteria were empirical research on humans that identified women’s reasons for undergoing an abortion, conducted in ‘high-income’ countries. 19 eligible papers were found. Despite variation in methods of generating, collecting, and analysing reasons, and the inadequacy of methodological detail in some papers, all contributed to a consistent picture of the reasons women give for having an abortion, with three main categories (‘Woman-focused’, ‘Other-focused’, and ‘Material’) identified. Ambivalence was often evident in women’s awareness of reasons for continuing the pregnancy, but abortion was chosen because continuing with the pregnancy was assessed as having adverse effects on the life of the woman and significant others. Women’s reasons were complex and contingent, taking into account their own needs, a sense of responsibility to existing children and the potential child, and the contribution of significant others, including the genetic father.     

Influence of diet on metastasis and tumor dormancy

Tumor metastasis is responsible for most cancer deaths, and can occur after long periods of tumor dormancy. Information learned from experimental studies on tumor metastasis and dormancy is shedding light on mechanisms responsible and possible therapeutic approaches. ‘Seed’ (the cancer cell) and ‘soil’ (the microenvironment of the secondary organ) factors contribute to metastatic outcome. This review considers the possibility that various dietary components may affect both ‘seed’ and ‘soil’ compartments, thereby influencing the growth of metastases, and discusses an experimental study on dietary genistein that illustrates this concept. While studies on human diet are complex, the possibility that relatively non-toxic dietary intervention strategies could impact on metastasis and patient survival is attractive and worthy of further study in appropriate experimental models of metastasis and tumor dormancy.     

Mindful pregnancy and childbirth: effects of a mindfulness-based intervention on women’s psychological distress and well-being in the perinatal period

This pilot study explored the effects of an 8-week mindfulness-based cognitive therapy group on pregnant women. Participants reported a decline in measures of depression, stress and anxiety; with these improvements continuing into the postnatal period. Increases in mindfulness and self-compassion scores were also observed over time. Themes identified from interviews describing the experience of participants were: ‘stop and think’, ‘prior experience or expectations’, ‘embracing the present’, ‘acceptance’ and ‘shared experience’. Childbirth preparation classes might benefit from incorporating training in mindfulness.     

Finger interaction during maximal radial and ulnar deviation efforts: experimental data and linear neural network modeling

The purpose of this study was to characterize finger interactions during radial/ulnar deviation, including interactions with flexion movements. Subjects performed single-finger and multi-finger maximal voluntary contraction (MVC), and maximal forces and various indices of interaction among the fingers were quantified. MVCs in radial/ulnar deviation were 50–80% as strong as in flexion. Along with the ‘master’ fingers (i.e., those explicitly instructed to produce force), substantial force production was also observed in ‘slave’ fingers (i.e., those not explicitly instructed to produce force), a phenomenon termed: force ‘enslaving’. In addition, a drop in MVC during multi-finger tasks as compared to single finger tasks (force ‘deficit’) was also observed. A previously unreported phenomenon that we term: ‘preferred direction enslaving’ was also apparent; both master and slave fingers produced force in the instructed direction with a non-zero perpendicular component. Due to the architectural separation of the involved muscles, preferred direction enslaving provides strong evidence that enslaving results from neural rather than biomechanical factors. A final new phenomenon: ‘negative deficit’, or force ‘facilitation’ was observed in 46.4% of the trials in 21 out of 23 subjects during multi-finger lateral efforts and was further demonstrative of extensive interconnection among neurons serving hand muscles. The data were modeled with high accuracy (∼4% mean square error) using a linear neural network with motor ‘commands’ as inputs and finger forces as outputs. The proposed network, equivalent to linear regression, can be used to determine the extent to which finger forces are influenced by peripheral constraints during functional prehensile activities.     

Age Differences in Genetic and Environmental Variations in Stress-Coping During Adulthood: A Study of Female Twins

The way people cope with stressors of day to day living has an important influence on health. The aim of the present study was to explore whether genetic and environmental variations in stress-coping differ over time during adulthood. The brief COPE was mailed to a large sample of the UK female twins (N = 4,736) having a wide range of age (20–87 years). Factor analyses of the items of the brief COPE yielded three coping scales: ‘Problem-Solving’, ‘Support Seeking’, and ‘Avoidance’. Monozygotic and dizygotic twin correlations tended to become lower with age for all three scales, suggesting that unique environmental factors may become more important with age during adulthood. Model-fitting results showed that relative influences of unique environmental factors increased from 60 % at age 20 years to 74% at age 87 years for ‘Problem-Solving’ and 56 % at age 20 years to 76% at age 87 years for ‘Avoidance’. During the same age period, genetic factors decreased from 40 to 26 % for ‘Problem-Solving’ and from 44 to 24 % for ‘Avoidance’. For ‘Seeking Support’, the magnitude of genetic and unique environmental factors was not significantly different across the adulthood. For all three scales, shared environmental effects were negligible. Overall, our findings implicate that the effects of environment that stem from idiosyncratic experience of stressful life events accumulate and become increasingly important in adulthood.     

Pre-screening via sleep logs in sleep-disordered patients—Adaptational effects, yes or no?

Summary Question of the study  Sleep logs are common tools in sleep research and clinical routine. Usually sleep logs have to be completed during a 2-week period, with the first week serving as an adaptation to the instrument itself. In the present study, we investigated whether there is indeed such an adaptation bias or not. Patients and methods  A total of 236 chronically sleep-disordered outpatients completed the standardized sleep log ‘Abend-Morgen-Protokoll’ during a 2-week pre-screening period prior to the first visit in our sleep ambulance. Two sets of items were established, the ‘instrumental’ and the ‘therapeutic’ set. The respective ratings of the first and second week (week A, B) were compared to evaluate clinically relevant changes. Results  The ratings of several ‘instrumental’ items significantly differed between week A and B. However, these changes—on average—were only marginal and therefore of little clinical importance. Regarding the ‘therapeutic’ set of items, no systematic variations could be ascertained over the assessment period. Conclusion  The present investigation could not confirm the presence of adaptation biases (instrumental, therapeutic) in a large sample of chronically sleep-disordered outpatients. Therefore, we consider a 1-week pre-screening period via sleep log as sufficient for the diagnostic process in these patients.      

Phase response curve based model of the SA node: simulation by two-dimensional array of pacemaker cells with randomly distributed cycle lengths

A simulation of the SA node is presented, based on a 2D array (15×15) model of randomly distributed pacemaker cells, interacting via a phase response curve (PRC). The model involves only the basic properties that play a direct role in the determination of the SA node rhythm: intrinsic cycle length and PRC. The PRC reflects the ‘type’ of interaction of each pacemaker cell with the outside world (neighbouring cells, external stimulus, etc.). A major outcome of this study is the demonstration that global dynamics and the degree of ‘disorder’ of the SA node are strongly affected by the cycle length distribution of the model, as well as spatial inhomogeneity in the cell-to-cell ‘electrical’ coupling (PRC). Those factors also determine the conduction velocity throughout the SA node and may therefore be responsible for anisotropic conduction. For example, lowering the PRC parameters (d and a) by 25% increases the array activation time from 46 to 126 ms. The model also responds appropriately to a perturbation such as a vagal pulse. This pulse produces a shift of the dominant pacemaker to another site in the array and a transient lengthening of the array cycle length, for example from 312 to 355 ms.     

Auditory temporal modulation of the visual Ternus effect: the influence of time interval

Research on multisensory interactions has shown that the perceived timing of a visual event can be captured by a temporally proximal sound. This effect has been termed ‘temporal ventriloquism effect.’ Using the Ternus display, we systematically investigated how auditory configurations modulate the visual apparent-motion percepts. The Ternus display involves a multielement stimulus that can induce either of two different percepts of apparent motion: ‘element motion’ or ‘group motion’. We found that two sounds presented in temporal proximity to, or synchronously with, the two visual frames, respectively, can shift the transitional threshold for visual apparent motion (Experiments 1 and 3). However, such effects were not evident with single-sound configurations (Experiment 2). A further experiment (Experiment 4) provided evidence that time interval information is an important factor for crossmodal interaction of audiovisual Ternus effect. The auditory interval was perceived as longer than the same physical visual interval in the sub-second range. Furthermore, the perceived audiovisual interval could be predicted by optimal integration of the visual and auditory intervals.